Should You Replace a Bad TXV with a Piston? & TXV Diagnosis!

[@JohnKirchner-oi1oz]

As usual, Craig covers all the details which matter for a proper installation. I have learned more from him than all my books and instructors combined. Thank you Craig for showing and sharing with us the details that we should all be following so we can give the customer the best install. I hope to meet you someday to personally thank you for making me a better technician

[@edlauren9434]

Love your videos! Thank you for your great teaching work! Here is my story piston vs. TXV. Have a Subway restaurant customer. They've got 2 pretty old R-22 5-ton split systems. Last summer I've installed TXV on one system. This customer don't change air filters on a regular basis. These filters get clogged pretty fast and in the system with a piston clogged air filter will result in no evaporation at the evaporator coil and a lot of liquid refrigerant returning to the condenser flooding/damaging the compressor. So, a month ago (August 2024), the compressor on the system with the piston started to run loud, to pull ~ 19 Amps on run and to kick Amps on start up to 58 Amps, tripping the breaker. Pretty much it's a classic wear-and-tear compressor's story. I had to replace that condensing unit. The system with TXV is still running pretty happy.

[@lukaszs4458]

I had this issue with txv in my trane system. I measured 46 deegrees of superheat and only 1/3 of evap coil was cold and frozen because the suction pressure was 80psi. Found almost completly cloged strainer in the txv outlet. I replaced the txv myself with the new one, and now the system works like new. I have 23 degrees delta T. Super super grait explain Craig. Thank you

[@usahoangsatruongsa]

When I have to replace an evaporator coil because the old one was leaking refrigerant I always choose a new one with piston. HVAC tech for over 20 years.

[@martinheatingcoolingmartin4693]

This is excellent information. I suck at diagnosing TXVs! I will be buying your literature also.

[@972958]

I had this exact issue and i decided to switch out the txv. Glad i made the right choice

[@USA-GreedyMenOfNoIntegrity]

Many times a shrader core can be installed in external equalizer port.

[@horsth9566]

Clearly and thoroughly explained. Excellent presentation. Thank you Craig!

[@johnnylowery5727]

This is the first that I've ever heard about not pumping down a scroll compressor. I work on commercial refrigeration systems primarily. These systems shut down with a pump down constantly. The majority are scroll compressors. If scrolls weren't intended to be pumped down, these would not be designed to do so.

[@chrisdeanndavison3626]

13:05 Generally, if I replace a TXV with a piston, it is simply to get the customer cool as quickly as possible. I have a whole stash of different pistons I keep in my van. I also have several pages of tonnage vs piston size charts to help with a proper match. In a matter of an hour or two I can have the unit cooling again instead of waiting a few days for the TXV to get shipped. I usually discuss the two options with the home owner and they always choose the piston.

[@watermanone7567]

Do you know where to get those charts? Thanks

[@chrisdeanndavison3626]

@@watermanone7567 They are just piston sizing charts I've saved from "new" units I've installed years ago. If you could find installation manuals for older units, they would likely give the recommended piston sizing.

[@broncheemims8493]

As usual, I like your video. Quite informative

[@johncote2776]

I've replaced pistons with TXVs with good success

[@DJV94022]

Its exactly like converting a automatic to manual put in this case manual to automatic😂

[@chrisspanyer1525]

Great video. Would love to hear your thoughts on which shrader valve core to use with which refrigerant best brand. Thanks

[@mosessanga6029]

That is what i wanted to know thanks you for sharing this video big thanks to AC Service Tech LLC

[@zx001961]

Very good teacher Thank you

[@acservicetechchannel]

Thank you! 😃

[@jessienascar8778]

Hey boss, you have a video about shuting off the vapor line and liquid line and vacuum the refrigerant from the one area you said lol? Also about the long tall compressor and why not to take out all the refrigerant from it because it will short?

[@zekenzy6486]

Great video. Thank you for sharing. Have a nice weekend

[@solankibharat8963]

Nice information good knowledge in work ac unit

[@richlikeg3722]

You can pump down a scroll compressor. Never seen one short before, maybe bypassed?

[@francom6230]

I've seen guys pump scrolls down until they sound horrible.. I'll ask my friend.. he's been doing ac for 40yrs

[@Owen-xw8cs]

@@richlikeg3722 you can safely pump them down. Some low temp units that pump down every off cycle have scrolls. This is silly

[@Succeedlikeyoubreathe]

Exactly what I thought. I have found that you can’t get to 500 microns when vacuuming through a scroll. Never have I seen someone close the valves. Or reuse 410a after recovering just the line charge. How do you know which blend migrated to the line set. Also who knows why sludge is in the 410a that caused the restriction.

[@watermanone7567]

Nice video, is there a chart that sizes the pistons with the unit size if it is necessary to change to a piston? IE: A three-ton unit would take a certain size piston?

[@philiph1234]

Another very good video. Thank you, Craig. for more versatility, what’s your opinion of using Sweat TXV’s and just removing the piston but leaving it housing in place, then sweating in a TXV? What’s your opinion of sweating a TXV just exterior to the air handler? I’ve purchased your books to show support. Thank you. Do you also have a PayPal account to make donations to?

[@deanmartin1966]

Great video. Thanks for sharing.

[@philiph1234]

What screen do you recommend before the txv? Many systems have a filter/ drier in the condensing unit. What's your thoughts of adding an additional filter/ drier (instead of screen) just before the air handler/ evaporator ?

[@erics9213]

I just bought a 7 CFM NAVAC vacuum pump. Should I stay w/NAVAC vacuum pump oil or could I use JB, YJ or some other vacuum pump oil with no consequences?

[@ChrisHVACguy]

about pumping down a scroll, when you say it would be "shorting out inside", are you referring to bypassing internally? or shorting out the windings? am I wrong by pumping it down as much as it will, close valves and recover what's left?

[@Owen-xw8cs]

It’s bs

[@sheldon8115]

Good job on that video.

[@shifter8207]

When you’re picking a txv to replace a piston do you pick a bleed port txv or non bleed port. Depending on the condensing unit most of them don’t come with start caps or hard start kits does it matter which txv you choose ?

[@Owen-xw8cs]

@@shifter8207 if it has a scroll it will start. If it has a recip it needs a start cap or a bleed valve with a time delay. Also some units need a bleed valve to prevent annoying harmonics after shutdown

[@davem3789]

On my R22 system I have very high superheat (50F) and slightly high subcooling (11.5F). I put my TXV bulb in warm water and for a few minutes it got the superheat down to around 20F and iit started rising again. Seems I have a TXV issue. Mine is all sweated in. Guess I should get a torch set and try to replace.

[@USA-GreedyMenOfNoIntegrity]

Or you could temporarily put your bulb on top of an old school incandescent lightbulb to heat it up like I did for a customer one time.

[@threestans9096]

@@USA-GreedyMenOfNoIntegrityyour own body heat can do that cant it? someone want to explain this in autistic detail to a newbie? Id highly appreciate it. Like why the sh would be that high and what the bulb heating is telling you guys ?

[@DoctorSleep_0]

​@@threestans9096The bulb has its own charge of refrigerant independent of the system. The bulb is mounted to the suction line. This way, when the suction line is warm because it's picking up too much sh and therefore not allowing enough refrigerant to pass through, the refrigerant in the bulb boils off and creates a higher pressure inside. This is the opening force on the TXV. That pressure depresses the diaphragm in the TXV and opens the valve further so that more refrigerant can then pass through the TXV and enter the evaporator to lower the superheat.

[@davem3789]

@@USA-GreedyMenOfNoIntegrity Just tried that and the first 15 min everything looked pretty good. Then superheat went way up again. My unit is 23 years old. Not sure at this point.

[@attackthedefault8042]

Don't forget to check for and temp drop across the drier! Just this past week I had a unit running 45° superheat and low saturation ended up being the drier couldn't believe it since I could only measure 1.5° drop but after I changed it the system went back to normal!

[@217angelito]

Believe or not i pass my state test just watching all his videos i study so little but i watch most of the videos

[@Owen-xw8cs]

It’s better to check the sensing bulb with ice water if your line temp was 70.

[@JavierMartinez-cy7qs]

Greetings. Thanks.

[@lethalaccuracy155]

Hey guys, I’m a plumber who does a lot of HVAC work. I live in Australia. Is it worth getting your books and cue cards where I am. I know a lot would be working in Fahrenheit where as we work in Celsius. But I’m just wondering if it’s going to still be of value. Thank you!

[@acservicetechchannel]

The mini split book certainly would work. the quick reference cards use celcius and farenheight. The refrig charging book would be good if you can do tge conversions for the examples, however we dont go over pascals or bar. Are you mainly working in Pascals?

[@lethalaccuracy155]

@@acservicetechchannel thanks for the reply, I really appreciate it! Yeah we mainly work in kPa. It shouldn’t be too hard to convert though would it? We use 1/2”, 3/4” and all that as well which isn’t the usually system we use to measure. Only seems to be for the pipe sizing haha

[@georgekolos5255]

Pump down to around 10psi. Get ready to the rest quickly. Put in new TXV or piston on the fly and you dont have to pull new vacuum, change drier / etc.! If your good, you can also braze up leaks while there is still a slight + pressure in the system. Ans wala! Again, dont have to pull a new vaccum/ etc!

[@salehhamid]

What is your thought if I peplace a capillary tube on a mini-split with a TXV ? Will it work more efficiantly ?? Thanks

[@raidone7413]

I thought all minisplits had txvs. How old is it? And is it capillary tubes or are those distribution tubes to the evap that got confused with cap tubes?

[@acservicetechchannel]

Mini splits either have cap tubing or an eev mounted in the outdoor unit. The lesser expensive and/or lower sized units have capillary tubing. I dont know of any minisplit with a txv. We wrote a whole book on minisplits from the refrig side to the electrical side. Make sure to check that out at acservicetech.com thanks!

[@grigorshukerski8822]

I can custom make you an EEV with control module for your unit if interested

[@calex9398]

Very nice my friend

[@ziggy6645]

I hate a txv. Nothing but problems on a pos trane. Finally replaced with a piston, problem solved. Cools better than ever.

[@seek3n]

Same for me but only on carrier😂

[@losgallosmx]

Tks man

[@pelon542]

a piston is not as efficient as a txv but a piston will NEVER fail if properly installed

[@jamese9888]

AND thats the reason I installed my 2 systems with a piston. Ive seen units running with piston and normal maintenance get replaced 20-30 yrs later still working but not very efficient. And Ive seen units have issue with a TXV getting replace several times over several years. Each time having to pump down and recharge. I dont want to do all that. The efficiency cost savings isnt worth it when one of those fragile TXV's stop working. I dont think most TXV's will last 20 yrs of daily use, while a piston is just a small hole and no moving parts.

[@Owen-xw8cs]

No they can fail just not as often

[@pelon542]

@@Owen-xw8cs how can they fail when there is absolutely nothing to it?

[@Owen-xw8cs]

@@pelon542they can get worn from sliding into position yes even brass or they stick sometimes and they can definitely clog up as well

[@Owen-xw8cs]

@@pelon542 still not nearly as likely as txv issues obviously

[@davem4457]

I noticed some of those TXVs are adjustable, do you ever try to adjust them or do you just leave them at there factory setting?

[@Owen-xw8cs]

@@davem4457 depends

[@anthonylosego]

Wait "and the vapor line service valve" 4:56 . Would you not want that open to pump down?

[@anthonylosego]

Oh, and recover, sorry, you go so fast! Hard to keep up! lol

[@seanphillips1828]

He was talking about recovering the lineset in that part of the video for condensers that cannot be pumped down

[@1Subcooling]

Where the heck was this gentleman in HVAC school??

[@shifter8207]

I thought you picked piston sizing on what condensing unit you have ?

[@lillyinthefield2787]

You have different Playlist??? Start with fundamentals or the basics ??? Wish you had a Playlist from beginners to pro ...in order 😢😢

[@Succeedlikeyoubreathe]

Wait you didn’t remove all the near azeotropic blend refrigerant. How do you know which blend you released and what the blend is while in the condenser. They saturate at different temps so the refrigerant in the lines may be blended differently than that in the condenser. It’s always a great idea to remove all the 410a and put fresh liquid back in to have the accurate azeotropic blend. Also what if the 410a Is dirty with sludge and caused the restriction. Always use fresh charge

[@georgekolos5255]

Bunch of BS such is proven to be these days of having to pull entire charge and charge from scratch with new refrigerant if you had a leak and lost majority of charge. These days also. Your never sure that there is even just one refrigerant in a system! Talking about people that top off one gas with another similar one!

[@edubracer15]

All Hail the TXV!!

[@matthosseini4194]

❤❤❤❤thanks 👏👏

[@lillyinthefield2787]

Is there. A ONLINE CLASS OR COURSE YOU OFFER TO LEARN THE HVAC TRADE ?? AS A BEGINNINER ???OR IS YOUR BOOK ALL I NEED ???

[@رافدرائع]

Why don't you use a valve before changing manually with a gradation according to the cold?

[@DayClanTribe]

I often wonder if it's ever worth the money and effort to add a accumulator to a piston system just as cheap insurance? Can someone tell me why not?

[@henrydang1644]

Hello everyone! Can everyone please help me some advice for the issue I just got, The issue is “ the high side up to 490 psig and low side is about 110 with vast 30 F degrees “ so I changed the TXV inside the air handler and the result come out with the high side 320 psig low side is 115 psig and vast around 35 F degrees, subcooling up to 18 and superheat up to 24 . So any advice please

[@user-xk5so7wb2t]

AWESOME VIDEO.. BUT CHANGING A TXV WITH THAT BADLY RUSTED COIL IS PAST FOOLISH. JUST REPLACE EVAP/TXV UNIT & GET THEM 10YR WARR. NOT A 1-5YR W/ TXV ALONE.

[@Owen-xw8cs]

A piston has more capacity than a txv under a higher load… anytime the superheat is less than the txv it has more capacity up to completely flooded…

[@Owen-xw8cs]

Basically exactly backwards. The txv is better under low load

[@johngatsby1473]

TXV's are trash and prone to failure. The increase in efficiency isnt worth the cost of repairing/Replacing the stupid thing down the road. Get a piston and be done with it.