AAON M2-036 - Manual (Page 61)

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For On-Off units the manifold pressure
should be 3.5” w.c.
Failure to Ignite
1. For the initial start-up, or after unit has
been off long periods of time, the first
ignition trial may be unsuccessful due to
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 to 90 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. Some
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 flame. See
Figure 34a and Figure 34b for flame
characteristics of properly adjusted natural
gas systems.
Figure 25 - 1.2” w.c. Manifold
Figure 26 - 3.5” w.c. Manifold
1. The burner flame should be
predominately blue in color and well defined
and centered at the tube entry as shown in
Figure 34a and Figure 34b. Distorted flame
or yellow tipping of natural gas flame, or a
long yellow flame on propane, may be
caused by lint and dirt accumulation inside
burner or at burner ports, at air inlet between