30
Figure 22 – White Rodgers 36H55 Gas Valve
Failure to Ignite
1. On the initial start-up, or after unit has been off long periods of time, the first ignition trial may be unsuccessful due to the
need to purge air from manifold at start-up.
2. If ignition does not occur on the first trial, the gas and spark are shut-off by the ignition control and the control enters an
inter-purge period of 15 seconds, during which the draft inducer continues to run.
3. At the end of the inter-purge period, another trial for ignition will be initiated.
4. Control will initiate up to three ignition trials on a call for heat before lockout of control occurs.
5. Control can be brought out of lockout by turning thermostat or controller to its lowest position and waiting 5 seconds and
then turning back up to call for heat. Controls provided will automatically reset after one hour and initiate a call for heat.
Burner Flames
Prior to completing the start-up, check the appearance of the main burner flames. See Figures 23 A and B below for flame
characteristics of properly adjusted Natural gas systems.
Figure 23A
Figure 23B
Burner Flame @ Start-up 1.0 to 1.2” w.c.
Manifold Pressure Draft Inducer – High Speed
Burner Flame @ High Fire 3.5” w.c. Manifold
Pressure Draft Inducer – High Speed
