Lochinvar 90 Combination Gas Valves, 3Gas connections continued, Installation & Service Manual

3Gas connections (continued)

Combination Gas Valves

Installation & Service Manual

PRESSURE REGULATOR ADJUSTMENT (UNDER CAP SCREW)

INLET PRESSURE TAP

OUTLET

PRESSURE TAP

PILOT OUTLET

Each unit has a combination gas valve(s) to control the gas supply to the burners. The 500,000 Btu/hr model has two combination gas valves to supply gas to the burners. The combination valve consists 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 position at all times when the appliance is in service. Each gas valve has pressure taps located on the inlet and outlet sides. Manifold pressure is adjusted using the regulator located on the valve. The

RED RESET BUTTON GAS CONTROL KNOB

Figure 3-5_F1 Gas Valve, standing pilot

manifold pressure is preset at the factory and adjustment is not usually required. If the manifold pressure is to be adjusted, follow the “Gas Manifold Pressure Adjustment Procedure”, page 21 for proper adjustment.

Venting of Combination Gas Valves

PRESSURE REGULATOR
ADJUSTMENT (UNDER CAP SCREW)	WIRING TERMINALS

INLET PRESSURE TAP

OUTLET

PRESSURE TAP

PILOT OUTLET

The combination gas valve regulator used on all models 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 leakage rate allowed by agency requirements. Combination gas valve/regulators equipped with integral vent limiters are not required 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 blockage of the vent limiter

GAS CONTROL KNOB

Figure 3-6_F9 Gas Valve, spark ignition

by foreign material. The combination 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 without the installation of additional vent lines.

Two Stage Burner Control System

The 315,000 through 399,999 Btu/hr boiler models (M9) will be equipped with a two stage gas valve to control high/low burner operation. The 500,000 Btu/hr boiler model achieves two stage burner firing by staging the operation of the two combination gas valves.

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