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billyex99
11-02-2009, 08:21 PM
Hi all, Purchased a bryant evolution hybrid system this June. 16 seer 2 stage hp with a 95% furnace for northern Indiana. Worked great this summer for AC. But twice now in a month in the heat mode it has made a loud squeal sound followed by the fan stopping and then a few moments later it sounds like it is trying to start up again but doesn't. The first time I looked at the TS and it had switched to BU heat source. The second time I just switched it to furnace only. Both times outside temp was mid 40s. Called rep and he said it would have to do it more often for them to diagnose. Don't like getting woke up at 4:30 as the HP is right outside bedroom window. Any ideas?
WhoIsThat?
11-02-2009, 08:33 PM
it has made a loud squeal sound followed by the fan stopping
Does it have a belt drive for the fan?
naysayer
11-02-2009, 10:06 PM
Sounds like it is going into defrost. The loud squeal is probably the pressure change from the reversing valve switching into defrost. Condenser fan off and emergency heat on both jive with defrost. Sounds normal.
beenthere
11-03-2009, 06:19 AM
Sounds like it is going into defrost. The loud squeal is probably the pressure change from the reversing valve switching into defrost. Condenser fan off and emergency heat on both jive with defrost. Sounds normal.

Yep.

Some heat pumps have a quiet switch mode.
Ask your installer if your has that option.
WhoIsThat?
11-03-2009, 09:13 AM
Some heat pumps have a quiet switch mode.
So the squeal is eliminated by switching more slowly?
gary_g
11-03-2009, 10:41 AM
Sounds like it is going into defrost. The loud squeal is probably the pressure change from the reversing valve switching into defrost. Condenser fan off and emergency heat on both jive with defrost. Sounds normal.

Mine sounds like a "moose groan" when it goes into defrost.

I've never actually heard a moose groan, but if I did, that would be the sound that it would make :)
WhoIsThat?
11-03-2009, 11:09 AM
Mine sounds like a "moose groan" when it goes into defrost.

I've never actually heard a moose groan, but if I did, that would be the sound that it would make :)
So it's a design defect that only shows up on some units under some conditions?
beenthere
11-03-2009, 12:01 PM
So the squeal is eliminated by switching more slowly?
No, the compressor shuts off, until the RV switches, and the pressures are closer to equalized.
beenthere
11-03-2009, 12:02 PM
[QUOTE=gary_g;4929752]Mine sounds like a "moose groan" when it goes into defrost.

QUOTE]

Often caused by an improper charge.
gary_g
11-03-2009, 12:07 PM
[QUOTE=gary_g;4929752]Mine sounds like a "moose groan" when it goes into defrost.

QUOTE]

Often caused by an improper charge.

Superheat and subcooling in spec.
beenthere
11-03-2009, 12:14 PM
[QUOTE=beenthere;4930392]

Superheat and subcooling in spec.

Air flow in CFM should be verified.

SH and SC, in spec, or exactly on what is called for.
gary_g
11-03-2009, 12:53 PM
[QUOTE=gary_g;4930442]

Air flow in CFM should be verified.

SH and SC, in spec, or exactly on what is called for.

I never checked air flow, but my opinion is that I'm good with flow.

My split temps are close with Goodman's published data. A little low on heating split temp, but that may be because (as you pointed out before) they could base their temps on lower than normal flow, 355 cfm per ton instead of 400 cfm per ton for a 3-ton.

Goodman Specs for TXV-equipped evap coil:
Subcooling: 5 to 9F. Measured 6F.
Superheat: 7 to 9F. Measured 7F.
beenthere
11-03-2009, 03:23 PM
[QUOTE=beenthere;4930472]

I never checked air flow, but my opinion is that I'm good with flow.

Kind of like when a tech says air flow is good. Means they didn't measure it, and have no idea what it actually is.

My split temps are close with Goodman's published data. A little low on heating split temp, but that may be because (as you pointed out before) they could base their temps on lower than normal flow, 355 cfm per ton instead of 400 cfm per ton for a 3-ton.

Goodman Specs for TXV-equipped evap coil:
Subcooling: 5 to 9F. Measured 6F.
Superheat: 7 to 9F. Measured 7F.

While those reading are "within spec", they barely make it. And there is a good chance, that the noise you hear, is because the charge probably isn't quiet right. Close but no cigar.

While your blower may be set to a speed that they thought gave you 400 CFM per ton. It probably isn't.

Had RV's make noise because of an overcharge, and because of an undercharge.

Most of the time. When they are loud, the charge is incorrect.