Roberts Gorden 75 User Manual

35 of 47

Ensure air flow through the 

heat exchanger is 

appropriate per the rating 

plate.

If problems persist, contact

Roberts-Gordon LLC at

www.rg-inc.com

Heater Operating

No

Replace limit switch.

The limit switch has 

tripped. See Manual Reset 

Limit Switch section.

No

Use Troubleshooting for

Automatic Ignition Burner

Systems section to test burner.

Has burner “Locked Out”?

Yes

No

With external controls (i.e. 

thermostat) on, does the 

burner continue through the 

heating cycle?

No

Yes

Does the flue blower run?

No

Use Troubleshooting for 

Flue Blower section to test 

fan.

Yes

Yes

Burner has locked out due 

to ignition failure. Use 

Troubleshooting for Automatic 

Ignition Burner Systems 

section to test burner.

Is ignition control showing a 

"2 flashes" LED code?

Yes

No

Yes

Fan and limit switch are 

operating normally.

Replace temperature limit 

switch.

UHD 75: Press in reset 

button on manual reset limit 

switch. UHD 100 - 125: Wait 

10 - 15 minutes for limit 

switch to cool. Does fan 

stop running?

No

Is ignition control showing a 

"4 flashes" LED code?

Yes

No

Yes

Turn on supplies.

Are gas & electrical

supplies on?

No 

Yes