Page 18 | LAARS HEATING SYSTEMS |
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gas supply, the automatic safety shutoff devices must be checked.
1.Before beginning the tests, make sure the main manual gas valve, and any other heater firing valves are in the “OFF” position.
2.Make sure the heater’s power switch is in the “ON” position. After placing the manual pilot gas valve in the open position and resetting all safety devices, (high limit, pressure switch, low- water cutoff, etc.) pilot(s) can be lit following the procedure located on the heater rating plate.
3.Once the pilot(s) is lit and has been established for five minutes, the flame failure response time should be checked as follows:
Systems 9 and 4 - (Intermittent ignition): With this system pilots are automatically lit when the operating controls call for heat. If the pilot flame fails for any reason, the main valve is shut off within one second and the pilot spark ignition is initiated until the pilot flame has been reestablished. On propane systems, unit locks out for safety. This sequence should be checked by turning off the manual pilot gas valve, and, at the same time, monitoring the audible sparking at the pilot burner and signal interruption to the main valve.
Caution
Propane gas is heavier than air and sinks to the ground. Exercise extreme care in lighting the heater when so equipped.
System 16 - (Electronically supervised standing pilot system): Extinguish the pilot flame by placing the manual pilot valve in the closed position, and at the same time, begin recording the time it takes for the output signal from the electronic ignition control to be interrupted. The signal interruption can be detected either with a test light or a voltmeter. The response time should never exceed one second.
4.With the pilots lit, initial activation of the main burners can be achieved by slowly opening the main manual valve. The result should be a smooth lighting of the main burners.
Hi-Limit Checkout:
After running the heater for a long enough period, bring the water temperature within the range of the
3C. To Start Up System:
1. Start Up Boiler
Be certain system pump is running, then proceed as follows:
Figure 19. Gas Manual Valves.
a.Turn off main electrical switch.
b.Turn off all manual gas valves and wait five minutes (see Figure 19).
c.Set operating control to lowest setting.
d.Slowly turn manual gas valve to “ON”.
e.Reset all safety valve switches (manual reset high limit and low water cut off).
f.Open manual pilot valve. Turn on main electrical switch.
g.Set temperature controller to desired temperature. Pilot will light automatically to ignite main burners whenever the aquastat calls for heat.
For standing pilot system, press on pilot relay knob, see Figure 20, light pilot and keep relay knob
Figure 20. Pilot Safety Relay.
