Generator Sizing is a very important step in the process of buying and installing a generator system. If the generator is too small the generator system will not be able to carry the building load and will shut down, leaving no backup power to the home. If the generator is too big the customer ends up with more of a capital investment than he or she needs to make.

We at Hunter & Lomison have spent over 30 years sizing generator systems, all the way from small air-cooled home backup systems to large industrial systems for factories, municipal waste systems, etc,  always learning about new products and sizing methods. Over the years we developed a sizing form for our customers to complete to aid in the determination of the correct generator and transfer switch according to their needs and wishes. The customer fills out the form, we review it using various sizing methods, and then sometimes request additional information.

Additional information is usually needed when the customer has a heat pump system for the home. Great care is required when sizing a generator system for backup electrical heat. Lockout contactors can be used to eliminate the heating system while running under generator power. This method is used when the homeowner doesn’t want to exceed the cost of an air-cooled generator system. However, if the customer requires a backup heat system and has a larger budget, we can size a larger liquid-cooled generator to meet those power demands.

These are some of the challenges of correctly sizing a home generator system. Please call or email us for a free, no obligation, generator sizing and quote.

Home Generator Sizing Worksheet