Performance characteristics for 5.5 ton Closed Loop Ground Source Heat Pump (GSHP) units from McQuay, WaterFurnace and Maritime are found below. All units are Energy-Star rated. The name plate performance characteristics are very similar for the three units, based on International Organization for Standardization (ISO) criteria.

Experienced system engineers will be aware that ISO 13256-1 ratings for heat pumps do not represent actual operation conditions,  and that loop design should not be based on ISO. The ratings do give a reasonable starting point for equipment selection, but heat exchanger and compressor durability are more important. Ratings for the three units are nearly identical.

EER, Energy Efficiency Rating, range from a low of 18.0 EER for the McQuay to a high of 19.5 EER for the WaterFurnace. EER records cooling efficiency at 80 degrees F indoor and 95 degrees F outdoor temperatures. It measures steady-state efficiency, the efficiency of the unit once running. EER is expressed in BTUH / Watt, the rate of heat energy removal divided by the rate of electrical energy input..

To promote GSHP technology, federal legislation provides a 30% investment tax credit. There also is a NYS tax credit.

Separate from tax credits, NYSERDA provides a $600./ton (1 ton = 12,000 BTUH) incentive; it can become uneconomical because additional measures selected by an outside consultant must be implemented for a project to qualify. NYSERDA need to rethink the New Construction program. GSHP should qualify as a pre-approved measure; there’s a long track record of operational electrical efficiency.


HPAC’s recent article on GSHP for commercial buildings:

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