If you are planning to buy a new heat pump, pay attention to the recent technological innovations and its energy-efficiency coefficient.
Heat Pumps Heating Efficiency rating
Heat Pump Energy-Efficiency Coefficients
HSPF (heating efficiency)
SEER (cooling efficiency, central air heat pumps)
EER (cooling efficiency, ductless heat pumps).
High HSPF: 9-10 or more.
Central air heat pump SEER: 18 or more;
Room air heat pump EER: 13-14 at least.
New heat pumps can provide 50% more heat or cool air than the units of some years ago.
Old air source heat pumps were rated by their Coefficient of Performance (COP), which is still used in geothermal heat pumps.
A COP or 2 means that the heat pump is able to produce 2 kWh of heat with 1 kWh or electricity, while a coefficient of 3 means that it is able to produce 3 kWh or heat with 1 kWh or electricity… Something that top geothermal heat pumps can easily meet.
Modern energy-efficiency air source heat pumps are rated by their Heating Season Performance Factor (HSPF).
Top heat pumps have an HSPF between 8 and 10 (a HSPF of 6.8 corresponds to a COP of 2).
Heat Pumps Cooling Efficiency rating
Modern heat pumps have also two cooling efficient coefficients (the same of air conditioners): the SEER (Seasonal Energy Efficiency Ratio), for central heat pump systems; and the EER (Energy Efficiency Ratio) for individual room units. A SEER of 13 is equivalent to an EER of 11 (and to a COP of 3.2). Modern energy-efficient heat pumps have SEERs above 18 (and slightly smaller EERs).
Pay close attention to cooling efficiency ratings if you live in a hot or moderate climate. Choose a heat pump with a high cooling efficiency coefficient. New efficient heat pumps have SEERs between 14 and 18 and HSPFs between 8 and 10. In warmer climates you should consider a high SEER coefficient; in colder climates you should focus your attention on the HSPF coefficient.
The climate & Heat Pumps for Cold Climates
The heating efficiency of a heat pump depends also on the outside ambient temperature and installation issues.
When temperatures drop close to freezing, traditional heat pumps become ineffective at providing heat and they have to resort to their electric-resistance elements to provide heat.
In other words: the heating coefficient ( HSPF) drops in cold temperatures: a reason why air source heat pumps were mostly used in moderate climates, without freezing temperatures.
The heat pump performance depends on
- its energy-efficiency coefficients but also on a proper...
- duct size;
- refrigerant charge;
- outside temperatures.
Fortunately things are changing. There are now “cold climate air source heat pumps”, able to largely overcome traditional limitations; cold-climates heat pumps are no more an experimental concept (see: New Heat Pumps).
Other factors that affect the heat pump performance
Heat pumps are very sensitive to airflow and refrigerant charge problems (much more than furnaces or boilers), which in turn depends on regular maintenance and installation, sizing and duct issues (in the case of central heat pumps)
Some new features - multi-speed fans, demand-defrost controls... - can help minimize some of these problems, but a good installation and a good maintenance and sizing are critical.
Many heat pumps fall short of expectations due to these factors, and you should be aware of them.
Energy Star Heat Pumps Rating
In USA or Canada the easiest way to choose a good heat pump is to look for an Energy Star model. Energy Star is listing over 750 certified models...
Heat Pump Manufacturers
Heat pump manufacturers are well known air-conditioner manufacturers: Carrier, York, Danfoss, Daikin, Sanyo, etc. See: Heat Pumps Manufacturers and Associations.