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-   -   Heat pump not working properly after hurricane power outage (http://www.diychatroom.com/f17/heat-pump-not-working-properly-after-hurricane-power-outage-161770/)

phuz 10-31-2012 07:12 PM

Heat pump not working properly after hurricane power outage
 
First post here on DIY, but after recently purchasing a home built in 1988, I am sure I will be on here more often.
The home came with a nice 16kW Generac generator and on Monday night before the power went out, we were experiencing some brownouts. The voltage was dipping pretty hard. It went out shortly after and the generator kicked in, but it does not power the heating system, so I don't think that affected it. When the power came back on today, I noticed that the Aux heat was running, which I expected because of the drastic temperature dip, but it has continued to cycle on/off to maintain temperature. I also have installed a TED5000 energy meter a few weeks ago, and I know when the heat pump used to operate before, the total house kW usage was around 8kW. Today I am seeing it operate around only 3.6kW and then after it fails to heat the home, it jumps to 17kW when the strip heaters kick in.
The inside circulation blower is functioning and the outside condenser fan is running, but am I safe to assume that the compressor is not running and I should check the contactor?
Thanks in advance.

carmon 10-31-2012 07:25 PM

Quote:

Originally Posted by phuz (Post 1042029)
First post here on DIY, but after recently purchasing a home built in 1988, I am sure I will be on here more often.
The home came with a nice 16kW Generac generator and on Monday night before the power went out, we were experiencing some brownouts. The voltage was dipping pretty hard. It went out shortly after and the generator kicked in, but it does not power the heating system, so I don't think that affected it. When the power came back on today, I noticed that the Aux heat was running, which I expected because of the drastic temperature dip, but it has continued to cycle on/off to maintain temperature. I also have installed a TED5000 energy meter a few weeks ago, and I know when the heat pump used to operate before, the total house kW usage was around 8kW. Today I am seeing it operate around only 3.6kW and then after it fails to heat the home, it jumps to 17kW when the strip heaters kick in.
The inside circulation blower is functioning and the outside condenser fan is running, but am I safe to assume that the compressor is not running and I should check the contactor?
Thanks in advance.

or call a contractor....

carmon 10-31-2012 07:26 PM

yes see if contactor pulled in....:thumbsup:

phuz 10-31-2012 07:31 PM

Thanks. I had a circuit board,transformer, and contactor all go at my old townhouse from a surge but I figured the board was running since the fan and aux het came on. I'll check the contactor and control voltage tomorrow.

beenthere 11-01-2012 04:26 AM

Quote:

Originally Posted by carmon (Post 1042042)
yes see if contactor pulled in....:thumbsup:

The contactor is probably pulling in since the outdoor fan is running.

Could be the capacitor got weak on the compressor side.

phuz 11-01-2012 05:56 AM

Quote:

Originally Posted by beenthere (Post 1042255)
The contactor is probably pulling in since the outdoor fan is running.

Could be the capacitor got weak on the compressor side.

Anyway to verify that without replacing it?

beenthere 11-01-2012 02:54 PM

With a meter that can read microfarads.

its a pretty cheap part to try.

phuz 11-01-2012 07:58 PM

Well, I was wrong...it is NOT the compressor.
I pulled the panel off and both compressor and condenser fan are running.
After a few minutes, there is frost on the larger line coming from the compressor and it is obviously very cold.
The smaller line is hot and can be touched for a few seconds before needing to pull away.

A friends father works in HVAC so he gave a few things to try.
I turned on the A/C for a few minutes, then turned it off for 15 minutes, then turned the heat back on, in case the reversing valve was stuck or not properly seated.
When the A/C was on, the air coming out of the vents was cool, but definitely not cold. When I turned the heat back on, the air was luke warm again with just the heat pump running.
I measured a duct temperature on the first floor to be 81F. After a bit, the electric strips kicked in again, and within a minute the duct temperature was at 108F and slowly increasing.

He thinks something with either the expansion valve, reversing valve, or low refrigerant.
The unit is a Carrier 38YZA and refrigerant is R410A.

Not sure where to go from here.

beenthere 11-01-2012 08:23 PM

Need a the to check it.

Missouri Bound 11-01-2012 08:34 PM

How cold was the room when you got that 81 deg. air? Heat pumps never put out a great amount of heat but they put out less when they are low on refrigerant. Only guages will tell you if that is the case. Your energy calculations are a bit confusing. A heat pump will use the same energy whether it's low on charge or not. Only when the resistance heat kicks in will it go up. It's time to pick up the phone and decide who is getting the check........:laughing:

phuz 11-01-2012 08:57 PM

Quote:

Originally Posted by Missouri Bound (Post 1042750)
How cold was the room when you got that 81 deg. air? Heat pumps never put out a great amount of heat but they put out less when they are low on refrigerant. Only guages will tell you if that is the case. Your energy calculations are a bit confusing. A heat pump will use the same energy whether it's low on charge or not. Only when the resistance heat kicks in will it go up. It's time to pick up the phone and decide who is getting the check........:laughing:

The room that was getting the 81F air was around 70F. I am not sure why the system would have lost refrigerant all of the sudden, but I am not convinced that is the problem. The energy monitor would show around 8kW anytime the heat pump was running prior to losing power on Monday. Now when the heat pump runs, it shows around 4kW and the house does not heat, so after a bit the electric strips kick in and it will jump to around 18-19kW. I know that a low refrigerant won't affect the current draw like that, but if one of the valves is failing to operate, would that prevent a load being put on the system, hence the reason I am only seeing half of the power consumption?

beenthere 11-01-2012 09:12 PM

Being low on charge does reducer current draw.

Missouri Bound 11-01-2012 09:32 PM

Quote:

Originally Posted by beenthere (Post 1042782)
Being low on charge does reducer current draw.

:eek:...by 1/2?

beenthere 11-02-2012 04:52 AM

Quote:

Originally Posted by Missouri Bound (Post 1042807)
:eek:...by 1/2?

That would depend on how low it is. The lower it is, the lower the amp draw since its not doing much work.


Until charge is checked. its all speculation.

phuz 11-02-2012 06:08 AM

Thanks guys. I'm having it checked ASAP anyway, so we'll see.


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