The sizing of the heat pump system requires two things:
- The building's heating and cooling loads, and the domestic hot water heating requirements, must be provided by the heat pump system.
- An estimate must be made of the ground heat exchanger loads given the heat pump operating hours.
The steps to follow in sizing a geothermal system are:
- Calculate the building's heating and cooling design loads using one of many methods, including:
- Hand calculations based on ASHRAE recommendations;
- Air Conditioning Contractors of America Manual J for single family detached homes; or
- Manufacturer or other accepted computer software programs.
- Select a properly-sized heat pump to serve these loads.
- Select the type of indoor distribution system. An air system is typical for single family residential and some commercial and institutional applications. A water-to-air system is often considered for larger multi-zone commercial buildings.
- Size the indoor distribution system. There are a number of manuals and some software programs that can assist the distribution system designer.
- Select the proper air supply and return diffusers, registers and grilles.
- Estimate the building's energy requirements given:
- The heating and cooling loads;
- The type and size of heat pump equipment selected; and
- The thermal characteristics of climate and soil.
- Estimate the ground heat exchanger loads, considering the annual load and the design month's load.