Heat Pump Inspection

[David A. Andersen]

There is nothing an HI can determine about the defrost cycle unless you just happen to be lucky and catch the unit in defrost or unless the unit has a large amount of ice build up on the condenser fins indicating the defrost is not performing as intended.

CB,
For your personal reference only, diagnosis of the defrost system can be performed several ways depending on how intensive you want to get.

1. You can accelerate the time clock on the defrost board by jumping the two "test" pins.
You must be ready to yank off your jumper wire as soon as the defrost cycle begins or the accelerated time will kick it right out of defrost again (within a second).
In order to fake out the defrost board into thinking that the coil is frozen, you must jumper the two leads to the outdoor coil sensor(defrost termination thermostat) before you begin the test cycle, otherwise nothing will happen.

2. To test the defrost termination thermostat/sensor you should remove it from the circuit board, install your meter to the leads to test for impedance, remove the fan wire from the defrost board so that the outdoor fan does not run. You can just run the unit in air-conditioning or you can accelerate the defrost board into the defrost mode. Once in the defrost mode/AC mode, without running the outdoor fan will cause the oil to Frost up and freeze rather quickly. Your multimeter will indicate the circuit closing as the coil freezes. This will verify the operation of the defrost sensor. You can determine the on/off setpoints of the sensor by converting refrigeration pressures to temperature. Or, use a thermistor on the coil if it's that critical.

I have never done this procedure during a home inspection, and I see no reason to ever do it. However, I thought you might like the information if you are not aware of it.

If you don't have gas service to your house in the Tennessee, you have a heat pump around here. Multilevel homes with gas service often have a heat pump for the second-floor in the gas furnaces on the first floor. This saves money and effort to penetrate the roof to vent the furnace from the attic etc.

Also, if you would be interested in a device that easily attaches to the air-conditioning condenser to temporarily modify the air-conditioner so they can be run in the wintertime by cycling the outdoor fan, drop me a private message with your e-mail and I'll jot down a schematic for you, or take a picture of mine.

[Charley L. Bottger]

David; Yes I knew there was a way to lie to the defrost board but not practical for the HI I just try to keep it simple with most terms that can be comprehended by the average HI.

I will have been retired 5 years this next April from the HVAC business and like every thing else if you don't use it you loose it.

[David A. Andersen]

I know where you're coming from!
I've been out of it twice as long as that and I scratch my head so much these days I'm starting to go bald!

[Charley L. Bottger]

Originally Posted by dandersen

I know where you're coming from!
I've been out of it twice as long as that and I scratch my head so much these days I'm starting to go bald!

Oh bald is bad IM' just gray don't care what color it turns just as long as it does not turn LOOSE