goethermal heat pump 10 degree delta T?

Jake Timmerman_3

For a few months now, I have been installing radiant jobs for a geothermal heatpump salesman. When designing the primary loop or the piping loop for the heat pump, I was told that you must keep a 10 degree delta T across the heat exchanger. This is because of efficiency issues. Is this true? It makes for some expensive piping and pumps.

I am still undecided about heat pumps so far. Some jobs are just better suited for a condensing boiler than a heat pump. The heat pumps I have been installing only go up to 56000 btu/hr so on a larger house you need 2 or 3 units with a max output temp of 120. Then on top of that you need to space the pex on 6" centers throughout the whole house, witch isn't a bad thing to do anyway, but costly. This is getting to be very high upfront costs. I have been subcontracted out to do these jobs and wish I could of told these people there options, but now I keep my mouth shut.

Glenn Harrison_2

I just looked in my Water Furnace book...

and it shows that the load side temp ride will be anytime between 4° and 18°, depending on the loop (source) temp. The source temp drop will be 4° to 8° on a closed loop or 10° to 17° if it's an open (well) loop.

Also, the max temp out of their units is 130°, which is o.k. for radiant, but you do have to keep it in mind when designing the systems.

Hope this helps.

don_50

We

> and it shows that the load side temp ride will be

> anytime between 4° and 18°, depending on the loop

> (source) temp. The source temp drop will be 4° to

> 8° on a closed loop or 10° to 17° if it's an open

> (well) loop.

>

> Also, the max temp out of their

> units is 130°, which is o.k. for radiant, but you

> do have to keep it in mind when designing the

> systems.

>

> Hope this helps.