Pilot flame controlled flue gas extractor appts. - uses thermocouple in pilot flame to switch supply to electric motor driving flue gas extraction fan

摘要

The gas heater has a burner placed near its base and a coil heat exchanger above the burner. The burner is ignited by the pilot light, and a thermocouple placed near the pilot flame controls a switch to start the electric motor driving the exhaust fan. The exhaust fan is horizontally mounted at the top of the heater combustion chamber and directs flue gas out the flue which preheats inlet air. The switch is situated on the hood which contains the ventilator-extractor arrangement. The latter operates either at a reduced speed or max. speed and stops only after a set time interval. The time interval is a function of the difference of the switching temps. of the thermocouple, the heat output of the pilot light and the specific heat of the thermocouple mount.