The right size furnace will depend mostly on your local climate as well as the size and construction of your home. Sizing a furnace correctly is important because if it’s too small, it might struggle on the coldest days. If the furnace is too large, it can end up turning on and off frequently increasing the wear and tear on all of the components from the constant starting and stopping.

There are also 2-stage furnaces now that can heat at different capacities, as well as modulating units that match their output to the heat loss of your home in real time. These furnaces are capable of providing very high comfort and efficiency.