HVAC 089 fixed orifice piston closer look inside
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- เผยแพร่เมื่อ 3 ต.ค. 2024
- If you just got here I recommend going back to at least HVAC 052 HVAC 052 Measuring Wet Bulb, Dry Bulb and Humidity here • HVAC 052 Measuring Wet... and continue to HVAC 059 Example with fixed orifice.
Target superheat chart I made from the formula for the formula and chart
www.love2hvac....
Craig and Bryan both are great resources. here are some links below to help.
Craig with @acservicetechchannel does a great job explaining why the TXV is superior to the fixed orifice
• Thermostatic Expansion...
Target superheat from Craig
www.acservicet...
• Superheat Charging Cha...
Bryan Orr discusses target superheat @HVACS
• How to Find Target Sup...
HVACR school target superheat
hvacrschool.co...
My favorite HVAC App, we will be doing a video on this soon
measurequick.com/
articles on target superheat.
www.achrnews.c...
www.contractin...
You are definitely one of the best I’ve seen in this arena. Be blessed!
Thanks for the vid & the cutaway,👍🙏good stuff
So glad I found this. Great job on explanation and the cut away made it easier to understand. Thanks.
Great job on those cutaways Ty. If you could clean the one up with a deburr tool it would look sweet. Then you could see the contour of the line.
Picking up on many fine make/break/gotcha details from your series Ty, thank you. ;)
Wow..very nice details info I couldn't find anywhere else..I like your way of explaining small details. thumps up man👍👍👍
Great explanation of fixed orifice operation.
As always your awesome. Wish I could take your classes in person
Thank you
I think I see the progression of metering devices now. I referenced a paper in a comment on the cap tube video where I learned that capillary tube in refrigeration is more than an orifice but is, due to the change of state, an adapting refrigerant regulating device. But design specific as size and length is determined by trial an error in the design phase of the particular system. Not field adjustable. Creating a system excellent at its design point but not very adaptable.
Fixed orifice (piston) is field adjustably by a service tech changing the piston making off the shelf evaps, condensers and compressors adaptable to a variety of loads.
TXVs are adjustable orifices and mechanical superheat calculators that constantly adjust the orifice expanding the range of the load conditions a configuration of coils and compressors can successfully handle.
EEVs permit constant adjustment but via a microcontroller that can use more sensors and data along with pre-programmed operating profiles to cover even more operating loads/scenarios.
After readimg that paper I like the cap tube over a piston. However I still prefer a TXV or EXV
@@love2hvac I posted reply to that with another paper I found by the same author, more elaborate. I tried to put the website name but youtube made a link so it might have gotten dumped for that. THEORY AND FIELD PROBLEMS OF THE CAPILLARY TUBE By HENRY EHRENS is the name of the paper.
I dint see the link you posted but I found it and I posted it to your reply and to the description on the capillary video. Thank you for that. I love this kind of information and discussions!
@@love2hvac The paper cited in my comment above is different than the paper I posted about originally. Apparently a fuller version. Very interesting as it has quite a few troubleshooting scenarios. Even a description of an invention that used to be available for testing cap tube and compressor efficiency before adding refrigerant when changing a strainer.
Great video! Very clear explanation of operation.
Great and details video .Thank you sir
Thanks for this video Ty, I Appreciate it buddy
What you say at the end about measure quick. I have seen some technicians say, na I have my sman or whatever means of app they use. People don't realize that measure quick is way more then just calculate SH and SC. You can actually see the full performance of your system. Compression ratio is huge, and more.
Exactly! I will be getting to it soon. I am building the ground work first.
@@love2hvac I see 😊 and I'm following along. Hope you don't mind me using your techniques to teach others 😉.
Nicely done.
i think you just solved my problem with an RTU i've been working on, 2 pistons one txv removed still having liquid line restriction. and facepalm!! there is a screen there!
thank you
Incredible good video!!!!!!
Great video dude
My AC/Heat Pump appears to have a liquid line restriction/blockage in AC mode, No cooling, slight freezing, good subcool, really high superheat, airflow good, clean filter/evap, vents are all open, temp across filter/dryer within .2 degrees.. I plan on replacing the TXV and will check the filter screen once the system is opened (Thank You for that tidbit of knowledge).. My question is, (for information only and before I open the system), assuming that all the previously mentioned symptoms are correct, if I have no cooling in AC mode but in HeatPump mode the system works fine can I assume that the inline filter screen at the TXV connection is not clogged/restricted because the refrigerant appears to flow fine during heat mode.I am trying to decide if this would be a valid troubleshooting point to rule in/out a bad TXV. Good video and information. Thank You...
How do you recommend cleaning the sceen?
Nice
What is the name of that compression fitting? Not a flare. Everything else is brazed. One compression fitting... Hmmm
What if you have an older unit with no cone
So is it an either or situation where you either have a TXV or a piston or do people keep the piston when they add a TXV to system?
What size of piston should I use for a 4 ton 410 unit?
So at heat mode more refrigerant will be going to evaporator coil right
What happens if someone forgets to put it in?
What happens if it's put in backwards?
Can you pull the screen out? It looks permanent and not serviceable.
Some can come out others are permanently, you can replace the fitting or unsewat it and clean it then rebraze it
Correct amount of the refrigerant was added, but still coils freezing up after 1-3 hours ac running, (piston fixed orifice R22)
You think is a restriction?
Many thanks!
First I would check airflow.
It's the most overlooked part of Air conditioning.
Next I would look at refregerant restriction such as filter drier, kink in line, screen, or piston is too small.
Why does it have to match the compressor instead of the evaporator ?
The compressor is moving volume of refrigerant and changing the pressure from a low pressure to a high pressure. It cannot do that alone, it works with its teammate the metering device. The metering device restricts/meters a volume of refregerant and causes a restiction of hi pressure and low pressure.
The compressor needs the metering device to be able to build the high pressure and to create the low pressure differential. The low pressure is causing thebrefregersnt expansion to allow the refrigerant to boil.
The evaporators job is to make sure to boil all the refregerant to a superheated vapor to protect the compressor and the condening coil is designed to reject the heat the evaporator collected and the heat from the compressor.
Evaporator coils are some times much larger and sometimes smaller depending on how much dehumidification is needed. Some equient matches a 3 ton compressor to a "4" ton evaporator. The evaporator is nothing more than a heat exchanger. Using a larger evaporator allows for more superheated vapor and can boost the effecency. But the metering device would still need to be the 3 ton matching the refregerant volume of the compressor. Let's say you have a 4 ton evaporator coil and left the 4 ton metering device in on a 3 ton compressor. The larger opening would allow more refregerant threw and less pressure on the high side. It may not be able to build enough pressure on the high side to raise the saturation temperature high enough to reject the heat needed. Then it allows too much flow in on the evaporator causing the suction pressure to be to high meaning the suction saturated temp is too high and it wont be a low enough temperature to dehumidify a tech would add refregersnt to raise the head pressure but that ends up flooding the evaporator coil with refergerant that gets back to the compressor.
@@love2hvac Good deal follow up question.
Ive worked on a trane unit with a 7.5 ton compressor and a 5 ton metering device oem txv
Can you explain the benefits of this?
Do you have some model numbers?
What’s difference between chatleff and aeroquip?
Chatleff is a piston style metering device. Aeroquip are stainless steel hydraulic hoses and valves made by Eaton from what I can tell. Maybe a name not used in Australia for a refrigeration fitting.
Chatleff uses the teflon seal.
It's been a while since I've worked with the Aeroquip but I believe they use an o-ring inside similar to the preset line connections. I will have to look it up.
If the metering device was placed in backward, would the liquid line freeze?
On an AC, or HP in AC mode no.
On a heat pump in heat mode possibly.
Very good information 👍
Thank you!
I had a new evap coil installed and they forgot to install the orifice piston and the system was running for 2 months without the orifice installed. Can the compressor be damaged with this missing? Also when they discovered that the piston was missing they opened the line installed the piston and did not vacuum the system down and just added refrigerant.
I am so sorry to hear that.
Yes that will damage the system but it's difficult to prove and fight.
I really hate that people are out there doing that.
Can you explain exactly what gets damaged and why? The compressor now is making a buzzing sound and the evap coil sounds like rushing water.
Without a metering device the compressor will experience liquid floodback that washes oil away from the top bearings. Without lubrication on the top bearing and orbital scroll metal to metal wear occurs greatly reducing the life of the system.
Second, not pulling a good vacuum leaves moisture in the system. The moisture reacts with POE oil that turns into an acid that eats away at the evaporator coil, condensing coil, Cooper lines and compressor windings. When copper is eaten away from the system, it floats through the system until it plates on the hottest part of the compressor causing copper plating on the bearings until it's so thick the compressor can't start anymore.
Thank you for the great feed back.
If the piston screen clogged up, the psig on high side is going be high right.
Not necessarily
Yup had a few jobs recently with the piston installed the wrong way. Poor home owner had to eat the cost. Thought they are getting away with a cheap install guy and ended up with aggravation and more money.
I dont understand how those bad installers keep getting away with it.
@@love2hvac money talks (but the other way around 😂)
If the AC was exposed like furniture, cabinets, doors, and landscaping people would spend much more money on it.
@@love2hvac now I understand why they started with wall mount minis 😂
There are a lot of Hacks out here that don't have a clue about what they're doing and earning a good living.
Hi, do all the liquid line tube comes with the screen? Thanks
Some do some do not
you cant change the screen?
some you can, some you cannot very easily
@@love2hvac Sorry my english is not very good
@@love2hvac me refierro si se puede cambiar la red interna.
@@love2hvac If not easily, how would you go about?
If you have low SC and
👍🏻
I think I will invest in a set of digital probes. 🤔 ( maybe)😂😐
🍺🍺🍺🥃🥃🍇🏌🏻♀️
Stay safe.
Retired (werk'n)keyboard super tech. Wear your safety glasses.
Wait for my video on it.
What happens if you get rid of the piston
If you take it out you will have low subcooling and low superheated with poor cooling and sooner or later a dead compressor
@@love2hvac how would you know? Have you ever tried it?
@@CubanMofo I have seen systems where someone did the exact thing.
One was a new install and 4 where to replace dead compressors only to find someone at some time took the metering device out.
@@love2hvac weird they would get rid of it in a new install.
How did you clean the screen
rx11 or soaking it in 91% alcohol
Nice