Gas Control Valve; Measuring Gas Pressures - A.O. Smith SERIES 120 Service Handbook

GAS CONTROL VALVE

This gas valve is a 24 volt AC combination-step opening valve. It includes two valves
assembled in parallel, connected by a wiring harness. Note that the valves have fixed
pressure regulation and are not adjustable. However, the manifold (outlet) pressure is
adjustable as described on the next page.
IMPORTANT:
• For complete device shut-off, both gas control knobs must be in the OFF position.
• Both gas control knobs must be in the same position for operation or shutoff.
• Do not alter or remove the wiring harness.
• Do not apply a jumper across the valve lead wires or short them together.
Inlet Pressure Taps
Gas Control Knobs
Manifold Pressure
Taps
Wiring Harness

Measuring Gas Pressures

The supply gas pressure is measured at the inlet pressure tap when the gas is flowing. The
manifold gas pressure is measured at the manifold pressure tap when the gas is flowing.
Servicing should only be performed by a Qualifi ed Service Agent
OPERATION AND SERVICE
Inlet
Outlet
TOP VIEW OF GAS VALVE
Figure 12
16
Main Gas
Regulators
(Outlet Pressure
Adjustment)