Hello Julio, thanks for another great video. I was wondering if it's possible to just change the powerhead when changing the freon. For example when converting a refridgerator system from R12 to a modern freon.. Or do I have to change the whole TXV? Thanks a lot
I am sorry to say that one of the things that changes is the size of the orifice. So it will be necessary to change the entire metering device/TXV I wish it was that easy, but the whole thing should be replaced. Thank you for watching!
Why do some txv valves have to be set manually? Does this valve open and close by itself, although I have seen that even on manually set valves there is a copper probe at the end of the evaporator Thanks & Regards
The TXV will adjust automatically to maintain proper superheat. The sensing bulb that is located at the outlet of the evaporator is sensing the temperature so that the valve can adjust and maintain proper superheat. That sensing bulb needs to be well insulated so it is not reading the air temperature, but the suction line temperature. When the valve is first installed, the technician should check the superheat and adjust the valve for the proper superheat. They do come adjusted from the manufacturer, but you must always check to see if there is adjusted for your unit. I hope this answers your question, thank you for watching!
Wow!. I cannot believe I do not have a video on wiring up an oil pressure switch! Thank you so much for your suggestion. I will make a note of it and I will take me some time because I do these on my free time!
Yes, all sensing bulb should be insulated so you can sense the actual temperature of the suction line. This is how the TXV figures out what the superheat is and if it needs to open or close. If it is not insulated it will read a warmer temperature and decrease the superheat, which could get liquid back to the compressor and destroy your compressor.
When the power had is rusted and doesn't allow diaphragm to push down, would you recommend only changing the power head? Or the whole txv? I've seen guys do both. Not sure if changing the diaphragm would let out a lot of freon once it's off. Heard a guy say it doesn't let a lot out, and wouldn't need to pull a vacuum after changing it because system will still have pressure.
If the sensing bulb is rusted and it does not have a good connection on to the suction line you can just clean it up and make sure it has good contact. The moving parts inside of the TXV will not get rusted because there is always refrigerant oil traveling with the refrigerant. I have changed the powerhead only on units that have lost the charge in the powerhead. I always recommend pumping the system down or recovering, I prefer to pump down, because it is faster and easier. According to the EPA you're not supposed to release refrigerant to the atmosphere. Not even a little bit. If someone you know is doing it they are taking a chance at being turned in and having to pay the new fine of $44,495 per day per occurrence. I remember before the EPA rulings came around, when we could release refrigerant to the atmosphere, I did something similar to what he is saying. I would pump the system down, including what was in the liquid line, I would pump it into the suction line and only leave between 5 to 10 pounds of pressure in the suction and liquid line. I would unscrew the old powerhead off and screw the new one in within five seconds, and with only 5 to 10 pounds of pressure in the system I would not release hardly any refrigerant and then there was no need to pull a vacuum or add refrigerant since I had pumped all of the refrigerant into the condenser. Now remember this is prior to 1994. I have been doing this since 1979. And back then they were none of these restrictions or regulations. Life was good! I make sure you don't get yourself into trouble. But that is how are used to do it back then.
I'm glad that you were questioning what I said. That is a good thing! Most of the material that I have seen says top or 45° from the bottom. I am not saying that the school was teaching you wrong. But this is what I have always seen. Like I tell everyone in my class. Don't believe anything I tell you. Go ahead and look it up! Get a book or instruction manual and see what it says. I always make sure that everyone in class does their own research. Ever since I was a kid I always researched what people tell me, just to make sure that I know the correct way of doing it. So I am glad that you were asking about the 90°!
I'm not too sure, what do you mean by moisture block. The only time I have seen moisture lock in a system is when there is moisture and as it goes through the orifice at the metering device the moisture freezes and it stops the flow of refrigerant. It does not happen often but it does happen. The best thing to do if you have this problem is to install a brand new filter dryer. I would install one on the liquid line and then a suction line filter dryer. I hope this answers your question, thank you for watching!
Something very important is that we need to replace parts with what the manufacturer says they should be. If the TXV is the correct one for the system it should not have any problem creating a pressure drop low enough to give us the -18°C for the cold room. We would still have superheat, because that is the purpose of the TXV to maintain constant superheat. So remember always use the replacement at the manufacturer suggests. I hope this helps and thank you for watching!
@@moustafaeltahan3206 if you want to calculate superheat, you will need to get the suction line pressure, convert the pressure to temperature. The temperature you get from the PT chart will be the evaporator temperature. Then you get the actual temperature from the line that is leaving the evaporator and you subtract the two. That will be your superheat for the evaporator. In other words, let's say that you have an air conditioning unit that uses refrigerant 22. You get the suction pressure. The suction pressure reads 68 psi G, when you convert that to temperature that converts to 40°. That means the evaporator is at 40°. When you get the temperature of the suction line as it is leaving the evaporator let's say you get 50° so you subtract the 40 from the 50 and you get 10° and that is your superheat. When you do the sub cooling, you do basically the same thing. You get the high side pressure, convert that to temperature. Then you get the temperature of the liquid line as it is leaving the condenser and you subtract the two temperatures. That is how you get super heat and that is how you get sub cooling. The manufacturer will tell you what the superheat should be and the manufacture could also tell you what the subcooling should be. Hope this helps and I hope this answers your question. Good luck and thank you for watching!
@@moustafaeltahan3206 IF we do not know what the superheat should be we ussualy use use 8 to 12 degrees of superheat and subcooling 15 to 20 subcooling. but it is best to find out from the manufacturer. thank you for watching!!!
Good evening sir, would you make a video on a important subject of liquid refrigerant mix with oil in evaporator ,condenser and compressor side. What's effects on refrigeration cycle in three positions . Specifically on effects Discharge superheat, suction superheat and subcooling. Kindly explain it important sir! Your video very helpful and clear subject 👌 👍
Thank U sir for this class on the TXV. Hearing from U is always nice.
Thank you so much! Hope you're having a good day.!
Thank you Julio once again for your teaching tc God bless. Always waiting for new videos. Tks
Thank you! Thank you for watching and thank you for asking God to bless me! It means a lot to me!
Hello Julio, thanks for another great video.
I was wondering if it's possible to just change the powerhead when changing the freon. For example when converting a refridgerator system from R12 to a modern freon..
Or do I have to change the whole TXV?
Thanks a lot
I am sorry to say that one of the things that changes is the size of the orifice. So it will be necessary to change the entire metering device/TXV I wish it was that easy, but the whole thing should be replaced. Thank you for watching!
Excellent job explaining the TXV operation.
Thank you!!!!
Superb explanation.sir 👍👍
Than yo so much!!! I appreciate your comment!!!
Why do some txv valves have to be set manually? Does this valve open and close by itself, although I have seen that even on manually set valves there is a copper probe at the end of the evaporator
Thanks & Regards
The TXV will adjust automatically to maintain proper superheat. The sensing bulb that is located at the outlet of the evaporator is sensing the temperature so that the valve can adjust and maintain proper superheat. That sensing bulb needs to be well insulated so it is not reading the air temperature, but the suction line temperature. When the valve is first installed, the technician should check the superheat and adjust the valve for the proper superheat. They do come adjusted from the manufacturer, but you must always check to see if there is adjusted for your unit. I hope this answers your question, thank you for watching!
Thanks very informative, sir plz make a vedio series on power wiring and control wiring of hvac.. Ahu, fcu, chiller, vav etc...
Good idea! Thank you. I'm trying to get back into making more videos.
thanks a lot sir🙂
Thank you for watching! And I'm glad you enjoyed the video!
very good video
Thank you!!!
Thank you me encantan tus videos
@@samortiz2890 Gracias!!!!
Hi sir greateengs
Can you do a video for how to wire up a an oilpressure switch in a compressor and also an explanation
It will be great full
Thanks
Wow!. I cannot believe I do not have a video on wiring up an oil pressure switch! Thank you so much for your suggestion. I will make a note of it and I will take me some time because I do these on my free time!
❤️🌹❤️🌹
Thank you!
Do we have to put insulation on Lennox sensing bulb?
Yes, all sensing bulb should be insulated so you can sense the actual temperature of the suction line. This is how the TXV figures out what the superheat is and if it needs to open or close. If it is not insulated it will read a warmer temperature and decrease the superheat, which could get liquid back to the compressor and destroy your compressor.
When the power had is rusted and doesn't allow diaphragm to push down, would you recommend only changing the power head? Or the whole txv? I've seen guys do both. Not sure if changing the diaphragm would let out a lot of freon once it's off. Heard a guy say it doesn't let a lot out, and wouldn't need to pull a vacuum after changing it because system will still have pressure.
If the sensing bulb is rusted and it does not have a good connection on to the suction line you can just clean it up and make sure it has good contact. The moving parts inside of the TXV will not get rusted because there is always refrigerant oil traveling with the refrigerant. I have changed the powerhead only on units that have lost the charge in the powerhead. I always recommend pumping the system down or recovering, I prefer to pump down, because it is faster and easier. According to the EPA you're not supposed to release refrigerant to the atmosphere. Not even a little bit. If someone you know is doing it they are taking a chance at being turned in and having to pay the new fine of $44,495 per day per occurrence. I remember before the EPA rulings came around, when we could release refrigerant to the atmosphere, I did something similar to what he is saying. I would pump the system down, including what was in the liquid line, I would pump it into the suction line and only leave between 5 to 10 pounds of pressure in the suction and liquid line. I would unscrew the old powerhead off and screw the new one in within five seconds, and with only 5 to 10 pounds of pressure in the system I would not release hardly any refrigerant and then there was no need to pull a vacuum or add refrigerant since I had pumped all of the refrigerant into the condenser. Now remember this is prior to 1994. I have been doing this since 1979. And back then they were none of these restrictions or regulations. Life was good! I make sure you don't get yourself into trouble. But that is how are used to do it back then.
In school they never said if the pipe is smaller than 7/8 to put it in top. It was always 90 degrees or 45 degrees..
I'm glad that you were questioning what I said. That is a good thing! Most of the material that I have seen says top or 45° from the bottom. I am not saying that the school was teaching you wrong. But this is what I have always seen. Like I tell everyone in my class. Don't believe anything I tell you. Go ahead and look it up! Get a book or instruction manual and see what it says. I always make sure that everyone in class does their own research. Ever since I was a kid I always researched what people tell me, just to make sure that I know the correct way of doing it. So I am glad that you were asking about the 90°!
Sir can you explain about moisture block in refrigerator how it happens and how to fix it
I'm not too sure, what do you mean by moisture block. The only time I have seen moisture lock in a system is when there is moisture and as it goes through the orifice at the metering device the moisture freezes and it stops the flow of refrigerant. It does not happen often but it does happen. The best thing to do if you have this problem is to install a brand new filter dryer. I would install one on the liquid line and then a suction line filter dryer. I hope this answers your question, thank you for watching!
@@AirConAcademy thanks sir 🙏
How to get target super heat for txv system for cold room if we need it to be -18 c
Something very important is that we need to replace parts with what the manufacturer says they should be. If the TXV is the correct one for the system it should not have any problem creating a pressure drop low enough to give us the -18°C for the cold room. We would still have superheat, because that is the purpose of the TXV to maintain constant superheat. So remember always use the replacement at the manufacturer suggests. I hope this helps and thank you for watching!
@@AirConAcademy I want to know how to calculate super heat or cool for my system and what number to compare with (target superheat)
@@moustafaeltahan3206 if you want to calculate superheat, you will need to get the suction line pressure, convert the pressure to temperature. The temperature you get from the PT chart will be the evaporator temperature. Then you get the actual temperature from the line that is leaving the evaporator and you subtract the two. That will be your superheat for the evaporator. In other words, let's say that you have an air conditioning unit that uses refrigerant 22. You get the suction pressure. The suction pressure reads 68 psi G, when you convert that to temperature that converts to 40°. That means the evaporator is at 40°. When you get the temperature of the suction line as it is leaving the evaporator let's say you get 50° so you subtract the 40 from the 50 and you get 10° and that is your superheat.
When you do the sub cooling, you do basically the same thing. You get the high side pressure, convert that to temperature. Then you get the temperature of the liquid line as it is leaving the condenser and you subtract the two temperatures. That is how you get super heat and that is how you get sub cooling. The manufacturer will tell you what the superheat should be and the manufacture could also tell you what the subcooling should be.
Hope this helps and I hope this answers your question. Good luck and thank you for watching!
@@AirConAcademy that was very helpful but the target super heat or subcool can be detected in another way if I can’t get manufacturer data ?
@@moustafaeltahan3206 IF we do not know what the superheat should be we ussualy use use 8 to 12 degrees of superheat and subcooling 15 to 20 subcooling. but it is best to find out from the manufacturer. thank you for watching!!!
Good evening sir, would you make a video on a important subject of liquid refrigerant mix with oil in evaporator ,condenser and compressor side. What's effects on refrigeration cycle in three positions . Specifically on effects Discharge superheat, suction superheat and subcooling. Kindly explain it important sir! Your video very helpful and clear subject 👌 👍
Thank you for your suggestion. I had not thought of that but I will see what I can do about that video. Thank you for the message!