A. In mild weather the HP can provide all the necessary heat down to about 30-35 degrees, below that it would need some kind of backup heat source to provide the additional heat necessary to meet the load of the home down to 0 degrees.

A. The HP is designed to heat the air about 20 degrees each time the air goes through the system. A gas or oil furnace is designed for a 40-70 degree temperature rise as the air passes thru the furnace. So if you maintain 70 degrees in the home, a heat pump will put out about 90 degree air depending on the outside temperature. Since the normal body temperature is 98.6 degrees this 90 degree air feels cool to us.  In comparison a gas or oil furnace normally warms the air to between 110 - 140 degrees or higher and therefore it feels warm to us.