Gas water heater without ventilation duct - has thermostat under burner to shut down gas and water supply

摘要

A gas water heater without a ventilation duct includes a control system which operates to prevent excessive production of carbon dioxide, with a thermostat (1) in a tube (1a) under the burner heated by radiation from the burner, so as to operate a piston (18) and a valve member is moved from a seating (15) so that equal pressure is applied to both sides of the membrane (10) of a differential valve (28) through two lines (5, 6), this latter valve controlling the gas supply by means of a spring loaded plug (11) above the membrane and also controlling the water supply by means of a plug member (13) underneath. The gas flow is then cut off and the flow of water reduced as both the plug members travel downwards. The system then reverses as the thermostat cools down.