The actual unit size should be within 15 percent of the calculated load. Heat pumps that are too large waste energy and do not provide proper humidity control. While the article focuses on air conditioning, the same principles apply to heat pumps. It may be advantageous to specify two-speed or variable speed systems where heating requirements are much greater than cooling, to assure good humidity control. Finally, the contractor should examine ways to use the geothermal system to provide hot water.
Proper installation is a key to success.
The GHPC recommends that consumers employ experienced contractors who will provide the names of customers with comparable systems. Dealing with experienced professionals who size and install ground loops is essential.