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Combination Gas Valves
WIRING TERMINALS
PRESSURE REGULATOR
ADJUSTMENT
(UNDER CAP SCREW)
INLET PRESSURE TAP
G
A
S CONTROL KNOB
PILOT OUTLET
OUTLET
PRESSURE TAP
Figure 3-5_M9 Gas Valve
Venting of Combination Gas Valves
The combination gas valve regulator used on all
mod els is equipped with an integral vent limiting
orifice. The vent limiter ensures that the volume of
gas emitted from the valve does not exceed the
maximum safe leak age rate allowed by agency
re quire ments. Com bi na tion gas valve/regulators
equipped with integral vent limiters are not
re quired to have vent or relief lines piped to the
outdoors. A dust cap is provided at the vent
termination point on the valve to prevent block age
of the vent limiter by foreign material. The
com bi na tion gas valve regulator with an integral
vent limiter complies with the safety code
requirements of CSD-1, CF-190(a) as shipped from
the manufacturer with out the in stal la tion of
additional vent lines.
Two Stage Burner Control System
The 45,000 thru 260,000 Btu/hr boilers (M9) are
equipped with a two stage burner control system.
Each unit has a combination gas valve to control the gas supply to the
burners. The com bi na tion valve con sists of a gas regulator and two valve
seats to meet the requirements for redundant gas valves. The valve has a
gas control knob that must remain in the open po si tion at all times when
the appliance is in service. Each gas valve has pres sure taps located on the
inlet and outlet sides. Manifold pressure is adjusted using the regulator
located on the valve. The manifold pres sure is pre set at the factory and
adjustment is not usu al ly re quired. If the manifold pressure is to be
ad just ed, follow the “Gas Manifold Pressure Ad just ment Pro ce dure”,
page 20 for proper adjustment.
3 Gas connections
22
Installation & Service Manual