22
Gas input to the boiler can be adjusted by removing the
protective cap on the pressure regulator, and turning
the screw clockwise
to increase input and
counterclockwise
to decrease input. The manifold
pressures are taken at the outlet side of the gas valve.
To check for proper fl ow 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 fl ow 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. Figures 15-17.
Burner orifi ces should be changed if the fi nal manifold
pressure varies more than plus or minus 0.3 inches
water column from the specifi ed 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. Ignition system
safety shutoff device must be tested after placing boiler
in operation. (Figures 15-17 on previous pages)
1. Pilot: With main burner operating, turn the pilot
gas adjusting screw clockwise
until pilot gas
is turned off. Within 90 seconds the main gas
control should close, shutting off the gas to the
main burner.
2. High Limit Control: Remove cover and note
temperature setting. Decrease this setting to
minimum and operate boiler. When the boiler water
temperature exceeds the control temperature
setting, the control will open the circuit, closing
the automatic main gas valve. Figure 22.
CHECKING GAS INPUT RATE TO BOILER
GAS VALVE
BURNER ACCESS
DOOR
HIGH LIMIT
AND OPERATING
CONTROL
Figure 22 - High Limit Control Location
