Inspecting Geothermal Heat Pumps

[msteger]

What is the standard regarding inspecting Geothermal Heat Pumps??

Since these are not air source systems and thus not really affected by the outside air temp, can the heating AND cooling sides both be run and tested during the inspection? If so, what sort of delay time should be used b/w heat and cool?

Thanks.

[Mark P]

I treat them the same as an air sourse heat pump and only test them in the mode they are in.

Most do not have a back up, (don't know why you would need one) but some do and I'll check it.

I'll take temp readings. Look at overall condition, any leaks, etc. The biggest challange is explaining to the customer how it works. Often time it is also hooked into the water heater to assist in the heating of the water. If the installer left a label (phone #) on the unit I tell the customers to call them and learn what they can about past maintenance, future maintenace requirements.

Here is an informative site.. http://www.geoexchange.org/

[msteger]

If the geothermal unit is running in cool mode, will you still test it in backup heat mode (but not regular heat mode)? I am doing a 6,000 sq ft vacant home with a dual geothermal HP system. I think there is also an LP fired boiler and holding tank for the potable water. The system must have cost a fortune.

I don't know if it has a backup.. I wouldn't imagine a backup heat source is needed for a geothermal unit since its not interacting with the outside air. Would running it in cool and heat mode do damage to a geothermal unit?

[waynesoper]

The unit should operate within the same temp differentials on either side. Real exterior temp would decide which was best to test. If one sides ok the other should be also. If there is an electric backup heat then that gets tested separately.

[Bill Kibbel]

I don't know if it has a backup.. I wouldn't imagine a backup heat source is needed for a geothermal unit since its not interacting with the outside air.

Most geothermal systems in this area and north have auxiliary heat. These systems are mostly sized according to cooling loads. This usually results in the system only supplying about 80-85% percent of the heating load. I've had no issue operating the auxiliary heat after operating in the cooling mode.

[msteger]

OK, so determining whether to run the geothermal HP in cool or heat mode is still done using the outside temp, like just air source units? If above ~62 degs., run it in cool mode. If less than ~62 degs, run in heat mode. And, like with air source systems, if the geothermal unit is only run in cool mode, the electric or gas/LP backup can still be run. Wasn't sure if anything special had to be done from air source units, other than looking for leaks.

Sounds like a plan. Thanks.

[Jim Katen]

OK, so determining whether to run the geothermal HP in cool or heat mode is still done using the outside temp, like just air source units? If above ~62 degs., run it in cool mode. If less than ~62 degs, run in heat mode. And, like with air source systems, if the geothermal unit is only run in cool mode, the electric or gas/LP backup can still be run. Wasn't sure if anything special had to be done from air source units, other than looking for leaks.

Sounds like a plan. Thanks.

Matt,

With a ground source heat pump, you can run it in any mode you want whenever you want. Just give it a couple of minutes between heating & cooling.

- Jim Katen, Oregon

[msteger]

Thanks Jim.

[msteger]

I ran both geothermal systems in cool mode. A 5 ton unit cooled the basement and main level. A 2 ton unit cooled the 2nd level. I noticed only a 2 or 3 degree delta at the 2nd level and found an iced over evaporator coil in the 2 ton unit. 18 degree delta with the other unit. I ran both units in backup mode and each worked OK in that mode. The pump motor for the system was rather noisy and would annoy me if I lived there, however. It sounded like a factory motor.