i've been in the hvac business for 19 years, but mostly residential and light commercial. i've never really understood unloaders until i watched your video. thanks so much for sharing this
I'm so glad that my video helped you understand unloaders! Thank you so much for your kind words and I am so glad I could help! Thank you and keep learning out there!
Soil heavsystom gas potavting systom soild conrold mechionom sely gas insidd pards dsmgd sdlfeyunlored opn coglod moregax powed edom potacting inside parts slftg valplat hedpate pidon all poractinv sydtim rightedunlored pudhinschion t go oponvslvd op pas dis tbuitng systo motr aut msticsl off self gax lord inde nog pas sinv hevey equpited ok
Wow! Thank you so much for your kind words! I love teaching, and it gets me motivated even more when I know I'm helping you guys out there! Thank you for watching!
Thank you so much! I really appreciate comments like this! It took me a while to make this video because I do all of this myself. I'm glad I could help! Good luck out there! And keep learning!
Thank you! I'm so glad to hear that. That's why I make these videos, I want to help you guys out there! I'm glad you liked the video and thank you for watching!
I'm glad you like the video and I am glad that it made sense to you! Keep watching the videos and maybe the other ones will help some more! Good luck out there!
I am not sure without actually looking at it, but it sounds like it may still be part of an unloader. There are so many different configurations out there with a short description it is hard to tell. I'm sorry
Am Godfrey Ssemagobwe from Uganda, sir I really appreciate the much effort you put in teach us more about refrigeration and air-condition, if all goes well I will be attending online course from your Academy. It is really interesting sir.
Thank you so much!!!! The TXV is controlling the refrigerant going in to the evaporator, this is controlling the refrigerant going in to the compressor so you can adjust the capacity of the unit or the compressor. so you can turn the unit in to a 10 ton in stead of a 15 ton and back in to a 15 in case you need more cooling. I hope this answers your question? and Thank you so much for the kind words. thank you for watching.
@AirConAcademy we can control the cooling by txv adjustment if it's electronically controlled txv based on temp, so by unloading the compressor also we're reducing the cooling performance, right? Only difference is if we reduce compressor load , energy is saved extra , right????
@@bt9604 by adjusting the TXV, even if you are using an electronically controlled TXV, you are only adjusting the super heat in the evaporator. You are not adjusting the room temperature. A lot of times when you have an electronic expansion valve. The compressor is going to be an inverter unit, meaning that as the electronic expansion valve adjust or let's say closes the comp is going to slow down also. So it is not just a matter of adjusting the expansion valve. We have to worry about what the compressor is doing also. The unloader is actually going to adjust capacity of the compressor to meet the load demand. So it will turn a 30 ton compressor into only a 20 ton compressor, or maybe even a compressor depending on the application. if you do not adjust the speed of the compressor and you close the TX some your evaporator temperature will drop and it could freeze the coil because compressor speed was not adjusted. Hopefully this explains your question?
What a fantastic explanation. You are a great teacher and definitely it comes through a lot of experience and high educational background. Thank you for sharing. I liked your video.
Good explanation. I used to work with these compressors, Carrier model O5G 6 cylinders in motor coaches. They were belt driven by the bus engine. When the unloader coil on a head. was electrically energized, those cylinders were unloaded. Lots of guys were confused by this. You could actually feel each side of the outer heads and sense a temperature difference from one side to the other. Low side, high side. I would watch the needles on the gauges "jump" when the unloader went from energized to densrgized.
Yes, you are correct. A lot of guys get confused with the loading and unloading and with the pressures rising and falling as it loads and unloads. I am glad he liked the video. Thank you for watching!
Could you please explain the oil flow in the compressor where there is oil pump to maintain oil pressure. What could be the differential oil pressure in the system and how it is maintained? Basically please try explain all the points related oil pressure and oil flow. Thanks alot.
Oil is pulled out of the oil sump at the bottom of the compressor, the oil pump that is at the front of the compressor will pump it through the crankshaft, because the crankshaft is hollow, the crankshaft has holes in it where the bearings are, so as the pump pulls the oil out of the oil sump it pumps it into the shaft and through the holes and it lubricates the bearings as it lubricates the oil falls back down to the oil sump to be used again. I hope this explains it. Thank you for watching!
I have watched a lot of technical teachers on compressors, on you tube. Some would talk and talk and include practical works and the more you try to learn from them, to mire confused you become. But in your case your explanation is very clear and easily understood. I'm a factory owner in west Africa. I handle heavy industrial and commercial equipments and have large stock from Copland, Carrier, Hitachi, Bitzer, Duareen etc. I build blasting units, cold storage facilities, as well as air Condition commercial and residential buildings. I would like to watch more of your videos, as well as share Ideas. Thanks.
Thank you so much for your kind words. I am so glad that I can help people understand how things work. please tell your friends and co workers about these videos and have them subscribe to my channel. If you have any suggestions for videos please send me a message. Thank you
Thank you so much for your kind words! I enjoyed teaching, so I am so glad that I could help! If you get a chance, check out my webpage airconacademy.com I know I did not like school because I did not have any teachers that could actually teach. I enjoyed teaching so I think that makes a difference. Thank you for watching!
Hey brother, I just worked on a bus with a '05G compressor. It runs on r134a There are two valves located on it. Do you know if they need to be turned all the way in for it to be open or do they need to be turned all the way out for it to be open? And also what should be the running pressure at 100° f? The charts do not make sense because I compare it with other r134a compressors on smaller vehicles and they are way different? The '05g compressor is running at 70 psi on the low suction side and 225 on the high side at 100° f
The two valves you are talking about are they suction service valve and the discharge service valve. Those valves need to be opened all the way to where it is called back seated. When they are all the way to the back, you will not have access, or you will not be able to read precious when you hook up gauges. If you want to pressures at the compressor then, they should be with the mid position or cracked. That means that they are off of the backseat. If you close the valves completely, then they are considered front seated, and the compressor will not run because there will be no flow of refrigerant through it. Those pressures are giving me seem to be pretty close. Do you have a site glass anywhere on the liquid line or on the receiver/dryer? Do you want to make sure you have enough subcooling and with the bus running a different speed your pressures are going to change. As the bus speeds up the engine wraps up, which is going to turn that compressor faster and change your pressures. So you need to make sure you have sub cooling coming out of the condenser. Usually there's a site glass somewhere so you can make sure you have a full color of liquid going to the metering device. I hope this answers your question. Good luck and thank you for watching!
@@AirConAcademy awesome man! I really appreciate you explaining this to me because this compressor is totally different from a regular little automobile compressor being that this '05g has six Pistons I will make a video of the RPMs of it running and show you the gauge pressures. I noticed the high pressure gauge was bouncing?
Sir u r amazing.....no words to thanks u....I was looking for months to clear my concept about unloading and loading ...u make me clear in just few minutes....thanks a lot ....God bless u
Thank you so much for your kind words! I'm so glad to hear that I was able to help you. I hope some of my other videos can also help you, keep learning out there! Thank you!!!
The unloaders on some manufacturers are energized for them to be loaded and on others they have to be de-energized, or another words no power going to them for them to be loaded and doing work. Depending on the age of the unit like an older units, they could be controlled through the thermostat. Then they were controlled through a Honeywell controller and these days they're controlled through circuit boards or computers that control the building temperature. I would start by looking at the schematic and see where the wires go to from the unloaders that are on the compressor. By tracing them back, you can see what is turning them on and off. I wish I could give you more information, but if they're not loading at the moment, you could check to see if they have voltage going to the unloader if they do, you can undo the voltage wires in that should load it up. And you could run it temporarily until you figure out how they are being turned on and off. Hope this helps! Thank you for watching. If you have any other questions, please shoot them my way!
Any vids on compound cooling? Started a new job at Walmart and some of their stores have compound compressors and I need to familiarize myself with them
I'm sorry, I am not sure what you mean by compound compressors? Are you talking about when you have multiple compressors and multiple evaporators? If that is the case I have a video on EPR valves. And how they are used to maintain different pressures and temperatures in evaporators. I'm not sure if this is what you were talking about. If you get a chance please let me know if that is what you were talking about or explain to me what you mean by compound cooling so I could possibly make a video of it. Thank you for your question!
It will not be that much warmer! If the cylinder head is hot you could have a blown gasket and hot gas is going into the low pressure side. How are your pressures? Do you have a high suction and low discharge pressure? This is one way to tell if you possibly have a leak. Good luck!
HA HA!!! Yes it is I don't like to read but I like teaching more then I dislike reading so I read so I can teach. If that makes any sense? and doing this so long I have also learned a lot out in the field. Thank you for watching!!!
Thank you so much! Thank you for your compliments and thank you for watching. I am not sure what you mean when you say pressure equalized? I believe you are talking about the pipe that is normally connecting two compressors when they run tandem Lee like in a chiller? One of the reasons they do this is because of the oil. As the compressor runs, it will pump some of the oil out because it mixes in with the refrigerant. As the suction Gas comes back, the oil is mixed in with it, and it would collect in only one of the compressors, if we did not have this equalization pipe between the two compressors. I hope this answers your question!!! And again, thank you for watching!
You are number one Can you tell me about Air compressor have unloader but is the that unloader work at same this operation or just discharge the air out to surrounding when unloading time(start and stop the compressor)?
Thank you and I'm glad you like the video! Air compressors they load and unload to keep the electric motor from drawing high amperage. Every time an electric motor starts up it draws high amperage and that cost money in electricity. Plus it puts stress on the motor. So it is best to just unload the air compressor so that the air is not being compressed and being dumped out so that you don't have the start and stop on air compressors. I hope this helps and again thank you for watching!
You are very welcome! I'm so glad to hear you say that you have learned a lot! I have been doing this for a while so I can feel myself on the way out! I'm glad you guys can come in and take over! Good luck and thank you for watching!
Nice video. What is the point with having a unloader valve on a 1 piston compressor, wouldnt it not be easier or cheaper to start/stop the compressor when the load in the room changes?
HA HA!!! I never tough of that about my video!!! In the drawing I am using, or showing a single piston compressor, just to make it easy for everyone to see how it works. But in reality, you are absolutely correct. You would never do that unless you are trying to keep the motor from starting and stopping. A long time ago, and I am talking about 30 years ago or so I did see that at one point. But that was the only time that I saw it, they were stopping the compressor from doing work, instead of stopping the entire motor. These days you would only use an unloader with two or three heads. And you would unload one or two heads and then shut the compressor off when it was satisfied and the last head would not use an unloader. But in the video I am just showing how the unloader works. It was interesting that you picked up on that. Thank you for watching!
@@AirConAcademy That was also my first intuition! Thanks for the answer again!! Keep up the good work. Just to be clear this is cind a the same principale when you are in the field and people are using the therm “the scroll is lifting” when having a digital unloader valve right on a scroll compressor?
@@cfcdomino on scroll compressors typically they are set up to operate at 100% or 67% capacity. There is a disc inside that rotates and it opens up some ports to reduce the capacity so the system can dehumidify. As far as I know when the scroll lifts is because there is a problem and it is doing that so that I can bring the temperature down, or to help liquid get through. I'll have to look into it but I don't think they lift to unload. Hope this answers your question. Thank you for watching!
Thank you for your question! We cannot say that the unloader, is energize when starting. Some manufacturers energize the unloader to load the compressor and others will deenergize the unloader to load the compressor. I suppose the correct way to put it is that when the compressor starts up, the compressor needs to be unloaded so that it will draw less inrush current and it will be easier to start up. Just remember, the compressor must be unloaded on start up and some manufactures energize the solenoid to have the compressor loaded and others will deenergize the solenoid to have the compressor loaded. Thank you for your question and I hope this answers your question. Thank you for watching!
So when my thermostat says "Stage 1, Stage 2, Stage 3" it's referencing how many unloaders are open? How do I determine whether an unloader is energized open or energized closed?
On older compressors, yes! It will tell you whether the compressor is loaded or unloaded and how many stages are actually doing work. On the newer ones than me adjust the speed of the motor/compressor! But if you have unloaders, you will have to hook up gauges and look at the pressures. So if your suction pressure drops when the the unloader has a magnetic field. Some manufacturers will energize the coil to be loaded. Others will deenergized the coil to be loaded. But you have to look at the pressures so you can make sure which way the manufacturer is doing it. If your pressure drop when there's a magnetic field, or the unloader solenoid is energized, then that means that they are energizing the solenoid for that to be loaded! Or in other words doing work. I hope this answers your question. And thank you for watching!
Some unloaders are built into the compressor. Look on the side or the front of the compressor there may be a capacity controller on there. What that is is a box that is part of the compressor there is a small adjustment valve stem under a cap. By adjusting this you can adjust it so that you can have it load or unload depending on the pressures. Most unloaders are going to be electrical like I am describing in the video. There's also a possibility that you may not have any type of unloader on your compressor. But take a look around the compressor see if it's in the front of the compressor or on the sides. Without looking at it it is difficult for me to tell you much more. Good luck!
Yes, it is important when the compressor starts because of the motor that drives the compressor. If the compressor starts fully loaded, it will be hard on the electric motor that drives the compressor. But if it is unloaded, then it is so much easier for the motor to start up. It has nothing to do with the compressor itself but with the electric motor that is driving the compressor. I hope this explains it for you. Thank you for your question and thank you for watching.!!!!
I have never worked on and ammonia system. Thank you for letting me know. I was not aware that ammonia was corrosive to motor windings! Thank you and thank you for watching!
I have an 06D compressor that will constantly have to pump itself down in the off cycle, like the valves are bad. Could the unloader be stuck causing this issue as well? If so how would I diagnose that?
It could be the unloader, it could be leaky valves, it could be a blown gasket. It could also be a leaky solenoid valve on the liquid line. From your description it sounds like you have a pump down system. Which means that it would have a solenoid valve on the liquid line and it would be the low pressure switch to cut the compressor off. One thing you could do is close off the suction valve to the condensing unit and see if the pressure increases or if it needs to pump itself down. If it pumps itself down then the problem could be with a compressor. If it does not pump itself down then it could be a leaky liquid line solenoid valve. Try this and hope that this will help you figure out if it is a leaky liquid line solenoid valve or if the problem is in the compressor. Good luck I hope you can figure it out!
I understand the heat load determines if the loaders are energised or not. What are some ways this happens? Is it communication with a room thermostat? Is it recording discharge air and is trying to maintain set point? I’m sure there’s a lot of ways to control them, but what are the most common? Thanks for the videos you are a great teacher
If you are fully Charge in 30 ton all ..what happen if 10 ton only running what about the pressure of the system it is coming high or we need to release some refrigerant or no
This is a complicated question. But let me try to make it short. When the compressor is unloaded the compressor will do less work like you said and the pressure will go up. When this happens the evaporator will do less work and because of that we are doing less cooling. At the same time the high side pressure drops because you're not pumping as much gas out. When the suction goes up and the discharge drops they work together to keep the system running properly. The refrigerant will stay in the system of course but most of the systems will have a TXV and because of that, the compressor will not flood and the evaporator will keep the proper amount of refrigerant in it. I hope this answers your question. Let me know if you still have questions.
@@AirConAcademy thanks for your answer sir. base on my experience regarding the tandem compressor, 2 compressor in one system.. if one compressor is running and charge for normal pressure low side ang high side... if the 2nd compressor is running or both compressor 1 & 2 is running suction pressure is drop and high pressure rise , then if you add refrigerant the in normal refrigerant charge for the system... and the one compressor is cut- off automatically and the other compressor is still running suction pressure is rise because the time both compressor is running I added a refrigerant and after cut -off one compressor the pressure is rise if one compressor is running suction pressure is increased.. I think it is same happen for undloader and tandem compressor.. I hope you understand my commen I am not good in English grammar...
@@Denzkitv yes, I understand your comment. And the way you described it it is correct. When you have unloaders the same thing happens as when you have two compressors in tandem. That is why the system has to be fully loaded, meaning the unloader has to be loaded so that you can get the correct pressures and you can figure out the correct superheat and sub cooling. Yes, you describe it correctly. So for charging, make sure you have a good heat load in the room that has been called and that you have the compressor fully loaded. Let me know if this makes sense to you. Good luck!
Very nice explanation sir and thanks Had one small query that what if the external solenoid loaded/unloaded is not used for compressor and all pistons are working loaded and will cut off only when the room temp reaches the desire temp set point by the LP and HP cut out, will it work normal if we remove the solenoid in emergency can we make it direct in some situations.
Yes if your compressor is fully loaded when the solenoid is de-energized and you remove the solenoid, then the compressor will always be loaded and it will operate without any problems. that is ok. thank you for your question.
That is a good question. Some are operated by oil pressure, some are operated by suction pressure, some are by demand. Meaning that if you need more cooling it will load up if you need less cooling it will unload and do less work.
some work differently than others. I was just trying to point out that. That the piston does not stop. Some will circulate the refrigerant from the high side into the low side, some keep the suction valve open and some keep the suction valve closed. It depends on the manufacture. But thank you! I appreciate your comment! And thank you for watching!
@@AirConAcademy yeah just checked the old CR1 from bitzer use suction shut off, the latest unloader design (CRII) from them uses Vapor diverting from him to low side i believe. They also pulse the unloading solenoid to achieve near stepless capacity control! Awesome stuff thanks
@@VoiD1x thanks! I keep telling everyone that technology is changing so fast it is crazy! I don't think anyone has any idea what is going to be happening in five or 10 years!? Thanks! Take care!
Thanks for the information. Every now and then I come across unloaders. I understand the concept of what their function is but was not sure how I would go about troubleshooting if I came across a bad unloader. Knowing how your pressures regulate unloaded and loaded helps especially when there are 3 or 4 unloaders on a comp. Constant cycling of the compressor would probably indicate that the unloaders aren't doing their job.
Yes, that could be an indication. You should check to see if the unloaders are unloading before the compressor shuts off. I mean it should be fully unloaded before it shuts off. Unloaders work great and it minimizes the constant starting up and shutting off of the compressor.
The one you told about 24v electric type of solenoid valve,need to ask something,means how 24v supply is given n removed,who decides...means how this happens
24 voltage is sent to the coil and that is what energizes and de-energizes the coil. But this voltage is controlled to various ways. One way is through a thermostat that has several cooling stages. Meaning that stage one during the compressor on and stage two will load and unload the unload. At other buildings it is done through the electronics that control the temperature throughout the building. I have also seen it where the unloader works off of suction pressure and oil pressure. So as the suction pressure drops they know they need less cooling and they unload, the same with the oil pressure when the oil pressure drops they know they need less cooling and the unload. It is hard to give you just one quick answer as to how that is controlled. Thank you for watching that question!
No, it should not cost it to go out on high head. It will just make the compressor work at its maximum capacity, which is it's original design. if you're having a system that is going out on high head, check your condenser and make sure it is clean he might even want to use a flashlight to look in between the fins, make sure that someone has not replaced the condenser fan motor with a slower, running fan, make sure that the condenser fan is rotating and the proper direction for the fan blade, make sure he has not been overcharged or that there's a restriction. I hope this helps. And thank you for watching!
Thank you! Yes, they are so they can control the capacity of the systems. some of the guys I have met have never seen unloaders. That seems to give them an understanding as to how they work. Thank you, and thank you for watching!
Yes! It is OK if it unloads during the night. It should load and unload automatically depending on the heat load. In other words if you do not need as much cooling it should unload and it will cost less to run but maintain the proper temperature. If you do not need it it is OK to turn it off. But it will automatically adjust to maintain the proper temperature/setpoint. Thank you for watching and thank you for sending in your question!
I'm glad you enjoyed the video and the rotary compressor is one type of compressor. The screw compressor is a different type of compressor. The rotary compressors are used on smaller units and they can adjust the speed of these motors/compressors to adjust the capacity. This way you can change the capacity by adjusting the speed. On the screw compressors, those are used mostly on large chillers, which are designed to cool buildings down. These are single speed, but they use a slide to control how much refrigerant is going into the compressor to adjust the capacity/tonnage. Normally people do not mess with these compressors, unless they really, really know what they are doing. I hope this answers your question. And thank you for watching!
@@AirConAcademy Us ammonia guys have it cut out for us. Thank you for the tidbits of information and your wonderful videos, I’ll definitely be subscribing. I was curious because I have a compressor leaking from the unloader solenoid and I was unfamiliar with how they unloaded.
Great video! When adding refrigerant to a system, the compressor should be loaded. Typically, on an 06 e/d Carlyle, should the unloaders be ran in or out to be loaded?
Yes, that is the only way to get the charge correct. To make sure the system is fully loaded. I don't know how your unloaders are set up but make sure that the unit is calling for full cooling so that the unloaders will be loaded. You will see that the pressures will change. The suction pressure will drop and discharge pressure will increase. Only then will you be able to get a charge correct. Hope this helps.
Very well explained. One question, when unloaders are energized and the port to suction is open all the time, doesn't this raise the low side pressure? Meaning that all that gas is flowing backwards to the evap?
Basically, all valves to and from the compressor have to be closed in order for psi to build or get higher. This is because the compressor takes for example 10 ounces of space and compresses it into 2 ounce of space. If the suction side valve is open and the piston is moving up and down I have all that space from the compressor piston all the way back to the evaporator coil. This can be for example 100 ounces. The compressor now with the unloader operational is taking 110 ounces of space and compressing it into 102 ounces. This will barely raise the psi in the system and wont affect the flow of refrigerant. 10 ounces down to 2 ounces causes refrigerant to go from 10 psi to 100 psi 110 ounces down to 2 ounces causes refrigerant to go from 10 psi to 11 psi. If you think about that, 110 psi compared to 11 psi, the discharge side of the compressor is so much higher than the suction side. Basically this difference in pressure wont matter to the flow of refrigerant and your system will work. Even if you were able to have some flow of refrigerant from the suction side to the evaporator there would be a check valve installed on the system that would make sure that you have the proper flow. Try to think about the volume that the compressor has when both valves are closed and how much it can compress vs when the unloader forces it open and you have a large area/volume that cant really be compressed.
our unloader starts with 24vdc. after i press start on d compressor, what happen 2 d unloader? does it close n open on piston operation until it reach the high pressure and open up to the discharge pressure?
ronnie corpin Typically the compressor will start with that cylinder unloaded. Meaning that the piston will move but it would not do any compressing or work. It does that to keep the amp draw down and so that it is easier on the compressor motor. After a few seconds some manufacturers will remove the volts from the unloader so that it will load up and the valves will start to do some work, meaning the cylinder will actually be compressing refrigerant. You will notice the suction pressure is going to drop and discharge pressure is going to rise. When you do not need as much cooling, it will add the 24 V DC like in your case so it will stop the compression action. Most places/compressors use 24 V AC.
ronnie corpin are you saying the compressor runs for about 45 seconds? And then the compressor tripped and shuts off? Are you saying that you added refrigerant to the system? Or are you saying the pressures increase?
@@AirConAcademy the compressor stops running after 45secs...and we have a high temp discharge of 190 deg F. also an alarm saying high condenser temp after adding freon.
Wow! That is very hot! In my area we do not see temperature is that high! Near WASHINGTON DC. My suggestion is to make sure the condenser coil is clean, this way you get rid of as much heat as possible as easy as possible. Another thing I would suggest, and this is typically not done but it is some thing I have found that helps in very high temperatures, that is to run the liquid line and the suction line together and have them insulated. By doing this you are sub cooling the refrigerant even more before it gets to the metering device and you are keeping the refrigerant sub cool. The problem with this is that you will have to monitor the superheat at the compressor to make sure you are not overheating the compressor. As you run the liquid line and suction line together they need to be very well insulated to keep them away from the heat from the ambient air. One other thing I would check to make sure that I do have plenty of airflow on the condenser side so that I can remove as much heat as possible and keep the high side pressure low. I hope this helps and thank you for sending the question.
Sir, Could you please explain on below also, 1. What is High Suction Superheat? What will be the Problems? Solution? 2. Suction Temperature high and low limits and what problems it may cause? 3. Discharge Temperature limits and problems? 4. Reason for liquid or knocking? Thanks alot Sir.
1. High suction superheat is when you have the suction gas coming back to the compressor and it is too warm. If it is too warm, it is not going to call the compressor down like it should and the compressor might overheat and tripped on internal overload. 2. Just like I said, before if you have high temperature on the suction line. It will affect the compressor the valves because of the high superheat may overheat, specially the discharge valve and you could destroy those discharge valves. I'm not sure what you mean by love limits. But if the suction pressure is too low, your compression ratio will be high and that will work the compressor very hard then again, overheat or destroy a compressor. 3. If your temperature is high on the high side, you are going to damage the discharge valves up and they will leak and because of that you compressor is not going to move refrigerant like it should. We need to make sure the compressor stays full so it will last a long time. 3. Typically liquid came back to the compressor is going to give you the liquid knocking you were talking about. If you do not have superheat, then that will cause this problem you're talking about and kill a compressor. That's why you must have the proper amount of superheat. I hope this answers your questions. You should take a look at my webpage, airconacademy.com, where I have some courses and explain all of this. Thank you for watching and for sending these messages over to me. Good luck out there!
There are many different ways to energize and de-energize the solenoid. It can be done with a two or three stage thermostat. It can also be controlled by suction pressure or oil pressure. As the low decreases the suction pressure will drop and the oil pressure will also drop by monitoring this I have seen that they have controlled the loading and unloading of compressors. The easiest way is like I mentioned above by using a thermostat. As the load increases the thermostat would load another bank of cylinders doing more cooling, as the heat low drops it would unload the cylinder so that it is not doing that much work. And do less cooling. I hope this makes sense. I hope this explains it to you. Good luck.
@9:04 u r explaining that with loading and unloading suction and discharge pressure changes what I think is, consider an example, we have R404 in our system and require temp is 4 deg C , to achieve this we need suction pressure around 60psig , if heat load increase this evaporator's pressure goes down(i.e. suction pressure) and to maintain the pressure 60psig load on compressor increases and it will activate another bank of cylinder and when load decrease it will unload the bank. This is how loading and unloading works. AND you are explaining that the pressure difference changes with loading and unloading but we have to maintain pressure in evaporator to maintain constant Temp.
yes you want to maintain around 4C as the load increases the evaporator pressure or suction pressure should increase not drop, but when the compressor loads up that is when the suction pressure would drop to keep the pressure where it should be 60PSI so it can stay around 4C. As the load decreases or the room temperature drops it will automatically unload. and yes every time the cylinder loads up (or it is doing work) the pressure should drop and when it is NOT doing work the pressure will increase.
I appreciate your time and effort. I have a question please yesterday I had question in my head that what would happen to a compressor if it runs on negative pressure for example ( low pressure switch incorrectly set) so that the compressor below atmospheric pressure runs. many greetings from Germany
YES!!!! The low pressure switch is either not set properly or it is bypassed. make sure it is not happening because that will kill a compressor very easily!!! it will run with no refrigerant gas to cool it and it will fail
i've been in the hvac business for 19 years, but mostly residential and light commercial. i've never really understood unloaders until i watched your video. thanks so much for sharing this
I'm so glad that my video helped you understand unloaders! Thank you so much for your kind words and I am so glad I could help! Thank you and keep learning out there!
Soil heavsystom gas potavting systom soild conrold mechionom sely gas insidd pards dsmgd sdlfeyunlored opn coglod moregax powed edom potacting inside parts slftg valplat hedpate pidon all poractinv sydtim rightedunlored pudhinschion t go oponvslvd op pas dis tbuitng systo motr aut msticsl off self gax lord inde nog pas sinv hevey equpited ok
@@jollyscaria1922 hi, I am not sure what you're trying to say. I wish I could help you. If you could please try again. Thank you.
This professor takes his time and teaches. I can retain the knowledge quicker, when it’s taught that way.
Wow! Thank you so much for your kind words! I love teaching, and it gets me motivated even more when I know I'm helping you guys out there! Thank you for watching!
Today I understand 100% loading and unloading of compressor
Thank you so much! I really appreciate comments like this! It took me a while to make this video because I do all of this myself. I'm glad I could help! Good luck out there! And keep learning!
Very simple clear and nice way explained thanku lot
Thank you!!!! I am glad you liked the video!!!
Thanks so much, I can't expect a better teacher than u, you are an excellent person. God bless you.
Thank you so much for your kind words! I really, really appreciate your comments! And thank you for watching!
He was my HVAC teacher. Very knowledgeable and a very good teacher.
Thank you!!!
What city and state????
@@TheSkunk1996 Virginia
l'm from Indonesian you're best
Hats off to you sir. You sir just made my life a lot easier.
Thank you! I'm so glad to hear that. That's why I make these videos, I want to help you guys out there! I'm glad you liked the video and thank you for watching!
Very nicely explained Sir thank you
Thank you and thank you for watching!
Super explanation.Appreciated
You're welcome! I'm glad you enjoyed the video and thank you for watching!
To check if you have power at a solenoid you can also rest your amp meter on the magnet and see if it is drawing amps. Thank you for the video!
Thank you!!!
Great explanation mate, I have a learning disability and that made sense to me, thank you so much
I'm glad you like the video and I am glad that it made sense to you! Keep watching the videos and maybe the other ones will help some more! Good luck out there!
Thanks You. I have seen a solenoid upon compressor bitzer but is connected with tube. Too is a discharger ?
I am not sure without actually looking at it, but it sounds like it may still be part of an unloader. There are so many different configurations out there with a short description it is hard to tell. I'm sorry
@@AirConAcademy thank you.
Thank you for sharing your knowledge. You make great videos
Thank you so much! I really appreciate your comments, and I hope to make some more soon!
I can tell he is a great teacher!!!! Well done
Thank you!!!!!
Am Godfrey Ssemagobwe from Uganda, sir I really appreciate the much effort you put in teach us more about refrigeration and air-condition, if all goes well I will be attending online course from your Academy. It is really interesting sir.
Thank you so much!!! It is comments and people like you that make me want to do more!!! I hope to see you in class soon. Thank you!!!
You deserves a wow👌🏻
But expansion valve is also doing this same principle right?, it also limits the refrigerant base on superheat.
Thank you so much!!!!
The TXV is controlling the refrigerant going in to the evaporator, this is controlling the refrigerant going in to the compressor so you can adjust the capacity of the unit or the compressor. so you can turn the unit in to a 10 ton in stead of a 15 ton and back in to a 15 in case you need more cooling. I hope this answers your question? and Thank you so much for the kind words. thank you for watching.
@AirConAcademy we can control the cooling by txv adjustment if it's electronically controlled txv based on temp, so by unloading the compressor also we're reducing the cooling performance, right?
Only difference is if we reduce compressor load , energy is saved extra , right????
@@bt9604 by adjusting the TXV, even if you are using an electronically controlled TXV, you are only adjusting the super heat in the evaporator. You are not adjusting the room temperature. A lot of times when you have an electronic expansion valve. The compressor is going to be an inverter unit, meaning that as the electronic expansion valve adjust or let's say closes the comp is going to slow down also. So it is not just a matter of adjusting the expansion valve. We have to worry about what the compressor is doing also. The unloader is actually going to adjust capacity of the compressor to meet the load demand. So it will turn a 30 ton compressor into only a 20 ton compressor, or maybe even a compressor depending on the application. if you do not adjust the speed of the compressor and you close the TX some your evaporator temperature will drop and it could freeze the coil because compressor speed was not adjusted.
Hopefully this explains your question?
@AirConAcademy thanks🫡
Great video buddy , you help me understand my job and I just wanted to say thank you💪🏻
Thank you for the wonderful comment! That's why I do these to help you guys out there. Thank you for watching!
What a fantastic explanation. You are a great teacher and definitely it comes through a lot of experience and high educational background. Thank you for sharing. I liked your video.
It's very comfortable to understand you sir.. thank you so much
Thank you so much! I really appreciate your comment!
Good explanation.
I used to work with these compressors, Carrier model O5G 6 cylinders in motor coaches. They were belt driven by the bus engine.
When the unloader coil on a head. was electrically energized, those cylinders were unloaded.
Lots of guys were confused by this.
You could actually feel each side of the outer heads and sense a temperature difference from one side to the other. Low side, high side.
I would watch the needles on the gauges "jump" when the unloader went from energized to densrgized.
Yes, you are correct. A lot of guys get confused with the loading and unloading and with the pressures rising and falling as it loads and unloads. I am glad he liked the video. Thank you for watching!
Could you please explain the oil flow in the compressor where there is oil pump to maintain oil pressure.
What could be the differential oil pressure in the system and how it is maintained? Basically please try explain all the points related oil pressure and oil flow. Thanks alot.
Oil is pulled out of the oil sump at the bottom of the compressor, the oil pump that is at the front of the compressor will pump it through the crankshaft, because the crankshaft is hollow, the crankshaft has holes in it where the bearings are, so as the pump pulls the oil out of the oil sump it pumps it into the shaft and through the holes and it lubricates the bearings as it lubricates the oil falls back down to the oil sump to be used again.
I hope this explains it. Thank you for watching!
@@AirConAcademy Thank you so much Sir.
I have watched a lot of technical teachers on compressors, on you tube. Some would talk and talk and include practical works and the more you try to learn from them, to mire confused you become. But in your case your explanation is very clear and easily understood. I'm a factory owner in west Africa. I handle heavy industrial and commercial equipments and have large stock from Copland, Carrier, Hitachi, Bitzer, Duareen etc. I build blasting units, cold storage facilities, as well as air Condition commercial and residential buildings. I would like to watch more of your videos, as well as share Ideas. Thanks.
Thank you so much for your kind words. I am so glad that I can help people understand how things work. please tell your friends and co workers about these videos and have them subscribe to my channel. If you have any suggestions for videos please send me a message. Thank you
Very well explained. He knows the topic.
Thank you so much! I’m glad you liked it. I hope I can get some other videos online soon.
This was great man. Great flow and articulation. I learned.
Thank you so much for your kind words! I enjoyed teaching, so I am so glad that I could help! If you get a chance, check out my webpage airconacademy.com I know I did not like school because I did not have any teachers that could actually teach. I enjoyed teaching so I think that makes a difference. Thank you for watching!
Hey brother, I just worked on a bus with a '05G compressor. It runs on r134a There are two valves located on it. Do you know if they need to be turned all the way in for it to be open or do they need to be turned all the way out for it to be open? And also what should be the running pressure at 100° f? The charts do not make sense because I compare it with other r134a compressors on smaller vehicles and they are way different? The '05g compressor is running at 70 psi on the low suction side and 225 on the high side at 100° f
The two valves you are talking about are they suction service valve and the discharge service valve. Those valves need to be opened all the way to where it is called back seated. When they are all the way to the back, you will not have access, or you will not be able to read precious when you hook up gauges. If you want to pressures at the compressor then, they should be with the mid position or cracked. That means that they are off of the backseat. If you close the valves completely, then they are considered front seated, and the compressor will not run because there will be no flow of refrigerant through it. Those pressures are giving me seem to be pretty close. Do you have a site glass anywhere on the liquid line or on the receiver/dryer? Do you want to make sure you have enough subcooling and with the bus running a different speed your pressures are going to change. As the bus speeds up the engine wraps up, which is going to turn that compressor faster and change your pressures. So you need to make sure you have sub cooling coming out of the condenser. Usually there's a site glass somewhere so you can make sure you have a full color of liquid going to the metering device. I hope this answers your question. Good luck and thank you for watching!
@@AirConAcademy awesome man! I really appreciate you explaining this to me because this compressor is totally different from a regular little automobile compressor being that this '05g has six Pistons I will make a video of the RPMs of it running and show you the gauge pressures. I noticed the high pressure gauge was bouncing?
@@SMOKEY-JAYS-DIESEL great! If you do that, I would love to see it! You can send it to me to my email address. jh@airconacademy.com
I like it sir your way of teaching is excellent sir you make it simple sir
Thank you!!!! I am glad you like it!!!!
Sir u r amazing.....no words to thanks u....I was looking for months to clear my concept about unloading and loading ...u make me clear in just few minutes....thanks a lot ....God bless u
Thank you so much for your kind words! I'm so glad to hear that I was able to help you. I hope some of my other videos can also help you, keep learning out there! Thank you!!!
Sir , I appreciate all your videos , very informative
Noel Baracho Thank you! I hope they help.
Tnx for sharing knowledge
My compressors won't go 2nd and 3rd stage any ideas?
The unloaders on some manufacturers are energized for them to be loaded and on others they have to be de-energized, or another words no power going to them for them to be loaded and doing work. Depending on the age of the unit like an older units, they could be controlled through the thermostat. Then they were controlled through a Honeywell controller and these days they're controlled through circuit boards or computers that control the building temperature. I would start by looking at the schematic and see where the wires go to from the unloaders that are on the compressor. By tracing them back, you can see what is turning them on and off. I wish I could give you more information, but if they're not loading at the moment, you could check to see if they have voltage going to the unloader if they do, you can undo the voltage wires in that should load it up. And you could run it temporarily until you figure out how they are being turned on and off. Hope this helps! Thank you for watching. If you have any other questions, please shoot them my way!
This video give me all understanding about the unloader thank you very much for your teaching God Bless
I am glad I can help!!!
my salute to you sir .. I see your presentation , i improve myself so much .
Thank you!!!! I am so glad I can help!!!!
really awesome. everybody can easy to understand how this system works. thank you sir
Any vids on compound cooling? Started a new job at Walmart and some of their stores have compound compressors and I need to familiarize myself with them
I'm sorry, I am not sure what you mean by compound compressors? Are you talking about when you have multiple compressors and multiple evaporators? If that is the case I have a video on EPR valves. And how they are used to maintain different pressures and temperatures in evaporators. I'm not sure if this is what you were talking about. If you get a chance please let me know if that is what you were talking about or explain to me what you mean by compound cooling so I could possibly make a video of it. Thank you for your question!
Great sir it's awesome video knowledge for technicians
Thank you!!!
Excellent explanation ! Thank you very much !
Thank you! And thank you for watching!
Really it was amazing now only i knew that roll of loading and unloading from the system really great thank you so much
Thank you for your comment! And I'm glad I could help! Thank you for watching!
Very well explained! Big thumbs up!
Thank you so much! And thank you for watching!
Will an unloaded cylinder head be hotter than a pumping one since there's no cold return refrigerant flowing through?
It will not be that much warmer! If the cylinder head is hot you could have a blown gasket and hot gas is going into the low pressure side. How are your pressures? Do you have a high suction and low discharge pressure? This is one way to tell if you possibly have a leak. Good luck!
Thanks mate. It's better than the textbook reading.
HA HA!!! Yes it is I don't like to read but I like teaching more then I dislike reading so I read so I can teach. If that makes any sense? and doing this so long I have also learned a lot out in the field. Thank you for watching!!!
This is amazing! Very knowledgeable n good explanation! U r my great instructor 👍can u explain why compressor need pressure equalized ？please!
Thank you so much! Thank you for your compliments and thank you for watching. I am not sure what you mean when you say pressure equalized? I believe you are talking about the pipe that is normally connecting two compressors when they run tandem Lee like in a chiller? One of the reasons they do this is because of the oil. As the compressor runs, it will pump some of the oil out because it mixes in with the refrigerant. As the suction Gas comes back, the oil is mixed in with it, and it would collect in only one of the compressors, if we did not have this equalization pipe between the two compressors. I hope this answers your question!!! And again, thank you for watching!
You are number one
Can you tell me about Air compressor have unloader but is the that unloader work at same this operation or just discharge the air out to surrounding when unloading time(start and stop the compressor)?
Thank you and I'm glad you like the video! Air compressors they load and unload to keep the electric motor from drawing high amperage. Every time an electric motor starts up it draws high amperage and that cost money in electricity. Plus it puts stress on the motor. So it is best to just unload the air compressor so that the air is not being compressed and being dumped out so that you don't have the start and stop on air compressors. I hope this helps and again thank you for watching!
Thank you so much I’ve learned a lot really appreciated.
You are very welcome! I'm so glad to hear you say that you have learned a lot! I have been doing this for a while so I can feel myself on the way out! I'm glad you guys can come in and take over! Good luck and thank you for watching!
Nice video. What is the point with having a unloader valve on a 1 piston compressor, wouldnt it not be easier or cheaper to start/stop the compressor when the load in the room changes?
HA HA!!! I never tough of that about my video!!! In the drawing I am using, or showing a single piston compressor, just to make it easy for everyone to see how it works. But in reality, you are absolutely correct. You would never do that unless you are trying to keep the motor from starting and stopping. A long time ago, and I am talking about 30 years ago or so I did see that at one point. But that was the only time that I saw it, they were stopping the compressor from doing work, instead of stopping the entire motor. These days you would only use an unloader with two or three heads. And you would unload one or two heads and then shut the compressor off when it was satisfied and the last head would not use an unloader. But in the video I am just showing how the unloader works. It was interesting that you picked up on that. Thank you for watching!
@@AirConAcademy That was also my first intuition! Thanks for the answer again!! Keep up the good work. Just to be clear this is cind a the same principale when you are in the field and people are using the therm “the scroll is lifting” when having a digital unloader valve right on a scroll compressor?
@@cfcdomino on scroll compressors typically they are set up to operate at 100% or 67% capacity. There is a disc inside that rotates and it opens up some ports to reduce the capacity so the system can dehumidify. As far as I know when the scroll lifts is because there is a problem and it is doing that so that I can bring the temperature down, or to help liquid get through. I'll have to look into it but I don't think they lift to unload. Hope this answers your question. Thank you for watching!
Well done, kept it simple and easy.
Sir does the unloader always energize when compressor is running or only energize when starting.
Thank you for your question! We cannot say that the unloader, is energize when starting. Some manufacturers energize the unloader to load the compressor and others will deenergize the unloader to load the compressor. I suppose the correct way to put it is that when the compressor starts up, the compressor needs to be unloaded so that it will draw less inrush current and it will be easier to start up. Just remember, the compressor must be unloaded on start up and some manufactures energize the solenoid to have the compressor loaded and others will deenergize the solenoid to have the compressor loaded. Thank you for your question and I hope this answers your question. Thank you for watching!
So when my thermostat says "Stage 1, Stage 2, Stage 3" it's referencing how many unloaders are open? How do I determine whether an unloader is energized open or energized closed?
On older compressors, yes! It will tell you whether the compressor is loaded or unloaded and how many stages are actually doing work. On the newer ones than me adjust the speed of the motor/compressor! But if you have unloaders, you will have to hook up gauges and look at the pressures. So if your suction pressure drops when the the unloader has a magnetic field. Some manufacturers will energize the coil to be loaded. Others will deenergized the coil to be loaded. But you have to look at the pressures so you can make sure which way the manufacturer is doing it. If your pressure drop when there's a magnetic field, or the unloader solenoid is energized, then that means that they are energizing the solenoid for that to be loaded! Or in other words doing work. I hope this answers your question. And thank you for watching!
Very nice information from you bro
Thank you so much! I'm glad you like the video! Keep learning and be safe out there!
how to adjust a manual unloader no solenoid valve my unit is a 30 ton and I need to adjust to 20 ton..
Some unloaders are built into the compressor. Look on the side or the front of the compressor there may be a capacity controller on there. What that is is a box that is part of the compressor there is a small adjustment valve stem under a cap. By adjusting this you can adjust it so that you can have it load or unload depending on the pressures. Most unloaders are going to be electrical like I am describing in the video. There's also a possibility that you may not have any type of unloader on your compressor. But take a look around the compressor see if it's in the front of the compressor or on the sides. Without looking at it it is difficult for me to tell you much more. Good luck!
Brazil here.
Thanks.
Thank you for letting me know! I was wonder where everyone is from! And I hope it helped!
Thanks sir u are really excellent teacher take care.
Ali imran thank you!!!!
Loved your explanation, Thanks.
Thank you so much! And thank you for watching!
Hi Sir, Why is unloading important when the compressor starts?
Can you please explain.
Yes, it is important when the compressor starts because of the motor that drives the compressor. If the compressor starts fully loaded, it will be hard on the electric motor that drives the compressor. But if it is unloaded, then it is so much easier for the motor to start up. It has nothing to do with the compressor itself but with the electric motor that is driving the compressor. I hope this explains it for you. Thank you for your question and thank you for watching.!!!!
@@AirConAcademy Thanks alot Sir.
Open Compressors are also used for Ammonia systems. Ammonia is corrosive to motor windings.
I have never worked on and ammonia system. Thank you for letting me know. I was not aware that ammonia was corrosive to motor windings! Thank you and thank you for watching!
Good demonstration.
Thank yo and thank you for watching!!!
I have an 06D compressor that will constantly have to pump itself down in the off cycle, like the valves are bad. Could the unloader be stuck causing this issue as well? If so how would I diagnose that?
It could be the unloader, it could be leaky valves, it could be a blown gasket. It could also be a leaky solenoid valve on the liquid line. From your description it sounds like you have a pump down system. Which means that it would have a solenoid valve on the liquid line and it would be the low pressure switch to cut the compressor off. One thing you could do is close off the suction valve to the condensing unit and see if the pressure increases or if it needs to pump itself down. If it pumps itself down then the problem could be with a compressor. If it does not pump itself down then it could be a leaky liquid line solenoid valve. Try this and hope that this will help you figure out if it is a leaky liquid line solenoid valve or if the problem is in the compressor. Good luck I hope you can figure it out!
Amazing lesson, thank you.
Thank you so much! And thank you for watching!
Best of all time ....thanks.
Wow! Thank you so much for the kind words. I'm glad you enjoyed the video and thank you for watching!
I understand the heat load determines if the loaders are energised or not. What are some ways this happens? Is it communication with a room thermostat? Is it recording discharge air and is trying to maintain set point? I’m sure there’s a lot of ways to control them, but what are the most common?
Thanks for the videos you are a great teacher
If you are fully Charge in 30 ton all ..what happen if 10 ton only running what about the pressure of the system it is coming high or we need to release some refrigerant or no
This is a complicated question. But let me try to make it short. When the compressor is unloaded the compressor will do less work like you said and the pressure will go up. When this happens the evaporator will do less work and because of that we are doing less cooling. At the same time the high side pressure drops because you're not pumping as much gas out. When the suction goes up and the discharge drops they work together to keep the system running properly. The refrigerant will stay in the system of course but most of the systems will have a TXV and because of that, the compressor will not flood and the evaporator will keep the proper amount of refrigerant in it. I hope this answers your question. Let me know if you still have questions.
@@AirConAcademy thanks for your answer sir. base on my experience regarding the tandem compressor, 2 compressor in one system.. if one compressor is running and charge for normal pressure low side ang high side... if the 2nd compressor is running or both compressor 1 & 2 is running suction pressure is drop and high pressure rise , then if you add refrigerant the in normal refrigerant charge for the system... and the one compressor is cut- off automatically and the other compressor is still running suction pressure is rise because the time both compressor is running I added a refrigerant and after cut -off one compressor the pressure is rise if one compressor is running suction pressure is increased..
I think it is same happen for undloader and tandem compressor..
I hope you understand my commen I am not good in English grammar...
@@Denzkitv yes, I understand your comment. And the way you described it it is correct. When you have unloaders the same thing happens as when you have two compressors in tandem. That is why the system has to be fully loaded, meaning the unloader has to be loaded so that you can get the correct pressures and you can figure out the correct superheat and sub cooling. Yes, you describe it correctly. So for charging, make sure you have a good heat load in the room that has been called and that you have the compressor fully loaded. Let me know if this makes sense to you. Good luck!
Good teacher I like his style
Thank you!!!! I am glad you liked it!!!!
Omg its awesome its so easy to understand my teacher doesnot describe like this
Very nice explanation sir and thanks
Had one small query that what if the external solenoid loaded/unloaded is not used for compressor and all pistons are working loaded and will cut off only when the room temp reaches the desire temp set point by the LP and HP cut out, will it work normal if we remove the solenoid in emergency can we make it direct in some situations.
Yes if your compressor is fully loaded when the solenoid is de-energized and you remove the solenoid, then the compressor will always be loaded and it will operate without any problems. that is ok. thank you for your question.
Great knowledge shared. THANKS. I will like to exactly how the unloader coil is activated. Does it have anything to do with suction pressure?
That is a good question. Some are operated by oil pressure, some are operated by suction pressure, some are by demand. Meaning that if you need more cooling it will load up if you need less cooling it will unload and do less work.
@@AirConAcademy Thanks for sharing. I look for to more especially on animations. Keep up the good work.
I believe the bitzer head unloaders shut the suction valve as per bitzer manual KT-100, thoughts?
some work differently than others. I was just trying to point out that. That the piston does not stop. Some will circulate the refrigerant from the high side into the low side, some keep the suction valve open and some keep the suction valve closed. It depends on the manufacture. But thank you! I appreciate your comment! And thank you for watching!
@@AirConAcademy yeah just checked the old CR1 from bitzer use suction shut off, the latest unloader design (CRII) from them uses Vapor diverting from him to low side i believe. They also pulse the unloading solenoid to achieve near stepless capacity control!
Awesome stuff thanks
@@VoiD1x thanks! I keep telling everyone that technology is changing so fast it is crazy! I don't think anyone has any idea what is going to be happening in five or 10 years!? Thanks! Take care!
Thanks for the information. Every now and then I come across unloaders. I understand the concept of what their function is but was not sure how I would go about troubleshooting if I came across a bad unloader. Knowing how your pressures regulate unloaded and loaded helps especially when there are 3 or 4 unloaders on a comp. Constant cycling of the compressor would probably indicate that the unloaders aren't doing their job.
Yes, that could be an indication. You should check to see if the unloaders are unloading before the compressor shuts off. I mean it should be fully unloaded before it shuts off. Unloaders work great and it minimizes the constant starting up and shutting off of the compressor.
Great video, simple and to the point.
Thank you!!!! I am glad you liked it!!!
Love your explanation ❤
Thank you so much for your kind words! I'm glad you like the video and thank you for watching!
The one you told about 24v electric type of solenoid valve,need to ask something,means how 24v supply is given n removed,who decides...means how this happens
24 voltage is sent to the coil and that is what energizes and de-energizes the coil. But this voltage is controlled to various ways. One way is through a thermostat that has several cooling stages. Meaning that stage one during the compressor on and stage two will load and unload the unload. At other buildings it is done through the electronics that control the temperature throughout the building. I have also seen it where the unloader works off of suction pressure and oil pressure. So as the suction pressure drops they know they need less cooling and they unload, the same with the oil pressure when the oil pressure drops they know they need less cooling and the unload. It is hard to give you just one quick answer as to how that is controlled. Thank you for watching that question!
Excellent teacher.
Thank you so much! I'm glad you like the video and I'm glad to help!
If the unloaders stop working can it cause a system to go off on high head pressure?
No, it should not cost it to go out on high head. It will just make the compressor work at its maximum capacity, which is it's original design. if you're having a system that is going out on high head, check your condenser and make sure it is clean he might even want to use a flashlight to look in between the fins, make sure that someone has not replaced the condenser fan motor with a slower, running fan, make sure that the condenser fan is rotating and the proper direction for the fan blade, make sure he has not been overcharged or that there's a restriction. I hope this helps. And thank you for watching!
They're used all the time in rack refrigeration
Thank you! Yes, they are so they can control the capacity of the systems. some of the guys I have met have never seen unloaders. That seems to give them an understanding as to how they work.
Thank you, and thank you for watching!
i have a question sir. the chiller that i operated now got unloading during midnight. is it okay when i turning off the chiller? or stay it running?
Yes! It is OK if it unloads during the night. It should load and unload automatically depending on the heat load. In other words if you do not need as much cooling it should unload and it will cost less to run but maintain the proper temperature. If you do not need it it is OK to turn it off. But it will automatically adjust to maintain the proper temperature/setpoint. Thank you for watching and thank you for sending in your question!
Thank you so much for the video! Very informative. How does this translate to a rotary screw compressor?
I'm glad you enjoyed the video and the rotary compressor is one type of compressor. The screw compressor is a different type of compressor. The rotary compressors are used on smaller units and they can adjust the speed of these motors/compressors to adjust the capacity. This way you can change the capacity by adjusting the speed. On the screw compressors, those are used mostly on large chillers, which are designed to cool buildings down. These are single speed, but they use a slide to control how much refrigerant is going into the compressor to adjust the capacity/tonnage. Normally people do not mess with these compressors, unless they really, really know what they are doing. I hope this answers your question. And thank you for watching!
@@AirConAcademy Us ammonia guys have it cut out for us. Thank you for the tidbits of information and your wonderful videos, I’ll definitely be subscribing. I was curious because I have a compressor leaking from the unloader solenoid and I was unfamiliar with how they unloaded.
@@blaine4754 thank you! A lot of times every little bit of information helps! Thank you for watching!
Thanks for lot and very good teach
Thank you very much! And thank you for watching!
Great video! When adding refrigerant to a system, the compressor should be loaded. Typically, on an 06 e/d Carlyle, should the unloaders be ran in or out to be loaded?
Yes, that is the only way to get the charge correct. To make sure the system is fully loaded. I don't know how your unloaders are set up but make sure that the unit is calling for full cooling so that the unloaders will be loaded. You will see that the pressures will change. The suction pressure will drop and discharge pressure will increase. Only then will you be able to get a charge correct. Hope this helps.
Thank you so much for sharing your knowledge
Very good teacher nice
Thank you so much! I really appreciate your comment and thank you for watching!
thanks, i really understood how an unloader works.
Thank you so much! I am glad. That's why I do this to pass this information on!
Very well explained. One question, when unloaders are energized and the port to suction is open all the time, doesn't this raise the low side pressure? Meaning that all that gas is flowing backwards to the evap?
Basically, all valves to and from the compressor have to be closed in order for psi to build or get higher. This is because the compressor takes for example 10 ounces of space and compresses it into 2 ounce of space. If the suction side valve is open and the piston is moving up and down I have all that space from the compressor piston all the way back to the evaporator coil. This can be for example 100 ounces. The compressor now with the unloader operational is taking 110 ounces of space and compressing it into 102 ounces. This will barely raise the psi in the system and wont affect the flow of refrigerant.
10 ounces down to 2 ounces causes refrigerant to go from 10 psi to 100 psi
110 ounces down to 2 ounces causes refrigerant to go from 10 psi to 11 psi.
If you think about that, 110 psi compared to 11 psi, the discharge side of the compressor is so much higher than the suction side. Basically this difference in pressure wont matter to the flow of refrigerant and your system will work. Even if you were able to have some flow of refrigerant from the suction side to the evaporator there would be a check valve installed on the system that would make sure that you have the proper flow.
Try to think about the volume that the compressor has when both valves are closed and how much it can compress vs when the unloader forces it open and you have a large area/volume that cant really be compressed.
Gracias maestro super , muy professional y anos en HVAC y cosas que Uno no save. Thanks
Gracias!!! Espero que esto lo ayude!!!!
Very helpfull. Really. Thank you
Thank you so much! I'm glad it was helpful!
excellent explanation!
thank you
I'm glad you like the video and thank you so much for watching!
well done you, your explanation of this is awesome
Thank you!!!! I am glad you liked it!!!
Thank you sir. Very imformative resource. Worth subscribing video
Thank you!!!
just a superb explanation. Thank you again.
our unloader starts with 24vdc. after i press start on d compressor, what happen 2 d unloader? does it close n open on piston operation until it reach the high pressure and open up to the discharge pressure?
ronnie corpin Typically the compressor will start with that cylinder unloaded. Meaning that the piston will move but it would not do any compressing or work. It does that to keep the amp draw down and so that it is easier on the compressor motor. After a few seconds some manufacturers will remove the volts from the unloader so that it will load up and the valves will start to do some work, meaning the cylinder will actually be compressing refrigerant. You will notice the suction pressure is going to drop and discharge pressure is going to rise. When you do not need as much cooling, it will add the 24 V DC like in your case so it will stop the compression action. Most places/compressors use 24 V AC.
@@AirConAcademy thanks. our compressor run unloaded den a few seconds around 45secs, it trips. just loaded it with freon and still trips. haysss...
ronnie corpin are you saying the compressor runs for about 45 seconds? And then the compressor tripped and shuts off? Are you saying that you added refrigerant to the system? Or are you saying the pressures increase?
@@AirConAcademy the compressor stops running after 45secs...and we have a high temp discharge of 190 deg F. also an alarm saying high condenser temp after adding freon.
@@ronniec8370 You probably have nitrogen or other non condensables in the system. Make sure any liquid line solenoids are open manually
Nice explaination
Thank you very much! Thank you for your comment and I'm glad you enjoyed the video! Thank you for watching!
Very well explained
Thank you!!! I am glad you liked it!!!
@aircon please advise on Walk in Freezer maintenance in 55 degrees Celsius outside temperature
Wow! That is very hot! In my area we do not see temperature is that high! Near WASHINGTON DC. My suggestion is to make sure the condenser coil is clean, this way you get rid of as much heat as possible as easy as possible. Another thing I would suggest, and this is typically not done but it is some thing I have found that helps in very high temperatures, that is to run the liquid line and the suction line together and have them insulated. By doing this you are sub cooling the refrigerant even more before it gets to the metering device and you are keeping the refrigerant sub cool. The problem with this is that you will have to monitor the superheat at the compressor to make sure you are not overheating the compressor. As you run the liquid line and suction line together they need to be very well insulated to keep them away from the heat from the ambient air. One other thing I would check to make sure that I do have plenty of airflow on the condenser side so that I can remove as much heat as possible and keep the high side pressure low. I hope this helps and thank you for sending the question.
Sir, Could you please explain on below also, 1. What is High Suction Superheat? What will be the Problems? Solution?
2. Suction Temperature high and low limits and what problems it may cause?
3. Discharge Temperature limits and problems?
4. Reason for liquid or knocking?
Thanks alot Sir.
1.
High suction superheat is when you have the suction gas coming back to the compressor and it is too warm. If it is too warm, it is not going to call the compressor down like it should and the compressor might overheat and tripped on internal overload.
2. Just like I said, before if you have high temperature on the suction line. It will affect the compressor the valves because of the high superheat may overheat, specially the discharge valve and you could destroy those discharge valves. I'm not sure what you mean by love limits. But if the suction pressure is too low, your compression ratio will be high and that will work the compressor very hard then again, overheat or destroy a compressor.
3. If your temperature is high on the high side, you are going to damage the discharge valves up and they will leak and because of that you compressor is not going to move refrigerant like it should. We need to make sure the compressor stays full so it will last a long time.
3. Typically liquid came back to the compressor is going to give you the liquid knocking you were talking about. If you do not have superheat, then that will cause this problem you're talking about and kill a compressor. That's why you must have the proper amount of superheat.
I hope this answers your questions. You should take a look at my webpage, airconacademy.com, where I have some courses and explain all of this. Thank you for watching and for sending these messages over to me. Good luck out there!
@@AirConAcademy Many thanks Sir
Thnxs more sir wonderful explain
Thank you! I am glad you liked the video! And thank you for watching!
Good explanation
Thank you!!! I am glad you liked it!!!!
Very instructive,thank you very much,God bless
Thank you!!!
What time solenoid operate .
So compressor becomes unloaded
From where it get signals.
Is it operate by temprature setting
There are many different ways to energize and de-energize the solenoid. It can be done with a two or three stage thermostat. It can also be controlled by suction pressure or oil pressure. As the low decreases the suction pressure will drop and the oil pressure will also drop by monitoring this I have seen that they have controlled the loading and unloading of compressors. The easiest way is like I mentioned above by using a thermostat. As the load increases the thermostat would load another bank of cylinders doing more cooling, as the heat low drops it would unload the cylinder so that it is not doing that much work. And do less cooling. I hope this makes sense. I hope this explains it to you. Good luck.
@9:04 u r explaining that with loading and unloading suction and discharge pressure changes what I think is, consider an example, we have R404 in our system and require temp is 4 deg C , to achieve this we need suction pressure around 60psig , if heat load increase this evaporator's pressure goes down(i.e. suction pressure) and to maintain the pressure 60psig load on compressor increases and it will activate another bank of cylinder and when load decrease it will unload the bank. This is how loading and unloading works. AND you are explaining that the pressure difference changes with loading and unloading but we have to maintain pressure in evaporator to maintain constant Temp.
yes you want to maintain around 4C as the load increases the evaporator pressure or suction pressure should increase not drop, but when the compressor loads up that is when the suction pressure would drop to keep the pressure where it should be 60PSI so it can stay around 4C. As the load decreases or the room temperature drops it will automatically unload. and yes every time the cylinder loads up (or it is doing work) the pressure should drop and when it is NOT doing work the pressure will increase.
Wonderful sir.
Thank you!!!! I am glad you liked it!!!!
It is a Nice explain ❤️
Thank you so much! I'm glad you liked the video!
Good teacher
Thank you so much! I really appreciate your comment!
Thanks for sharing your explanation is very nice I appreciate it.
Thank you, and I’m having a webinar in a few minutes it is free so if you wish to join it please go ahead and join it
www.airconacademy-courses.com/event-details/hvac-troubleshooting-webinar
I appreciate your time and effort.
I have a question please yesterday I had question in my head that what would happen to a compressor if it runs on negative pressure for example ( low pressure switch incorrectly set) so that the compressor below atmospheric pressure runs.
many greetings from Germany
YES!!!! The low pressure switch is either not set properly or it is bypassed. make sure it is not happening because that will kill a compressor very easily!!! it will run with no refrigerant gas to cool it and it will fail