Heat N Glo Townsend fireplace won't light


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Old 02-25-17, 12:15 PM
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Heat N Glo Townsend fireplace won't light

We have had this for awhile, over 15 years without a problem.
Back story is probably unrelated, the city replaced our gas meter recently, and this was the farthest from the meter so he had me light this unit first, but again worked fine, the meter guy was happy it lit without a problem (I guess you get air in the gas lines and can make things a chore to relight).
Anyways, a week or so ago my wife went to light it, and it wouldn't light.
I went down, tried it myself, and no luck either, I did trying to move the hi-lo knob and then it suddenly decided to light, could be a coincidence.
She lit it this afternoon without a problem, then a undetermined amount of time later she noticed it was out. Now refusing to light again. This is a standing pilot system and the pilot has remained operating. I am kind of a dummy on these right now, I could hire the installer to come look at it. Looking over the info that came with the unit I am looking at maybe the thermopile, is this what keeps the flame going once it is lit? I know there is a thermocouple as well but I think this is for the pilot, correct? If it cools down the thermocouple is what shuts the gas off? Any guidance appreciated. Gas valve (on the supply line to the unit) is off for now for safety.
 
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Old 02-25-17, 01:18 PM
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The thermocouple holds the pilot valve open when heated.
The thermopile or pilot generator supplies the power to open the main valve.

Both require a large bushy looking pilot light.
The thermocouple and thermopile are both heated by the pilot.

If the pilot doesn't look big and healthy.... you more than likely have a partially plugged pilot light orifice.
 
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Old 02-25-17, 05:03 PM
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I would describe the pilot light as looking normal, like it always has.
Also, I can see the point about the pilot light size if the problem simply was not lighting, but now it has gone out on us once too, is the pilot lights job done once the flame is lit? I guess I am looking at the thermopile. I did see something in the troubleshooting part about the thermopile having a certain millivolt it is supposed to put out. Does the thermopile degrade with time? I have a VOM I can measure with.
 
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Old 02-25-17, 05:15 PM
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The thermocouple holds the pilot valve open when heated. It is connected to the gas valve with a threaded fitting and is pretty hard to test.

The thermopile or pilot generator supplies the power to open the main valve. If you have a problem with the pilot occasionally going out and intermittent burned operation.... you have a pilot flame issue.

The pilot generator is part of a millivolt system. You can check the output for DC volts. It should be roughly 500 millivolts (1/2V) with the gas valve off. With the fireplace calling for heat that will go down to around 400mv. The exact voltages are in the manual. The generator connects directly to the mv or PG contacts on the gas valve.

Both devices can degrade with time and heat but you are having a problem where both have a problem. Pretty rare for both to go bad at the same time.
 
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Old 02-25-17, 05:33 PM
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The pilot light is NOT going out, the flame itself (the big one, the reason you have a fireplace), is what is going out.
When I say she went down to light it, I mean she flipped the switch on the back of the unit to get some heat)
 
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Old 02-25-17, 07:15 PM
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I can see the point about the pilot light size if the problem simply was not lighting, but now it has gone out on us once too, is the pilot lights job done once the flame is lit?
Did I misread this ??


In the following picture..... I've highlighted the pilot generator. With the stat or burner switch off..... measure that DC voltage. It will be under 1 volt. It will be in millivolts.
What do you get ?

Now turn the switch on and measure it again. Now what do you have ?

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Old 02-26-17, 01:51 AM
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Yes, I think when I said "she went down to light it", maybe you thought I meant to light the pilot. She just went down and flipped the switch to get some heat is what I meant, the pilot was ON, the pilot has never gone out.
I am suspecting the thermopile, is that the pilot Generator millivolt system? I have the owners manual which discusses testing too.
I don't know about trying to clean it but I think that's the direction I am heading. I will do those tests later today, heading off to work now. Thanks.
 
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Old 02-26-17, 08:43 AM
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The pilot generator, like in the picture, has an armored cable so it's wires are easy to spot.
The generator doesn't get cleaned.
 
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Old 02-26-17, 02:19 PM
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Pete
Seems to be all correct. In the manual, with the on/off switch off it should be 325mv minimum, I get more like 560mv.
With it on it should be over 100mv, at first I had 206mv, slowly dropped to around 185mv or even a little lower, may have dropped to 175mv or so? But never down to 100mv. It was lighting for me too, seems really sporadic. I might need to call in an expert. Not ready give up now. I have a nice Fluke meter from when I worked on cars, I have the alligator clips left on the red and white wires so I can test at random times. So mainly I need to switch on the meter and see what the voltage is (over 325), switch it on and should be over 100mv. If that is all correct and it is not lighting it would point at the valve? Is that something I can do myself if I feel comfortable with it or should I call an expert?
Thanks a lot.
Gilly
 
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Old 02-26-17, 02:24 PM
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PS there are 2 BLACK wires which I believe go to the thermoCOUPLE, again this I don't think relates to my problem, as I believe that is only for the pilot light. I just see a little discrepancy in terminology, all I have is what the manual discusses, which is thermopile (which affect the main flame) and the thermocouple, which only affects the pilot light. I think I have it narrowed to the thermopile or the gas valve. In one test, and this was when I first started and the main flame didn't feel like lighting, I jumped the red and white wire and nothing happened, I believe jumping the red and white should have resulted in a start of the main flame. Then I flipped the switch and lo and behold the flame then lit.
I can take pictures of the valve if you'd like. Looks similar to the picture you posted.
 
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Old 02-26-17, 03:47 PM
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The picture I posted is directly from Heat-n-Glo tech services.

In the picture you can distinctly see the two cables. Are you saying that your heater doesn't use the armored type cable on the thermopile but two black wires instead ?

That would be rare because the wiring to the thermopile is right next to the flame and standard wiring would melt.

Maybe a picture would be good. http://www.doityourself.com/forum/el...-pictures.html
 
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Old 02-26-17, 04:10 PM
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Pics inserted.
Sorry I misunderstood the thermocouple has no wires.
The black wires go to the switch. (I'm sure you knew all this)
The red and white wires, correct the go in to a shield, I have shown on pics and am pointing at the shielding.
You can see my Fluke is connected, I will try lighting it occasioanlly and see if I get a fail, I can monitor the voltage.
 
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