Williams Vented Room Heater 3501522A will not ignite main

moths_prowess

Hi all,

I'm a homeowner who had a garage furnace installed maybe 5-6 years ago. It has never really worked properly, never igniting at the right time even when it's freezing cold. I kind of put up with it for a while because I really didn't like the installer. I tried fixing it a few years ago and managed to do so by bypassing the vent safety switch with an alligator clip which would allow it to come on. But last year that stopped working too. I'm determined to get this working though, at least if it costs less than just replacing it with an electric one. My main problem has never being able to find any sort of help on the internet for how to fix this, mostly because the manual doesn't once in the entire manual refer to the thermopile as a thermopile, it calls it a generator. A few weeks ago I found a video and it called it a thermopile. and then I found this forum today!

anyway

This time around I thought it was the thermopile because I measured at the terminals per the manual and it read at 400mv, so I ordered several new thermopiles and lo and behold those also didn't work. I have been laying on the garage floor for hours testing out different things according to the troubleshooting guide in the manual and then finally found this forum after more searching. I have read over several threads about thermopile systems vs thermocouple systems and that thermopile is different than powerpile and I've also looked over the manual. https://heatinghelp.com/assets/documents/Procedures-for-Troubleshooting-Powerpile-Systems2.pdf

I went through and took measurements for everything except pull in, I do not understand how to do this at all, especially since the burner won't light at all.

Measurement	mv	notes
Open circuit	750	tested with all three of the thermopiles I have now
Closed Circuit (per manual, meaning thermostat wires disconnected, but thermopile wires connected to valve body)	417	consistent, but goes down if I change flow rate grub screw
Closed Circuit Thermostat Jumped	157	consistent
Measurement at thermostat with thermostat disconnected	417	0 mv drop across wire (thermostat wire is only about 10ft long) I do not understand the difference between this and Limit though
Drop out	67

I also took a video showing the clicking when jumping the terminals, but apparently I can't upload a video.

Oh and here's the troubleshooting page. Not very helpful.

moths_prowess

Oh and here's the troubleshooting page.. it's pretty useless so far.

EBEBRATT-Ed

Try this.

You should only cautiously jump safeties when you are testing. Don't leave any unit running with any safety jumped. You mentioned jumping the vent switch. Bad move

POWERPILE INFORMATION.pdf

moths_prowess

Hi Ed, that's the same troubleshooting guide I linked in my initial post above. I followed that exact guide and posted the results. I'm out of ideas and the pdf doesn't say what to do if none of that works. And also like I said, I do not know how to test pull in if the furnace will not light.

And yes, I understand the safety jump was dangerous, but the furnace didn't function at all without it. I have an MSA gas monitor and many many CO monitors so I was monitoring for danger (when it was working).

mattmia2

might be time to measure the manifold and line pressures.

is there a safety valve that has to be reset when the pilot generator/power pile/ thermopile has cooled?