Roberts Gorden UHD[X][S][R] 75, UHD[X][S][R] 125 service manual TROUBLESHOOT ENDS. No

UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL

13.2Troubleshooting For Automatic Ignition Burner Systems

START

Are gas & electrical

supplies on?

Yes

Are external controls (i.e. Thermostat) on?

Yes

Is ignition control showing a

"4 flashes" LED code?

No

No

Yes

Turn on supplies.

Turn on controls.

UHD 75: Press in reset
button on manual reset limit
switch. UHD 100 - 125: Wait		Fan and limit switch are
10 - 15 minutes for limit	Yes	operating normally.
switch to cool. Does fan
stop running?
No
Replace temperature limit
switch.

No

Does flue blower run? No

Yes

Does air pressure switch

Is 120 V supply at fan	Yes	Flue blower faulty;
connections?		replace

No

Burner control faulty or wiring

connections faulty. Repair

or replace as required

Check for too much vent/air inlet duct. Check for blockage in vent and combustion air circuit. Check for faulty air pressure

change over?

Yes

No

switch. Check pressure switch hoses for leaks or cracks. Do not attempt to circumvent pressure switch circuit to

place unit in operation.See Pressure Switch section for details.

Wait 30 - 40 seconds.

Does ignition spark No operate?

Yes

Does the flame light? No

Yes

Is ignition control showing

a "2 flashes" LED code? Yes

No

Heater Operating

TROUBLESHOOT ENDS. No

Is ignition lead okay and	Yes	Ignition control faulty;
connected?		replace.
Is spark electrode okay?		See Ignition Control section.
Is the gas valve operating?
To test valve, See	No	Replace valve.
Troubleshooting for Gas
Valves section.
Is the flame current at		Trace fault in supervision
least 1 μAmp DC when	Yes	system. See
the flame ignites?		Troubleshooting

for Flame Supervision

System section.

If problems persist, contact

Roberts-Gordon LLC at

www.rg-inc.com

For optimum heater performance, use only replacement parts sold and supplied by Roberts-Gordon.

Conduct start-up procedure as shown on Page 23, Section 10.

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