Can't find thermocouple for Superior logs

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unorthodoxcreations

New Member
Jan 23, 2023
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I have Superior logs model vfgl-18msp in the house we bought last year that run on propane. They will light but not stay running very long. I believe it needs a thermocouple but I can't find one that fits. I've found the parts diagram but it seems to list every part but that. Ive bought a universal one from Lowe's and one from Amazon but both have the wrong threads at the end. My threads are coarser than what I have. Any suggestions on how to fix this?
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I have Superior logs model vfgl-18msp in the house we bought last year that run on propane. They will light but not stay running very long. I believe it needs a thermocouple but I can't find one that fits. I've found the parts diagram but it seems to list every part but that. Ive bought a universal one from Lowe's and one from Amazon but both have the wrong threads at the end. My threads are coarser than what I have. Any suggestions on how to fix this?View attachment 308338View attachment 308339View attachment 308340
<a href="https://www.manualslib.com/manual/481828/Superior-Standard-Series.html?page=16">Replacement Parts List - Superior STANDARD SERIES Installation And Operating Instructions Manual [Page 16]</a>
If this is the manual for your log set, I don't see a thermocouple listed. Ventfree log sets typically only have thermopiles.
 
I have ran across thermocouples like that in the field. Post a picture of your pilot assembly. Vent free logs have thermocouples but they are welded onto the pilot tube. Even though you aren't supposed to modify a unit, if it were me, I would buy a complete pilot assembly with the welded on thermocouple and replace the whole thing. The assembly could be a different size though.
 
The setup is ventless. Here is a picture of the pilot assembly loosely in place.
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Here is where the thermocouple screws in.
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Honestly I haven't really done any testing. I had just fixed our hot water heater that was occasionally going out with a new thermocouple. I thought the fireplace would be a similar easy fix but I've bought 2 thermocouples and neither fit. The tips have been different but could probably be made to work but the threads on the other end are different.
 
I can't tell you for sure this one will fit with the extra rib toward the bottom. It is all according to how the mount is.

That does look like it has the coarser threads I need compared to what I've gotten from Lowe's.
 
I purchased the pilot assembly because it was pretty much the same price as the thermocouple from Home Depot but I could get it faster. It was slightly different in construction but bolt right up with no modifications and that fixed my problem. Fireplace now starts and stays running with no problems.
 
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