Replacing HVAC Thermostatic Expansion Valve

[Tom M King]

Maybe time to change to a mini-split, and just leave that air handler up there.

[Tom M King]

Donate the old units to a Community College program that teaches HVAC. Get them to come take the old air handler out. You'll not only get a tax deduction, but they'll get some experience.

[Bill George]

TXVs rarely go bad, my guess its got a plugged inlet strainer or orifice. I would never attempt repairs in that close area, big danger of setting the whole place on fire. I am assuming the valve is brazed in. When I was teaching we would never send students out to job like that because of liability. He needs to hire a company to take it out and either repair or replace the AHU.

[Scott T Smith]

Maybe time to change to a mini-split, and just leave that air handler up there.

Very sage advice from Tom. I second it.

Mitsubishi makes some of the best mini-splits. Daiken is also pretty good.

[Robert LaPlaca]

TXVs rarely go bad, my guess its got a plugged inlet strainer or orifice. I would never attempt repairs in that close area, big danger of setting the whole place on fire. I am assuming the valve is brazed in. When I was teaching we would never send students out to job like that because of liability. He needs to hire a company to take it out and either repair or replace the AHU.

Bill, how does one repair a plugged inlet strainer or orifice?

Judging by the estimated quoted for the TXV repair, the repair was going to be quite labor intensive..

[Tom M King]

I hope Bill sees this, and answers.

The reason I was asking about how old the system was is because of my experience with one system here in a rental house we own. One system was not working. It's a 2012 Trane, so a 410a heat pump. They reused the old lines in the wall whenever they changed to this newer system in this 1974 house. The vapor line had a leak in the wall, so I figured I needed to change the lines to new ones even if I replaced the whole system.

I evacuated whatever was in the system, and while I had it open before pressure testing the new lines, I checked the inlet screen on the TXV. It couldn't have worked with as much gunk as was on the screen. Since the house was built in R22 times, and they had reused the old lines, the different types of oils in the different refrigerants had clogged up the screen. I cleaned the screen with carb cleaner and let it air out for a day before putting it back in, and vacuuming the new lines.

I wasn't confident that the system would even work, but it's still working fine now.

That's the reason I was asking about the age of the whole system. I don't have much experience with this stuff, like Bill does, but I don't think the screen in a whole new system like yours would be clogged unless there was some other failure in there somewhere like a compressor failing. Hopefully, Bill will add more insight.

The system has to be evacuated and the refrigerant recovered to take the inlet screen out, if it has one.

[Bill George]

Bill, how does one repair a plugged inlet strainer or orifice?

Judging by the estimated quoted for the TXV repair, the repair was going to be quite labor intensive..

On flared valves just pump down remove the inlet screen and clean. Brazed not so easy, just R&R complete valve. Plugged screens and the like are caused by dirt, copper shavings and improper soldering or failure to purge lines with Nitrogen when brazing. In short bad install procedures.

In the nearly 30 years of commercial service I replaced less than 10 TXVs.

When changing from R22 or R12 to 410a or 134a your suppose to flush out the old line sets. They sell kits to do so.

We were a full service company, nothing was subbed out all work was done by trained skilled techs and from a Union shop, Rarely did we have issues with anything. Made a lot of money going in after the others correcting the mistakes!! Felt sorry for the customers who needed to pay our bill for doing it right.

[George Yetka]

The cost for this work is almost all labor but im sure they are also marking up the material. It may not cost much more to replace the whole AHU. The lifespan of equipment nowadays isnt too good. You may be 2/3rds of the way there anyway.

My company does install only commercially, the refrigeration/startup/service is subbed out. In my case we are usually hit with a day charge at minimum. so I usually see things as lets just replace it and then we know its just an evacuation and charge.

[Tom M King]

The reason I started doing it here is the guy who did mine for over 30 years died, and it's been a flip of a coin as to what kind of service you get since then. The system I was talking about was probably installed by someone who did the least possible, so chance that the old lines were flushed out is not high percentage. One line was crimped, and a brazed line looked like they used the round end of a ball peen hammer to enlarge the one line.

So few people understand this stuff, that it's easy for a poor worker to get by with murder.

[Jerome Stanek]

What is the warranty on that unit. parts should be covered.