Ignition Issues w/ Heatilator Gas Fireplace

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.


New Member
Aug 19, 2018

I have an older Heatilator Gas Fireplace, Model GC340E, with a B-vent. It was installed in 1991.

I have never used the fireplace that much and several years back I heard some buzzing noises right after turning the wall switch on. Along with the buzzing I could hear the typical clicks that come when the spark igniter is on. After 8 seconds or so I turned it off because not even the pilot would light. I have recently tried to troubleshoot the issue. This time, about 6 weeks ago, when I hit the switch, the spark igniter clicked as normal without the buzzing noises, but clicked for a long time before the pilot lit (about 10 seconds). After about 20 seconds more the main burner never lit and I decided to turn it off. I decided to bring in a tech guy from a local company that reps Heatilator for help. He checked out and 1st cleaned the flame sensor hoping that was it. That did not work, but the flame sensor was glowing red so he though it should be reading fine. He suggested replacing the following: 1) Transformer 2) Ignition Control Module and 3) Pilot Assembly {Pilot, Spark Igniter, Flame Sensor}. Since Heatilator does not stock parts for this model any more, the tech could not order the parts but told me I could find them online. I did purchase the same parts as the originals are specified and I decided just to connect the transformer and the Ignition Control Module to see what would happen. This time the Spark Igniter clicked 3 times and then nothing! So now I'm worse than before. I decided to invest further by buying a digital multi-meter. I have the following:

1) I'm measuring 124 VAC to the transformer.
2) I'm measuring 27 VAC to the Ignition Control Module (Robert Shaw Model SP735A) I measured between Terminals TH and TR.
Perhaps the multi-meter is off a bit, but regardless I think I'm still within spec. Also, I believe the High Limit Switch is OK, since I have voltage going to the ICM.

I understand that the Robert Shaw ICM Model SP735A has issues and did see that Robert Shaw makes a replacement which is Model 780-745. Does anyone know if it is worth trying the newer model, if determined that the ICM SP735A is a dud? Is the newer Robert Shaw Model compatible with the Robert Shaw Gas Valve Model 7100DER.

Also, can anyone guide me as to how to check if power is getting to the Igniter, Pilot Valve, Main Valve, and Flame Sensor?

Should I be checking for amps and watts (VA)?

Is there any reason to replace the Pilot Assembly before re-testing?

Am I missing anything?
I've attached the Schematic from the Heatilator IOM Manual for reference.

If you got to this point, I thank you for reading through this. Sorry for the length of this post, but I wanted to get in as must detail as possible up front to avoid a lot a back and forth replies.

Any constructive thoughts and/or comments would be appreciated as replacing this fireplace would cost about 15 more than I already invested. So even if I have to spend a bit more it will be worth it if I can get this old unit up and running again.

Best Regards!


  • Heat GC340E Schematic001.pdf
    56.1 KB · Views: 362
Since the pilot lit, at least initially, you have gas to the pilot hood.
Have you pulled the burner off & checked behind the burner orifice for a blockage?