Service manual

ROBERTS-GORDON SECTION 13: TROUBLESHOOTING pg 39
Do burners shut off after the
call for heat is satisfied?
Make sure that all
thermostats (including
SmartSet and Night Set
Back) are established.
With the thermostats connected, measure
the voltage between the thermostat terminals
(T1, T2, T3, T4, SCT and NST) and the
COM terminal. Are all the voltages 5V.
Replace main control board.
(P/N 90437500)
Check thermostat wiring for
shorts and replace thermostat
if necessary.
Does the pump shut down
after a 45 second post-purge
period?
Make sure that all thermostats
(including SmartSet and
Night Set Back) are satisfied.
Disconnect all thermostat wires
from COM. Does the pump
continue to run after a 45 sec.
post-purge period?
Reconnect thermostat
wires. Disconnect W1 wire
from pump relay. Does the
pump still run?
Replace pump relay.
(P/N 90437900, Omron G4B-
112T1-US, or equivalent)
Troubleshoot ends.
If problem persists, contact your
local Roberts-Gordon
Representative.
Check thermostat wiring for
shorts and replace thermostat
if necessary.
Replace main control board.
(P/N 90437500)
No Yes Yes
No Yes Yes Yes
No No NoYes
Yes Yes
Is the continuity of the earth
wire established?
Is the insulation on the
igniter/sensor leads OK?
Ignition module may have
failed. Replace module.
(P/N 90434002K)
Yes Yes
No No
Check for the proper orifice and
air plate inside the burner.
Adjust the valve pressure.
Is the gas outlet pressure
3.5" for Natural Gas
(10.5" for LP)?
Purge Lines.
Is there gas outlet pressure available during the ignition
period?
Measure voltage on valve
terminals. Is there 24V
during ignition period?
Replace gas valve.
(Natural P/N 90032500)
(LP P/N 90032502)
Is the knob on the gas
valve in the on position.
Are the wires connecting the
ignition module OK?
Turn valve on.
No No
Yes Yes
Yes
No
Yes
Yes
NoNoNo
YesNo
Yes
Replace ignition module.
(P/N 90434002K)
Were the gas lines
purged of air?
Is the inlet gas pressure during
ignition correct? (Natural 4.6"
min, 5.0 for EV-175, -200,
LP should be 11.0" min)
Replace door.
Does the burner light?
Check gas line stop cock.
Contact gas company.
Replace ignition module.
(P/N 90434002K)
Replace/Correct wires.
Yes
No
Does the burner stay on?
Re-Establish Continuity. Re-Establish Continuity.
Do all the burners
ignite smoothly?
Is the vacuum setting
to high?
Adjust system for proper
vacuum. See page 36 for
details.
No No Yes
Yes
Yes
Yes