Heat N Glo SL-750TV-D Main Burner Not Lighting

[Alexjordan22]

We bought this house about 3 years ago and the fireplace has always worked fine. The pilot light is lit, but when I flip the wall switch it no longer fires up.

I do have a small green wire that has been stripped but is not attached to anything. It has worked like that in the past but I'm not sure why it's like that.

I have a multimeter but am unsure of which wires to check. I have seen suggestions of jumping two wires together also to rule out certain parts but don't want to guess about what I'm doing. Any help would be appreciated!

 

[DAKSY]

Set your meter to vDC .. Take a reading on the TP & TH-TP terminals with the pilot lit, & the power switch off. Tell us what you get

 

[Alexjordan22]

Set your meter to vDC .. Take a reading on the TP & TH-TP terminals with the pilot lit, & the power switch off. Tell us what you get

.553 V

 

[DAKSY]

.553 is almost ideal. Turn the switch on. Watch the voltage. What reading are you getting? Should go to about .220…

 

[Alexjordan22]

.553 is almost ideal. Turn the switch on. Watch the voltage. What reading are you getting? Should go to about .220…

Okay, with the switch on im reading .413 V

 

[DAKSY]

That’s WAY too high. Can you hear the valve “click” open when you hit the switch?

 

[Alexjordan22]

That’s WAY too high. Can you hear the valve “click” open when you hit the switch?

No, I don't hear anything happening when I turn the switch on.

 

[DAKSY]

Try jumping the TH & TH-TP terminals with a wire or a paper clip. What happens?

 

[Alexjordan22]

Try jumping the TH & TH-TP terminals with a wire or a paper clip. What happens?

If I jump those terminals I hear a click and it lights right up

 

[DAKSY]

Switch is probably bad. Test it by pulling it from the wall, disconnecting the wires & jumping them. If the unit fires, it’s the switch. If it doesn’t, it’s the wiring.

 

[Alexjordan22]

Switch is probably bad. Test it by pulling it from the wall, disconnecting the wires & jumping them. If the unit fires, it’s the switch. If it doesn’t, it’s the wiring.

I appreciate your help with this! I'll test the switch today and will follow up if that was the issue or not

 

[Millbilly]

If that green wire goes to the switch, it needs to connect to the valve. I'm pretty sure that's your problem.

 

[Alexjordan22]

Switch is probably bad. Test it by pulling it from the wall, disconnecting the wires & jumping them. If the unit fires, it’s the switch. If it doesn’t, it’s the wiring.

If I jump the wires together it fires up. I think you're right about the switch - it seems like an intermittent problem and sometimes it works and sometimes it won't. I'm going to replace the switch.

 

[Lennox65]

If that green wire goes to the switch, it needs to connect to the valve. I'm pretty sure that's your problem.

The green wire is part of the original switch wire that HeatnGlo uses. For most fireplaces, only the red and white wires are used and the green is left unused. This model fireplace does not use the green wire.

 

[Alexjordan22]

I removed the switch cover and the switch appears to be working. If I test for continuity with the switch off there is no continuity between the contacts. If I turn the switch on then I have continuity so it appears to be working.

Still, if I jump the contacts then the fireplace fires up just fine. I guess I'll inspect the wiring and verify continuity from the switch to the fireplace because I'm not sure what else it would be.

 

[Lennox65]

I removed the switch cover and the switch appears to be working. If I test for continuity with the switch off there is no continuity between the contacts. If I turn the switch on then I have continuity so it appears to be working.

Still, if I jump the contacts then the fireplace fires up just fine. I guess I'll inspect the wiring and verify continuity from the switch to the fireplace because I'm not sure what else it would be.

Have you tried disconnecting the switch wires from the wall switch and putting them together? If you do this and the fireplace lights and stays lit, (I would try it a few different times) then the problem is the switch. Just replace it.

 

[Millbilly]

After reviewing your photos you have a limit switch in the circuit. It's either a limit switch or a glass closed switch. Either way that is your problem. One end is attached to the top terminal. The other should be attached to your red wire. Follow that wire, turn your switch on, and then jump at the safety switch. Just do this diagnostically. If it turns on replace the switch, do not leave it jumped as it is a safety device.