Testing for noncondensables

[catmanacman]

There's other ways for non-condensables to get into a system other than a leak.

one way is maintenance tech not bleading the 410 from there hoses with the low loss fittings and putting a 60 inch hose full of liquid 410a in a r22 unit

[hvacrmedic]

You can run the test from the LL service port, no problem, even with the LL service valve wide open. Look for a SC reading on the static system with fan running of over 2°. You'll know when the liquid in the coil is at ambient temp when your temperature reading has stabilized. Any reading less than 2° SC could possibly be only instrument error, so don't scream noncondensables if your SC reading is above 0° but less than 2°. FWIW, if noncondensables are bad enough to cause noticable performance issues, then you'd really be looking for a static SC reading much higher than 2°. Convert your saturated temps to pressures, and do the math yourself. A 5 or 10 psi noncondensable partial pressure won't typically cause noticable symptoms. It would be best to get them out anyway, even at low amounts, but don't expect that in and of itself to eliminate the problems that you're trying to diagnose. HTH.

I've run this test many times. It works.

[doc havoc]

Thanks medic, that's exactly what I was looking for. I figured there had to be a way.

catman-speaking from experience? Based on the specific details you listed...

[kdean1]

P.s. I keep saying hemoglobin in refrigerant lines would take iron to transport oxygen. Imagine a surfactant lined purge system for non condensable gases?

Isn't hemoglobin blood? Why would that be in an HVAC system?

[SBKold]

Hey medic - this reminds me of the system you were helping me on this summer.

It was a txv indoors with a longish lineset all horizontal that would flash in liquid line close to indoor unit.

I was sure I had a liquid restriction but it ended up being noncondensibles and the txv had no liquid seal.

With the entire charge pumped into condensor it was about 25 psi partial or 10deg over ambiehnt.

I'm not sure how much static subcooling it would have shown with the long lines and all. Interesting.

[hvacrmedic]

Thanks medic, that's exactly what I was looking for. I figured there had to be a way.

catman-speaking from experience? Based on the specific details you listed...

Just a note, you'll want to verify a liquid seal at the LL service valve when using this method. Easiest way to do that is run it in cooling mode for a few minutes before testing.

[aircooled53]

It was called VACUUM back in my day, if you have P/T not measure accurate ,recover refrigerant, vacuum, check with micrometer and re-charge, NO more non-condensables

[doc havoc]

It was called VACUUM back in my day, if you have P/T not measure accurate ,recover refrigerant, vacuum, check with micrometer and re-charge, NO more non-condensables

I don't disagree with you, however, there are other things that can make P/T not measure accurate. So, detection and evidence of noncondensables prior to going through the recovery, evacuation and recharge process is somewhat desireable.

[Joseph'bidness]

It's not always practical to change the oil. (hermetic compressors with no drain plugs)

http://www.bestbuyheatingandaircondi...tegory_Code=C3

[Joseph'bidness]

I don't disagree with you, however, there are other things that can make P/T not measure accurate. So, detection and evidence of noncondensables prior to going through the recovery, evacuation and recharge process is somewhat desireable.

I don't change oil much... The dealer I have been doing work for is far more interested in just replacing stuff anyhow...

[SBKold]

How much oil do you really get out with a pump like that anyway. I'm assuming you cut the suction line and try to snake a tube in their? Never tried it but seems impossible on a scroll.

[Joseph'bidness]

How much oil do you really get out with a pump like that anyway. I'm assuming you cut the suction line and try to snake a tube in their? Never tried it but seems impossible on a scroll.

Not enough to fill the frying pan that's for sure... I haven't used either. Only changed oil once, and I dumped it out...

[Joseph'bidness]

There is no such thing as extra virgin olive oil either... Interesting fact picked up from Italy.. Anyways, I would think it can pump four to seven ounces per stroke. I would feed the tube through the "skinny" line...