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 |
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button on manual reset limit |
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switch. UHD 100 - 125: Wait |
| Fan and limit switch are |
10 - 15 minutes for limit | Yes | operating normally. |
switch to cool. Does fan |
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stop running? |
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No |
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Replace temperature limit |
|
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switch. |
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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? |
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| |
To test valve, See | No | Replace valve. | |
Troubleshooting for Gas | |||
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Valves section. |
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| |
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
For optimum heater performance, use only replacement parts sold and supplied by
Conduct start-up procedure as shown on Page 23, Section 10.
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