Header – The heavy beam that is installed over an opening such as a door or window. May be wood, steel or concrete.

Hearth – The floor of a fireplace.

Heat exchanger – Internal piece of a furnace that separates the air (or in a radiator system, the water) from the flames in the burner. Transfers the heat generated by the burner to the circulating air.

Heat Loss – The loss of heat resulting in a decrease of the temperature due to heat escaping through poorly insulated walls, windows, roofs, doors etc.

Heat Pump – The same as an air conditioner, except that it can be used to heat during the winter by extracting heat from cold air.

Hip Roof – a type of roof containing sloping planes of the same pitch on each of four sides. Contains no gables.

Hip Shingles – shingles used to cover the inclined external angle formed by the intersection of two sloping roof planes.

Hot Water Heating – Heating that uses a boiler to heat hot water passes through a system of pipes and radiators. In most cases the system is pressurized and uses a circulating pump to move the hot water.