Posts Tagged ‘generators’

Geothermal Heat Pumps and Generator Sizing

Tuesday, May 11th, 2010
Dan Frawley

Dan Frawley

Geothermal heat pumps require more power during start up than while running.  In order to choose a backup generator, you need to calculate the starting wattage of the heat pump plus the running wattage of all other electrical components.

Be Aware of Locked Rotor Amperage

Many customers with geothermal systems also need backup generators due to remote locations or frequent power failures.  Locked Rotor Amperage refers to the current required to start the heat pump from rest, and is much larger than the current required for operation.  Unfortunately, you will need to purchase a larger backup generator.
Calculate Load / Select Generator

The most important piece of information you need to know is how much electrical power you will need for your specific situation because nothing will be as disappointing as purchasing an underpowered generator. You need to determine all the electrical devices you plan on running with the generator.

Most small electrical appliances run on 120 volts but there are larger appliances, such as a geothermal heat pump, that run on 240 volts.  It is important to note that if you need to run any 240volt devices you need to get a generator that is capable of 240-volt output.

The next step is determining the power requirement of your appliances in watts.  This can be fairly easy as most devices are described by their wattage; in the case of light bulbs the wattage is printed on the bulb itself.  If the device doesn’t provide a wattage requirement, you can determine watts by multiplying volts times amps.