AG2
Series
53
Check to make sure gas pressure is within minimum and
maximum inputs, as indicated on heater’s rating plate.
Is gas pressure OK?
Were the gas lines purged of air?
Is the heater properly
grounded? Is the heater’s
polarity correct?
With microampmeter, check DC
voltage at flame rod. Is it greater
than .05 microamps?
Check to make sure flame
sensor wire is OK and then
replace circuit.
Sensing rod is faulty or flame is weak.
Check to make sure heater is operating
at proper gas pressure as indicated on
heater’s rating plate and then, if
needed, replace sensing rod.
Replace gas valve.
Yes
Correct problem.
Correct problem.
No
No
Yes
Yes
No
Yes
Purge gas line.
No
Is there 24V across the GROUND and HIGH
(HIGH to COM on heaters with optional
HLRB relay) on the terminal strip located on
the outside of the control box?
Repair or replace faulty
wiring or thermostat.
Replace relay.
No
If heater does not go into high fire mode:
Measure voltage across the red wire
on the VALVE and GROUND (red wire
on RELAY to GROUND on heaters with
HLRB relay). Is it 24V?
Yes
No
Yes
Replace gas valve.
NOTE
: To confirm that the heater is not in high fire mode, check manifold pressure. If manifold
pressure is 3.3 to 3.5 inches W.C. for natural gas or 9 to 10 inches W.C. for propane, the light is faulty
and should be replaced.
When the heater is in low fire mode, manifold pressure is approximately 2.0 to 2.5 inches for natural
gas or 5.0 to 6.5 inches for propane. If this is the case, the following troubleshooting steps should be
followed:
5.0
Troubleshooting Guide
