Smith Cast Iron Boilers GB300 - Manual (Page 43)

GB300 BOILER INSTALLATION AND OPERATION INSTRUCTIONS
Page 43
6. Remove the front grill(s).
7. Connect a manometer having a minimum capacity
of 20" WC to the outlet pressure port of the gas valve.
Make sure that the gas supply piping has been purged
of air and that all gas joints up to the gas valve have
been thoroughly checked for leaks.
8. Open the petcock pilot valve.
9. Turn on all electric power to the boiler.
10. Set the operating control to the desired setting.
11. The pilot(s) should automatically light. Do not try to
light the pilot(s) by hand!
12. With the pilot(s) lit, open the main gas shut-off valve.
13. The burners should light with proper boiler operation.
14. A boiler designed for use with natural gas should
have a manifold gas pressure of approximately 3.5" WC
on high fire and 0.8" WC on low fire. For an LP boiler,
the manifold pressure should be 10" WC. To adjust the
manifold gas pressure see the GAS PRESSURE
ADJUSTMENT instructions in the BOILER CHECKING
AND ADJUSTMENT section.
15. With the burners in operation, close the manual
shutoff valve in the gas supply line. As soon as the main
burner flames go out, open the manual shutoff valve. A
normal ignition sequence should take place. If the
burners fail to light the system will make two more
ignition attempts. If the burners have not lit after the last
ignition try, the gas valve will close and the system will
go into lock out. DO NOT attempt to reset the system
until the ignition system has been inspected and the
problem resolved.
With the burners in operation, interrupt the power to the
control circuit by lowering the operating control. The main
burners should go out. Reset the operating control, a
normal ignition sequence should follow.
To test the ignition safety shutoff device, close the
manual shutoff valve in the gas supply line. Within 6
seconds of main burner flame extinction, the main gas
valve solenoid should close with an audible noise.
A sparking noise should be heard while the ignition
module tries to light the pilot. After 1 minute the module
should lockout and the try for ignition end. Open the
manual shutoff valve in the gas supply line and reset the
ignition control system. A normal ignition sequence
should take place.
To Turn Off Gas To Boiler
1.
Set the operating control to its lowest setting.
2. Turn off all electric power to the appliance if service
is to be performed.
3. Close the manual main and pilot gas shut-off valves.
BOILER CHECKING & ADJUSTMENT
PILOT ADJUSTMENT
The pilot burner flame should envelope 3/8" to 1/2" of
the thermocouple tip or flame-sensing probe, depending
on the pilot type. Figure 103 depicts an intermittent pilot,
but the adjustment dimensions for a continuous pilot
would be the same. To adjust the pilot the following steps
must be taken:
1. Remove the cap next to the pilot tube fitting on the
gas valve or on the separate pilot gas regulator where
one is used.
2. Turn the pilot adjustment screw on the valve
counterclockwise to increase the flame, clockwise to
decrease it. On the separate pilot gas regulator turn the
regulator screw clockwise to increase the flame,
counterclockwise to decrease it.
3. Replace the pilot adjustment screw cap.
Figure 103 Pilot Flame Adjustment
Gas Pressure Adjustment
NATURAL GAS: Optimum results are obtained when
the boiler is operated at its full input rating, with 3.3" WC
to 3.7" WC and 1.0" to 0.8" on low fire of manifold
pressure. The manifold pressure should not vary outside
this range. The gas valve pressure regulator has been
preset at the factory. If adjustment is necessary the
following steps must be followed:
NOTE: The Honeywell VR8404 valve is factory set
and cannot be field adjusted
SCREWS
BRASS FERULE
1/4" TUBING