BULB-OPERATED MODULATING GAS VALVE WITH MINIMUM BYPASS

摘要

A valve unit provides low pressure unregulated gas flow and high pressure regulated gas flow to a burner and comprises a main diaphragm valve (4) and a bypass diaphragm valve (13) which are opened by pressure differentials on their respective valve diaphragms (9, 19). A regulator valve (26) and a snap valve (27) modify gas pressure applied to the main and bypass valves diaphragms respectively. A control means (28) actuates the regulator and snap valves based on degree of temperature deficiency sensed in a monitored space. The control means opens the snap valve (27) to provide unregulated gas flow when low gas pressure is required, and opens the regulator valve (26) to provide regulated high flow when high gas pressure is required.