tx valve

will smith_4

A txv is adjustable so you can set it up to maintain a desired amount of superheat. Compressor manufacturers will tell you how much superheat is required at the compressor for optimimum performance and protection. It's fairly standard to see a 10-15 degree superheat, though some want as much as 35. Once the system is stable and your superheat is set where you want it, you shouldn't have to touch it again. Make sure your bulb placement is correct, secure, and well insulated. Unless someone has played around with it, the txv is basically set and forget. I'd apply some leak lock at the stem cap on that leaker-

curiousity kills

tx valve

Is it normal for refrigerant pressure to come out the bottom of a tx when you remove the cap to adjust superheat

Jim Pompetti

Sometimes there is a set you can tighten at the point of ajustment,otherwise tighten cap to pervent leak lockleak may help

curiousity kills

HUH?I went to lossen the cap to adjust superheat and pressure and dripping refridgerant came out.Iended up pulling into sucback adjusting evacuating then opened system,My question was is this normal?

Techman

TXV

Hi! Was the TXV working properly, other than needing a slight adjustment?

will smith_4

txv

You should not expect a leak at a txv adjustment stem any more than you would expect a leak at any service valve. If the valve leaks and tightening the packing does not stop it, it has incurred damage (probably by being overheated when it was installed)-and should be replaced.

Eugene Silberstein 3

Definitely NOT Normal

This is definitely NOT normal.

One question, though. The TXV has a one-line job description, which is to maintain constant evaporator superheat. Prior to your attempting to adjust it, was the valve maintaining superheat? If so, why are we adjusting it?

If the TXV is not maintaining superheat, adjusting the spring pressure is not going to correct a mechanical problem with the valve.

curiousity kills

Actually the tx was union type and installed after brazing so it was not overheated.The valve was a Lennox and had a one to three ton rating.I was installing on a 2.5 ton. On first start up superheat was at 20 and I was trying to bring to 10.I was told to adjust because the tonnage flexablity of the valve.Please correct me if I am wrong.Thanks

Eugene Silberstein 3

Just be VERY Careful

When adjusting the TXV make certain that you turn the adjustment screw in SMALL increments at a time (0.5 to 1 turn), and be sure to allow the system to operate for at least 10 minutes between adjustments. Make certain that you repeat your superheat calculations before each adjustment.

Techman

Hay curiousity kills

On any "start-up " the superheat is going to out of bounds for awhile,then once the system is stabilized an accurate superheat can be taken and adjusted.Enjoy!

curiousity kills

Thanks for the responses but my original question was is it normal for pressure to come out when removing the cap

Techman

Just Courious

As The professor said -NO- .but I'm still courious about the superheat adjustment!

curiousity kills

well then why is it there if you dont touch it

will smith_4

if you get pressure when removing the cap

There is a leak in the valve-replace it.

Techman

Courious

It's there to be touched,BUT,BUT,BUT,from what to what?

steve_29

It's not surprising to find that the valve leaks... some more than others.

Make sure the nut is tightened so the leak is contained at the stem and not escaping.

Curiosity does kill... and in HVACR it's usually the compressor.

good luck

curiousity kills

thanks for the response

> A txv is adjustable so you can set it up to

> maintain a desired amount of superheat.

> Compressor manufacturers will tell you how much

> superheat is required at the compressor for

> optimimum performance and protection. It's fairly

> standard to see a 10-15 degree superheat, though

> some want as much as 35. Once the system is

> stable and your superheat is set where you want

> it, you shouldn't have to touch it again. Make

> sure your bulb placement is correct, secure, and

> well insulated. Unless someone has played around

> with it, the txv is basically set and forget. I'd

> apply some leak lock at the stem cap on that

> leaker-

Eugene Silberstein 3

So....

So txv manufacurers can sell a lot more valves when people adjust them when they shouldn't. The saddest part of the whole thing is that if a technicians does not know how to properly adjust a TXV they an successfully kill the compressor.

Just remember..... Small adjustments.... wait 15 minutes.... make superheat calculations...

No race..... take it slow.... nice and slow....