A space heater for the interior of a building has a support enclosure containing a gas burner and a gas conduit connecting the burner to a source of combustible gas. An electronically controlled proportional valve is located in the gas conduit. A fan and motor assembly are in the enclosure for distributing heated air from the burner when gas is communicated through the conduit and to the burner for combustion. A control system and a PC interface of a PC are located in the support enclosure to receive a data processing card having a predetermined temperature set point relating to temperature conditions within the building. A control means comprises a part of the control system and is connected to the PC to be responsive to temperature sensors in the building to cause or cease ignition of gas at the burner when any of the temperature conditions in the building varied with the predetermined temperature set point to permit the production of heat by the burner to automatically bring the varied temperature conditions in the building back towards the temperature of the predetermined temperature set point.