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Old 05-01-2012, 02:17 AM   #1
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Refrigerant problem


Two story with air handler in the attic. Lineset goes underground from the parking lot outside of the back patio ( condo type deal) and then up and into the evaporator.

gauges state 75 psi (aproximately 45f) on the return low vapor. Check the suction line at the evap, nice and cold and sweating.

Check it at the condenser and it's ambient temp, 80-ish degrees. No sweating, not cold, not nothing.

Pressures seem to be okay at 75/200 but the supply air at the registers is 80+f.

Not a restriction but what?

Ps, the lineset does not go above the evap but rather under the air handler and then up into the evap.

Oil trap?

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Old 05-01-2012, 05:24 AM   #2
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Refrigerant problem


How high is the evap above the condenser? You may have 2 strikes against you. How long is the run underground?

If the evap is 20 foot above the condenser, then the liquid line pressure at the evap will be 10 PSIG lower then at the condenser if its an R22 unit.

The 75PSIG for R22 gives you a sat of 44, so with an 80 vapor line, its over heating the compressor. What was your SC? And what was he actual outdoor temp.

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Old 05-01-2012, 10:50 AM   #3
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Refrigerant problem


Looks like you have a blocked suction line.
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Old 05-01-2012, 11:45 AM   #4
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How high is the evap above the condenser? You may have 2 strikes against you. How long is the run underground?

If the evap is 20 foot above the condenser, then the liquid line pressure at the evap will be 10 PSIG lower then at the condenser if its an R22 unit.

The 75PSIG for R22 gives you a sat of 44, so with an 80 vapor line, its over heating the compressor. What was your SC? And what was he actual outdoor temp.
First things first, I installed a condenser for this guy that he himself had purchased maybe last year. It was all working fine until recently and even before the new condenser, for the past 30 years or so since the home was built, I'd assume, as the only lineset is the one underground.

I didn't get to the home until almost 9 last night, I was not going to really get into it so can't tell you what any numbers were except for what the gauges were reading.

Can't be a restriction, gauges were not pulling down. Yes, it showed 75psig (44f sat) but again, warm at the condenser.

Lineset travels about 15', not sure how deep it is buried, under the back patio and then up and into the wall, into the second story attic and then about 25' across the attic to under the air handler and comes up and into the evap.

I was going to pump it down and use nitrogen and clear the lines and see what happens.

Evap is probably 20' above the condenser. I'll take pics today.
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Old 05-01-2012, 04:22 PM   #5
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Refrigerant problem


When last year did you install it? m ay have been late enough in your cooling season, that he didn't notice it wasn't cooling right.

Your describing a 60 foot line set. The 15 foot of underground is probably giving you a little extra Sc, which isn't actually a good thing in all cases. The 20 foot vertical is giving you a 10 PSIG pressure drop so that at best your at 190 PSIG when it reaches the condenser. but probably close to 180 given the line length and throwing in a few 90 ells.

So using a shot in the dark, you got a slightly low on charge unit(leak maybe), and if its a TXV, the TXV is opening wide up trying to maintain SH.
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Old 05-01-2012, 08:58 PM   #6
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Refrigerant problem


As much as I do agree that the lineset being underground and having an approximate 15' of lift plus another 35'-40' of length in the attic to get to the evap is a concern, that is not the problem. I checked the temperature of the vapor line at the evap and it was 79.? That fiasco completely took me for a loop, wondering how in the heck could the air be coming out at 80 degrees when my gauges are showing the sat to be 44f? I guess the question is, why are my gauges saying it's 44-55f? Yellow Jacket anologue.



Into the concrete and underground.


Length of the patio. Just to the left of the satellite dish and on the other sisde of the fence is the where the condenser is located. Approximately 14'-15'.


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Old 05-01-2012, 09:04 PM   #7
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Under the air handler.






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Old 05-01-2012, 09:04 PM   #8
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Refrigerant problem


Low on charge.

Bet if you recover it, and weigh it. then measure the line set. You'll find you short on charge. Probably have flash in the liquid line, and are feeding liquid and vapor into the evap. Which will give you a vapor pressure that is misleading.
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Old 05-01-2012, 09:07 PM   #9
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I added. The head pressure went up and the air temp as well.

I pumped it down, nitrogen pressure tested as did I when I first installed the condenser, and vacuumed. No leaks whatsoever. As a matter of fact when I first went there last night I had to recover a little bit as both the pressures were abnormally high.
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Old 05-01-2012, 09:10 PM   #10
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Refrigerant problem


Next time there. Do a frost test. Disable the blower, and see how the evap coil frost up. Could have a restricted distributor line.
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Old 05-01-2012, 09:12 PM   #11
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Refrigerant problem


After vacuum and release.

Vapor line.


Liquid line.


Attic line temps.
Vapor.


Liquid.
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Old 05-01-2012, 09:15 PM   #12
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Also. check to make sue your not drawing in attic air. usually if you are, the head goes up pretty high also.
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Old 05-01-2012, 09:16 PM   #13
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Next time there. Do a frost test. Disable the blower, and see how the evap coil frost up. Could have a restricted distributor line.
What exactly will I be looking for, if the entire thing freezes up or only part of it? How should it freeze up?

But something like that is definitely the issue. I'm going for a new txv and am going to at the very least raise the lineset to above the air handler/evap and see what that does. The txv was not opening and closing, not on my gauges. It was acting like a piston, a slightly restricted one at that. So perhaps the other guy was right..? I'm going back to do the job tomorrow morning.
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Old 05-01-2012, 09:20 PM   #14
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Refrigerant problem


I checked for return leaks, nothing. Clean coil.


Txv.
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Old 05-01-2012, 09:29 PM   #15
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Refrigerant problem


due to long refrigerant line runs have you ensured you have the correct size liquid line to ensure enough liquid to coil...also is suction line large enough... the increased velocities in an undersized suction line reduce capacity...

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