Thernal Coupler change - Gas Fireplace
 

The other night I noticed the pilot light on one of my gas fireplaces was out. I followed the instructions to restart it but not only would the igniter not light the pilot but even if I lit it with an open flame, it would not stay lit. I tried cleaning it with a wire brush and such but no good. At this point I am assuming it's the thermal coupler that is bad. I read how easy it was to change these but when I went to remove it, closer inspection seems to reveal that the coupler is riveted to the pilot assembly.

Does this mean I need to replace the entire assembly or did I miss something?

http://avn.net/wc_house/pics/thermal_coupler.JPG

Thank you!

You are calling the coupler the 1/2 inch round part on the far right side of your pic.? Was the sparker sparking When you tried to lite it?
Where the pilot line ties to the pilot assembly, if you take the pilot line off there is a orifice in there that has a very small hole in it that might have to be cleaned out. When the flame is lite you should have a blue flame that comes out around the thermocouple about 1/2". Does you coupler have wires coming
from it, if so it is called a power pile. That sparker need to be cleaned with emery cloth or sand paper. Later Paul

Hi Paul,

Yes, going by this diagram I saw http://www.sutterhearth.com/media/valvecrosssection.jpg I assumed he thermal coupler was the white tube with the metal "probe" sticking out of it.

Yes, I can see a small blue spark when I push the ignite button but the pilot doesn't light. If I use a cigarette lighter the pilot will light but will not stay on, even after 1 or 2 minutes of holding the pilot adjuster knob in.

I also found this diagram below which is not exactly what my pilot looks like but I now get an idea of where the cleaning hole is ... Is this what you are talking about:

http://sites.google.com/site/sublime...ecrets/ODS.bmp

I will take the assembly off tonight and clean it and update to whether that fixed the problem or not.

Thank you!

Yes there is a small orifice and the hole is very small. There may be a air way going in around this orifice. that also gets plugged up. That power pile need a good sharp blue flame going around it. Check all wires to make sure they are clean and tight. If your pilot is burning right and it won't stay lite than it would be ether a bad power pile, bad set of contacts or the magnet in the gas valve is too weak.
Later Paul

Ok so i disconnected the gas line to the pilot and I have this updated photo below. According to some install instructions it looks like I have a thermopile not a thermo coupler. I checked over and over again and there is no small hole to be cleaned anywhere that I can see. I used some sandpaper to clean the pilot hood and thermopile but the pilot doesn't seem to stay lit although the ignitor is working again.

I guess I need to change the thermopile?

http://avn.net/wc_house/pics/thermopile.JPG

You never did tell me if you have a good blue pilot flame that goes around the power pile
about 1/2" down from the top and around the power pile. If you do then your pilot doesn't need cleaning. If you have a lazy yellow flame then it will not heat up the power pile enough to make any power.
When you took off the pilot gas line, the orifice with the small hole is up inside the pilot where you took off the pilot line. But those orifices are hard to get out and if you have a good pilot flame then your ok.
You would have to have the power pile power tested to see if it needs replacing.
At your gas valve , take off your thermostat wires but leave the power pile wires on then lite the pilot and see if it stays on. If you can't electrical test the power pile then i guess you could just replace it. You would have to test millivolts to test it. Later Paul

Hi Paul,

Yes, the flame is big an blue. I don't have an ohms meeter so I cant test the thermopile. I looked on the 'net for the manufacturer of my fireplace (Superior) and they only have one safety type doc with that model number on it and nothing else. Can I just purchase and after market one if I make sure its the same length and millivolts?

Thanks again for all your help!

Yes you can just buy a power pile at any heating whole sale house. The length is not important but the millivolt power is. It has been my experience that the cheep one don't work as good, so i have always bought Honeywell. They may cost more but the work better, and give you more power. Later Paul

Hi Paul,

I went and picked up a new Honey Well thermopile for $56. It is the same size and milivolts as the one I replaced. I put it in and lit the pilot manually and held the button for about two minutes and the pilot still doesnt stay lit. There are two wires going to the thermosat and i disconnected both of them but still left power pile leads on and the pilot still doesnt stay lit either. Below is a photo of what it looks like...

http://avn.net/wc_house/pics/fireplace.jpg

Do you have any idea of what I should try next?

pilot flame
 

Hi Paul,

I also took this video of the pilot flame:


Pilot Flame Video


Does the flame look good?