Heating & Cooling

The first step in sizing geothermal heat pumps for any installation is to calculate the heating and cooling loads of the structure. This can be done using any one of many manual or computerized load calculating methods.

Once the cooling and heating loads are known, a decision must be made on equipment selection. Should the equipment size be based on the heating load or the cooling load? In northern climates where heating operation predominates and cooling operation is minimal or non-existent, optimum heat pump size may be between 65 to 75 percent of the design heating load. In some cases, units with two-speed compressors may be considered. This would accommodate sizing to, or oversizing on the heating side, while allowing desirable operation for cooling.

In mild climates where heating and cooling operation is nearly equal, the heat pump may be sized to meet the heating load; however the cooling capacity should not exceed the cooling load by more than 25 percent.

In very warm climates where the cooling load predominates, size as close to the cooling load as possible. Do Not Undersize the cooling unit in warm climates.

Proper equipment sizing may require the installation of supplementary electric heaters to maintain indoor comfort on those days when the heating load of the structure exceeds the heating capacity of the heat pump.