Geothermal Heat Pumps Key Product Criteria
|Requirements (Effective January 1, 2012)
|Closed Loop Water-to-Air
|Open Loop Water-to-Air
|Closed Loop Water-to-Water
|Open Loop Water-to-Water
Models must meet or exceed the energy efficiency ratio (EER) and coefficient of performance (COP) values in the tables above.
The specifications in the charts above apply to single stage models. Multi-stage models may be qualified based on:
- EER = (highest rated capacity EER + lowest rated capacity EER) / 2
- COP = (highest rated capacity COP + lowest rated capacity COP) / 2
Commercial (i.e., 3-phase) units are not eligible for qualification under the ENERGY STAR specification at this time.
AHRI 870 for DGX systems.
ISO 13256-1 for water-to-air models (open and closed loop systems).
ISO 13256-2 water-to-water models (open and closed loop systems).
- Geothermal Heat Pump
- A geothermal heat pump uses the thermal energy of the ground or groundwater to provide residential space conditioning and/or domestic water heating. A geothermal heat pump model normally consists of one or more factory-made assemblies that include indoor conditioning and/or domestic water heat exchanger(s), compressors, and a ground-side heat exchanger. A geothermal heat pump model may provide space heating, space cooling, domestic water heating, or a combination of these functions and may also include the functions of liquid circulation, thermal storage, air circulation, air cleaning, dehumidifying or humidifying. A geothermal heat pump system generally consists of one or more geothermal heat pump models, the ground heat exchanger(s), the air and/or hydronic space conditioning distribution system(s), temperature controls, and thermal storage tanks.
- Geothermal heat pumps that are designed to operate at one stage and one capacity.
- Geothermal heat pumps that are designed to operate at more than one stage or capacity through the use of technologies such as multiple stage compressors, dual compressors, variable speed compressors, etc. Multi-stage models are more efficient while running at lower capacities, but have the capability to supply more heating or cooling using higher capacities when required.
- Closed Loop
- A ground heat exchange method in which the heat transfer fluid is permanently contained in a closed piping system. Also called a ground-loop system.
- Open Loop
- A ground heat exchange method in which the heat transfer fluid is part of a larger environment. The most common open loop systems use ground water, reclaimed water, or surface water as the heat transfer medium. Also called a ground-water system.
- A geothermal heat pump model that provides space conditioning primarily by the use of an indoor air heat exchange coil. Water-to-air models may also provide domestic water heating and hydronic space heating by using desuperheater and/or demand water heating functions.
- A geothermal heat pump model that provides space conditioning and/or domestic water heating by the use of indoor refrigerant-to-water heat exchanger(s). Water-to-water models may provide domestic water heating by using desuperheater and/or demand water heating functions.
- Direct Geoexchange (DGX)
- A geothermal heat pump model in which the refrigerant is circulated in pipes buried in the ground or submerged in water that exchanges heat with the ground, rather than using a secondary heat transfer fluid, such as water or antifreeze solution in a separate closed loop.
- Coefficient of Performance (COP)
- A measure of efficiency in the heating mode that represents the ratio of total heating capacity to electrical energy input. For the purpose of this specification, COP will be calculated for closed loop and open loop systems in accordance with the International Standards Organization (ISO) Test Standard 13256-1 or 13256-2 as stated in Section 5 below. For DGX systems, COP will be calculated in accordance with the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) 870 conditions.
- Energy Efficiency Ratio (EER)
- A measure of efficiency in the cooling mode that represents the ratio of total cooling capacity to electrical energy input. For the purpose of this specification, EER will be calculated for closed loop and open loop systems in accordance with ISO 13256-1 or 13256-2 as stated in Section 5 below. For DGX systems, EER will be calculated in accordance with AHRI 870 conditions.