Figure 4-27.An automatic gas burner control system.
Figure 4-28.A gas pressure regulator.
The recycling solenoid gas valve shown in figure
4-30 can be used with the same heating equipment as
the standard solenoid gas valve. The design of this
valve differs from that of the standard solenoid gas
valve, because it is equipped with an automatic
recycling device that allows the valve to switch to
manual operation during power failure. However,
upon the resumption of power, the thermostat
automatically resumes control of this valve.
DIAPHRAGM VALVE.The diaphragm gas
v a l v e s h o w n i n f i g u r e 4 - 3 1 c a n b e u s e d
Figure 4-29.A standard gas solenoid valve.
interchangeably with a solenoid gas valve. Its main
feature is the absence of valve noise when it is opening
or closing. In this type of diaphragm valve, the relay
energizes and opens the three-way valve, so the gas
pressure on the top of the diaphragm is released to the
atmosphere. Reducing the pressure on the top of the
diaphragm in this manner causes the gas supply
pressure to flex the diaphragm upward, opening the
main gas valve. When the relay is de-energized, the
vent to the atmosphere is sealed and pressure from the