Redundant
Solenoid 
INLET
ON/Off
Switch
Inlet Pressure Tap
(Side of Valve)
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O | P | 3 | |
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F |
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F | C | 2 | |
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ON
Main Regulator
Adjust
Main
Solenoid
OUTLET
Outlet Pressure Tap
(Side of Valve)
Figure 39
White Rodgers Model 36E22
CHECK GAS INPUT AND PRESSURES
Gas supply pressure and manifold pressure with the burn- ers operating must be as specified on the rating plate.
CHECKING GAS PRESSURE
Gas inlet pressure should be checked and adjusted in accordance to the type of fuel being consumed.
With Power and Gas Off:
1.Honeywell Model VR8205, or White Rodgers Models 36E36 or 36E22, or Robertshaw Model 7222: Connect a water manometer or adequate gauge to the “inlet pressure tap” of the gas valve.
As an alternative method, inlet gas pressure can also be measured by removing the cap from the drip leg and installing a predrilled cap with a hose fitting (Figure 41).
With Power and Gas On:
2.Put furnace into heating cycle and turn on all other gas consuming appliances.
| Inlet Gas Pressure |
Natural | Min. 5.0" W.C., Max. 10.0" W.C. |
Propane | Min. 11.0" W.C., Max. 14.0" W.C. |
Inlet Gas Pressure Must Not Exceed the Maximum Value Shown.
Figure 40
Figure 41
Measuring Inlet Gas Pressure
(Alternate Method)
CHECK MANIFOLD PRESSURE
A tapped opening is provided in the gas valve to facilitate measurement of the manifold pressure. See the “Outlet Pressure Tap” in Figures 36, 37, 38, & 39. A “U Tube” manometer having a scale range from 0 to 12 inches of water should be used for this measurement. The manifold pressure must be measured with the burners operating .
To adjust the pressure regulator, remove the adjustment screw or cover on the gas valve. Turn out (counterclockwise) to decrease pressure, turn in (clockwise) to increase pres- sure. Only small variations in gas flow should be made by means of the pressure regulator adjustment. For natural gas, the manifold pressure must be between 3.2 and 3.8 inches water column (3.5 nominal). For propane gas, the manifold pressure must be between 9.7 and 10.3 inches water column (10.0 nominal). Any major changes in flow should be made by changing the size of the burner orifice.
CHECK GAS INPUT (NATURAL GAS ONLY)
To measure the gas input using the gas meter proceed as follows:
1.Turn off gas supply to all other appliances except the furnace.
If operating pressures differ from above, make necessary pressure regulator adjustments, check piping size, etc., and/or consult with local utility.
2.With the furnace operating, time the smallest dial on the meter for one complete revolution. If this is a 2 cubic foot dial, divide the seconds by 2; if it is a 1 cubic foot dial, use the seconds as is. This gives the seconds per cubic foot of gas being delivered to the furnace.
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