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3
Gas connections
Combination Gas Valves
PRESSURE REGULATOR
ADJUSTMENT
WIRING TERMINALS
(UNDER CAP SCREW)
INLET PRESSURE TAP
S CONTROL KNOB
GA
Figure 3-5_M9 Gas Valve
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.
22
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
OUTLET
re quire ments.
PRESSURE TAP
equipped with integral vent limiters are not
re quired to have vent or relief lines piped to the
outdoors.
termination point on the valve to prevent block age
of the vent limiter by foreign material.
PILOT OUTLET
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.
Installation & Service Manual
Com bi na tion gas valve/regulators
A dust cap is provided at the vent
The
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