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Gas input to the boiler can be adjusted by removing the
protective cap on the pressure regulator (Figures 14-
16 on pages 15-16) and turning the screw clockwise
_"_to increase input and counterclockwise
f-'_'-, to decrease input. Natural gas manifold
pressure should be set at approximately 3.5 inches
water column. Propane gas manifold pressure should
be set at approximately 11 inches water column.
These manifold pressures are taken at the outlet
side of the gas valve. (Figures 15 and 17 on pages
16-17) To check for proper flow of natural gas to the
boiler, divide the input rate shown on the rating plate
by the heating value of the gas obtained from the
local gas company. This will determine the number
of cubic feet of gas required per hour. With all other
gas appliances off, determine the flow of gas through
the meter for two minutes and multiply by 30 to get
the hourly rate. Make minor adjustments to the gas
input as described above.
Burner orifices should be changed ifthe final manifold
pressure varies more than plus or minus 0.3 inches
water column from the specified pressure.
Primary air adjustment is not necessary, therefore air
shutters are not furnished as standard equipment.Air
shutters can be furnished on request where required
by local codes or conditions.
CHECK SAFETY CONTROL CIRCUIT after burner
adjustments are made for satisfactory operation.
1. Pilot: With main burner operating, turn the
pilot gas adjusting screw clockwise _
until pilot gas is turned off. (Figures 14-16 on
pages 15-16) Within 90 seconds the main gas
control should close, shutting off the gas to the
main burner.
2. High Limit Control (Figure 22): Remove
cover and note temperature setting. Decrease
this setting to minimum and operate boiler. When
the boilerwater temperature exceeds the control
temperature setting, the control will open the
circuit, closing the automatic main gas valve.
Front Lower
Gas Valve
IFIGURE 221
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