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MikeInCali 08-05-2010 06:00 PM

Testing a Heat Pump Heater in Summer
 
I'm buying a townhouse and it has a heat pump for heat and a separate AC unit for cooling. The home inspector said he turned on the heat and the compressor on the heat pump would not come on.

I called an HVAC guy who came over and told my realtor the compressor will not come on by design because it senses the outside temp as being hot, and that it is fine. I was not able to be there so I havent spoken to him directly yet.

Can anyone confirm this is a common design? I want to trust what he said but I'm just worried that come winter the heat won't work and I'll have to shell out a ton of cash for a new heater. I don't know why a home inspector wouldnt know this.

Thanks for your responses,

Mike

Marty S. 08-05-2010 07:27 PM

Heat pumps cool and heat so the compressor should run. I've never seen any temp sensor that locks out the reversing valve.

hennyh 08-05-2010 08:42 PM

Quote:

Originally Posted by MikeInCali (Post 481038)
I'm buying a townhouse and it has a heat pump for heat and a separate AC unit for cooling.
Mike

I'm confused. What do you mean it has heat pump for heat and a seperate AC unit for cooling. A heat pump performs both heating and cooling functions.

Is it peforming fine in the cooling function? If you toggle the reversing valve then it should heat.

I've never heard of lock out features to prevent heating in the summer unless it's simply thermostat programming with OD sensors which can be overridden for testing??

MikeInCali 08-05-2010 09:30 PM

Thanks for your responses. Sorry for the confusion, I'm still learning about these. It is indeed one system. What I thought was separate is the air handler which is in the closet, while the system itself is on the roof.

Anyway, I spoke to the technician and he said that the high head pressure sensor would trip because the outside air is so hot, keeping the heat from coming on. He can't seem to tell me definatively if the heat side works or not:mad:

The compressor works because the A/C is working.

We called back the house inspector who isnt buying it. He recommended his HVAC guy who isnt buying it either and is coming to take a look tomorrow.

beenthere 08-05-2010 10:21 PM

Some heat pumps have high pressure switches. Some don't.

Hope no one is trying to run it if its above 80 outside. Even below 80, It shouldn't be allowed to run for more then a minute or 2

Damage can occur.

MikeInCali 08-05-2010 10:49 PM

Thanks, yeah thats what the tech said. So is there any way to definatively tell if the heat side works? I don't want to wait until November to find out I need a new heat pump.

beenthere 08-05-2010 10:56 PM

When I check a new install or swap out in the summer.
I pull the disconnect for the outside unit. Then turn the stat to heat. Go outside and put the disconnect back in so the unit can run. And if it runs in heat mode. I pull the disconnect pretty quick. Then turn the stat back to cool. Put the disconnect back in. And call it good.

Thats the easy safe way.

veesubotee 08-06-2010 06:50 AM

Just curious, does replacing the disconnect, while a call for heat or cool is active, cause arcing/pitting of the contacts?

beenthere 08-06-2010 07:31 AM

On a pull disconnect. You get an arc on it. But it doesn't cause any arcing at the units contactor. Since the contactor is closed.

Of course, if the 5 minute delay time hasn't expired yet. There is no arcing at the contactor when you put it in. And will be at the contactor, as it normally is.

hennyh 08-06-2010 11:51 AM

Quote:

Originally Posted by MikeInCali (Post 481198)
Thanks, yeah thats what the tech said. So is there any way to definatively tell if the heat side works? I don't want to wait until November to find out I need a new heat pump.

If it's running just fine in cooling mode, the coils looks clean, amperages and pressures check out, then the chance it will perform just fine in heating mode is quite high.

The tech. could jumper the reversing valve and listen to make sure it moves over.


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