3 steps for effective geothermal installation
As homes are being built tighter, old rules of thumb don't apply for sizing HVAC equipment.
Heating and cooling loads may be a lot less than what a traditional home may experience. That's why it's important to use best practices to size and design a geothermal heating and cooling system.
Here are some steps to follow through the design process:
1. Start with a contractor that has been properly trained and certified by a manufacturer and/or a geothermal organization such as the International Ground Source Heat Pump Association.
2. Understand the best way to determine the correct size of heat pump for the home. A contractor must use a Manual J heat gain and loss calculation according to Air Conditioning Contractors of America standards. Insist that your contractor conduct a Manual J, or find a new one.
By using the Manual J methodology, HVAC designers can accurately determine the amount of heat that is lost through the exterior of a home during the cooler months, and the amount of heat that is gained through the exterior of a home during warmer months.
Through a series of inputs and calculations, the HVAC designer is able to analyze all aspects of the thermal characteristics of the walls, floors, ceilings, doors and windows in a home. An HVAC load calculation also takes into consideration other factors such as the home’s geographic location, orientation to the sun, envelope tightness, duct leakage, lights and appliances. Also, the Manual J determines the heat and humidity that each occupant of the house adds to the home.
3. Design the entire system based on the Manual J. Manufacturers such as Bosch Thermotechnology offer software to calculate the proper size of the ground source heat pump, the ground loop, and duct system based on the Manual J calculations. The software takes into account the location and climate where the unit will operate.
Properly sizing the ground source heat pump and loop for the home and climate are essential. A heat pump that's too big or too small won't perform well, not providing the even level of comfort for which geothermal HVAC is well known. An improperly sized unit could have a shorter service life as well.
A ground loop that's not sized properly won't provide the proper energy exchange with the ground, leading to greater energy use and less comfort in the home.
If you're thinking of geothermal heating and cooling for your home, work with a certified HVAC professional to get the right system for your home.