Water to Water Heat Pumps (UNCLASSIFIED)

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The help file (press F1 on any screen in TRACE) and User's Manual are pretty helpful with how to model geothermal heat pumps, I would suggest reading through those first. In terms of modeling the appropriate ground loop temperatures and associated WWHP efficiency, there are a couple of ways of doing it (see help file and User's manual for specifics). Just keep in mind that when you create a new WWHP in the Cooling Equipment library and define the Full Load Energy Rate and the Design Entering Condenser Water Temperature, you need to base them on the worst case entering loop temperatures over the year. TRACE assumes you enter the efficiency at the hottest and coldest entering condenser temperatures for Cooling and Heating efficiency respectively and then uses the Power Consumed and Ambient Modification Unloading Curves to adjust the efficiency for air-side load and change in entering loop temperature.


I'm a little rusty on eQUEST, but this is how I remember it. You can enter the ground and well properties for your site and system which will be the basis of entering loop temperature for the equipment as a function of the load on the equipment over the year. eQUEST wants the equipment efficiency at ARI conditions and then you enter the unloading curves (see help/Documentation for more info on this). The concept here is similar to TRACE but from what I remember it is more detailed.


Alex Chapin, E.I.T., LEED AP BD+C

Message: 1

Date: Tue, 22 Feb 2011 10:37:34 -0600

From: "Eurek, John S NWO" >



Subject: [Trace-users] Water to Water Heat Pumps (UNCLASSIFIED)


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The EER of WWHP can vary from 11.8 to 23.3 depending on the water temperature returning from the well field. Can Trace model this?

We are designing a lot of geo-thermal heat-pumps. If we can't model the benefit of the well-field accurately, we can't model the energy use.

John Eurek PE, LEED AP

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