# Pilot on Williams millivolt wall heater goes out every 8 to 16 hours



## Yoyizit (Jul 11, 2008)

Post a schematic if you have one. These kinds of problems have something to teach.


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## wornways (Dec 10, 2009)

Yoyizit said:


> Post a schematic if you have one. These kinds of problems have something to teach.


Hi Yoyizit,

I would love to post a schematic. But I don't know if I have one. Is it something that would be on or in the heater itself somewhere? I can also take detailed pictures of the heater and the thermostat and post them if this would be useful to you and other readers.

Thanks, and take care,

-----Erin


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## kennzz05 (Nov 11, 2008)

has anyone cleaned the pilot oriface if the pilot flame isnt strong enough the burning flame will cause increased draft thru the heat exchanger and pull the pilot away from the tpile and cause it to go out my vote is on cleaning the pilot and verifying a good strong flame that totally engulfs the thermopile


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## wornways (Dec 10, 2009)

kennzz05 said:


> has anyone cleaned the pilot oriface if the pilot flame isnt strong enough the burning flame will cause increased draft thru the heat exchanger and pull the pilot away from the tpile and cause it to go out my vote is on cleaning the pilot and verifying a good strong flame that totally engulfs the thermopile


Hi Ken,

All check. Throughout the whole ordeal described in my original post, the pilot flame has always been very strong and has always engulfed the thermopile without so much as a flicker.

In fact, the second repair man gave the heater a thorough checking over. He said the pilot assembly was very clean, but he removed just a small bit of carbon that had collected inside anyway.

I have one more piece of new information to add. With the original gas valve I often had to stomp on the floor or thump the wall next to the heater in order to get it to turn on once the thermostat engaged. With the second gas valve this was no longer the case. However I just discovered with this third gas valve, installed only yesterday, that I once again have to stomp on the floor or thump the wall next to the heater in order to get it to turn on once the thermostat has engaged. So, it looks like I'm back to the same behavior that was occurring with the original gas valve.

Later tonight I'll take pictures of the heater, the thermostat, the pilot flame, the active burner, and the gas valve, anything I can, and post them here. Maybe someone will see some clue in the photos.

It's been about 14 hours since I last lit the pilot, so we're getting near time for another outage.


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## kennzz05 (Nov 11, 2008)

the stomping/hitting the wall thing could be a broken tstat wire or nearly broken id try just for giggles running a piece of wire outside of the wall and put the stat on a table or something just to see if it makes any differance


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## beenthere (Oct 11, 2008)

You may have already done this. But if you haven't.

Physically trace the thermostat wire back to the gas valve. There may be a limit switch that you are unaware of.

I say this because you said you sometimes have to stomp near the furnace to get it to turn on.

Next. On units with a bad limit(same can happen with no limit). They tend to over heat causing too much draft. And at the end of the cycle when they turn off. The excess draft can draw the flame too far off pilot and cause it to go out.

Pics will help.


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## wornways (Dec 10, 2009)

beenthere said:


> Physically trace the thermostat wire back to the gas valve. There may be a limit switch that you are unaware of.
> 
> Next. On units with a bad limit(same can happen with no limit). They tend to over heat causing too much draft. And at the end of the cycle when they turn off. The excess draft can draw the flame too far off pilot and cause it to go out.
> 
> Pics will help.


Hi beenthere,

Appreciate your input. Thank you. Here's what I know in relation:

If there is a limit switch anywhere, it would have to be inside the wall next to or behind the heater. I can only trace the wire about four inches back and up and then it's gone. Both repairmen who have been here to deal with this heater have commented on the lack of a limiter switch. So I'm feeling pretty sure there isn't one. Still, have you ever heard of cases where limiter switches were installed inside the wall near or behind the heater?

I have observed the pilot going out about a minute after the heater has been on and just before it would normally turn on. It's possible that the pilot has gone out at the end of the heat cycle, but I don't think so because I've developed a habit of checking the pilot, and when it's not out, it's usually on between cycles, and out just before or during a heat cycle. Still, this is worth my bearing in mind. So I'll watch for it.




kennzz05 said:


> the stomping/hitting the wall thing could be a broken tstat wire or nearly broken id try just for giggles running a piece of wire outside of the wall and put the stat on a table or something just to see if it makes any differance


Hi Ken,

This struck me as a good idea. Since the old thermostat is still around that was replaced with the other old thermostat from another unit, I've dug through my things for some wire and I've hooked up the old thermostat to the heater. It's sitting about three feet away on the other side of a wall from the heater. That might sound impossible, but the heater is just next to a door frame.

Before I post the pictures I took before, I'll see how long it takes the pilot to go out using this configuration.

What's interesting is that when I took pictures of the gas valve, I pinched the thermostat wire to the side in order to give me a clear shot of the label on top of the gas valve. The heater then went for another 28 hours without the pilot going out. Altogether the pilot stayed lit for just over 40 hours, which is the longest it's stayed lit in over two months. I have to wonder if pinching the wire did anything. Later when the heater didn't turn on, stomping on the floor or thumping the wall by the heater had no effect. However, when I thumped the wall by the thermostat, then it went on. How strange is that? Is it possible the thermostat wire is cracked in more than one location? It seems to be every bit as old as this house, and let me tell you something--I think this house has been here since about when our city of Ukiah, CA was founded.

Will report back again next time the pilot goes out. If it doesn't go out in the next few days, then I'll report back with that information and contact the repairman with the info. I'd love for there to actually be a solution.

But, tell me, do you think it's possible for a cracked thermostat wire to somehow cause the pilot to go out? If so, would it have something to do with static electric build-up along or near the wire and a strong enough discharge that could cause the gas valve to close all valves, including the pilot?


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## Livewire78 (Dec 6, 2009)

I've seen this happen before and this is gonna sound crazy but, its possible that the thermopile is not close enough to the pilot flame, the metal support they rest on may be thin enough that you can hand bend the thermopile a little closer to the flame. Like I said seen it happen before, just a little closer may make all the difference. Its worth a shot. I've learned that sometimes its the simpliest things that everyone oversights


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## log_doc_rob (Sep 5, 2009)

If you have a multi-meter, check the voltage of the thermopile with the main burners on and off, these readings will be different and report back. I would think there is a problem with the pilot not properly heating the thermopile due to pilot being too small or pilot being improperly adjusted so it is not heating the tip of the thermopile.


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## wornways (Dec 10, 2009)

Livewire78 said:


> I've seen this happen before and this is gonna sound crazy but, its possible that the thermopile is not close enough to the pilot flame, the metal support they rest on may be thin enough that you can hand bend the thermopile a little closer to the flame. Like I said seen it happen before, just a little closer may make all the difference. Its worth a shot. I've learned that sometimes its the simpliest things that everyone oversights


Hi Livewire,

This is a good call, but I and the repairmen have already tried about every permutation of moving the thermopile closer to or farther from the pilot and increasing or decreasing the strength of the pilot flame. In every case, the thermopile has been completely surrounded by a sturdy flame and the tip covered by the flame.



log_doc_rob said:


> If you have a multi-meter, check the voltage of the thermopile with the main burners on and off, these readings will be different and report back. I would think there is a problem with the pilot not properly heating the thermopile due to pilot being too small or pilot being improperly adjusted so it is not heating the tip of the thermopile.


Hi Doc Rob,

I have a multi-meter, and I've tested the voltage from thermopile. With the heater off I get about 350mv. With the heater on I get about 400mv.

I think I've solved the problem, however. I'm about to post a follow-up.


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## wornways (Dec 10, 2009)

Hi again Ken,

Your suggestion seems to have paid off. As of about now (11pm PST), the pilot has not gone out in 72 hours. This seems like a miracle to me after everything I've been through with this heater.

There's more. The entire time I've lived here, the heater would take a very long time to warm the house, especially when it was below freezing outside. But since hooking up the old thermostat using wiring known to be good (power cord to an old laptop I no longer have), the heater has warmed the house quickly and kicked in and shut off predictably. For the first time since I've lived here, the heater maintains the house at temperatures within a 3F margin, whereas before (within that 8 to 14 hour period between outages) the margin was somewhere inside 12F. So this all by itself is a significant improvement.

Not once in the last three days has it been necessary to stomp the floor by the heater, thump the wall, rattle the thermostat, or any such behavior in order to get the heater to turn on. The heater now comes on right when the thermostat kicks in, and shuts right off right when the thermostat disengages. There has also been none of that on-off-on-off-on-off behavior I previously described.

Far as I can tell, thanks to your insight, we've found the problem. Somehow the wiring to the wall thermostat has gone bad in such a way (and I'm guessing here) as to periodically cause the current from the thermopile to run to ground, effectively breaking the current to the electromagnetic pilot valve for a moment--which was a moment too long. Perhaps this also caused an irregular flow of current over all, causing the heater to portray some of that ghostly behavior I described in my original post.

I feel less haunted now. I'm still a bit pessimistic and wonder if the heater will start going out again any time, but for the moment I'm at least feeling less haunted in general, a bit more relaxed in my own home.

I called the property managers today and told them about my amazing discovery, and we agreed to touch bases again on Wednesday if the pilot stayed lit without problem. If so, then they plan to rewire the thermostat with brand spanking new wiring. I also talked to the repairmen, and somehow their both a bit shocked and embarrassed and yet relieved and curious.

If anyone can offer an explanation of how less than perfect wiring between the thermostat and the gas valve could cause the heater and pilot to go out every 8 to 14 hours, please do tell. I'm very interested in knowing more.

I can't thank you enough, Ken. In fact, let me thank everyone who offered their insights. Without them I might well never have solved this colossal headache, still cold and temperature-mental. I'll report back in a few days with an update. Hopefully it will be good news.


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## wornways (Dec 10, 2009)

Hi Folks,

I'm still wondering if anyone can explain how "bad" or old thermostat wiring could cause the pilot to go out every 8 to 16 hours. When tested, the conductivity was measured at between 350 and 550mv, depending on the thermopile that was in there (we went through four of them don't forget). The repairman for the property managers came out on Thursday and rewired the thermostat to another room. There hasn't been any problems since, and the house keeps warm.

When he saw what I did with the thermostat sitting on the floor on the other side of the wall from the heater, and thought about what I told him on the phone about how there hasn't been any outages since I temporarily rewired the thermostat, he told me that he's talked with a few HVAC people he knows about my whole heater problem and this solution I came upon, and he said that none of them had ever heard of bad or old thermostat wiring causing the pilot to go out once or twice a day. In their experience, when thermostat wiring for a millivolt gas heater is bad in any way, the heater either won't turn on at all when the thermostat is engaged, or the pilot won't stay lit at all. In their experience there has never been any sort of intermittent behavior with regard to the pilot when thermostat wiring was bad or old.

So, if anyone could offer a reasonable explanation, I'd love to hear it. I'll also print this thread up and give a copy to the repairman.


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## log_doc_rob (Sep 5, 2009)

I have seen issues with a screw or nail that has punctured the 'stat wire and grounds it occasionally. I have also seen where the crimp connector has not been tightly crimped or it has been crimped partially on the wire insulation which would cause temporary main burner outages, but not pilot outages. 

There may be a spill or high temp. switch wired somewhere in line with the 'stat wire and you bypassed it when you rewired the 'stat. Make sure that you have a good carbon monoxide detector and good life insurance....just in case there is a safety sensor doing it's job causing the pilot outages.


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## wornways (Dec 10, 2009)

Hi Doc Rob,

I just went ahead and tried to remove the old thermostat wire to see what happened. It's definitely hanging on to something. I tried from both ends. At the wall end it comes out about 8 feet and then gets stuck. Feels like there's a knot in the wiring from that end. At the heater end, there is no give whatsoever, and there's a metallic *clink* sound about a foot high along the heater and some inches deep whenever I tug on it, which makes me think it's hooked up to something. Does that sound like a possible spill/temp switch?

Are carbon monoxide sensors sold that operate on battery and stick to the wall or ceiling much like a smoke detector? If so I think I'll swing by the hardware store today and grab one. If I can find one, where should I put it? Near the base of the heater? I'm new at this sort of stuff.

I'll also report your thoughts to the repairman and see what he says. It always struck me as a bit strange that he never pulled the heater out of the wall to double-check for any components that might be installed along the thermostat wiring. Based on your thoughts, I think I shouldn't write this off as solved just yet.


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## log_doc_rob (Sep 5, 2009)

The placement is detailed in the owner's manual. Most are recommended to be mounted at shoulder height, but that looks tacky. Some are battery operated and a lot plug in an outlet and have battery backup.


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## wornways (Dec 10, 2009)

There are no manuals for this thing, here in the house or at the property manager's office. And I haven't been able to find one online. Would you by chance know of an online repository of PDF manuals for Williams heaters?

I can deal with tacky if it means increased safety. I'll see if I can find a battery operated carbon monoxide detector today. There are very few plugs in this unit, all of which are far from the heater itself. Battery operated is the only way to go here.

We sleep on a futon that is close to the ground. Also, we sleep in a bedroom that is a foot lower than the rest of the unit. The heater is installed in a room next to the bedroom, right by the step down into our bedroom. Carbon monoxide settles, right? So it probably makes sense to install the sensor just inside the room not far from ground level. I have a place in mind that is inconspicuous.


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## JohnH1 (Jan 9, 2009)

Here is a link to the willams web site. http://e-wfc.com/ use the literature link at the bottom of the page and scrole to find your unit. The literature link at the top of the page is broken. FYI I heve never seen and willams product with no limit safety:no:. Eather it has been removed or you just havent found it. If it has been removed I would not operate it. I am assuming this is a wall furnace. Is it a direct vent or chimney vent style?


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## wornways (Dec 10, 2009)

Hi John,

It's a chimney vent. I'm looking through the PDF files now on the site you linked me to. I've been there before, but I didn't find my heater. So I'm looking now a second time.

Will you tell me how the limit safety works? I'm interested in knowing more about how I'm endangering myself at the moment.


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## wornways (Dec 10, 2009)

Hi again John,

I found the manual: http://www.wfc-fc.com/pdf/Monterey_Top_Vent_IOM.pdf

I didn't realize my heater was called a "Monterey" something. I just looked for "Wall Heater" something. No wonder. 

Page 10 shows that the thermostat is wired to a vent safety switch. Would you be willing to explain to me how that works?

Page 21 shows the vent safety switch and where it's located. It doesn't seem to be accessible without taking the heater out of the wall. Is this right? If so, then it's no wonder the repairmen couldn't find it. They only looked for a limiter switch some place in plain site.

Next question. Was the pilot going out because the switch was going bad or because the switch was doing its job? I suppose there's only one way to find out, and that would be to have the repairmen come out, replace the vent safety switch, and rewire it correctly. There's certainly enough thermostat wire left over. And I certainly don't want to endanger my wife and myself by bypassing the vent safety switch.


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## beenthere (Oct 11, 2008)

Limit switches are safety switches.
they only open because something is at the max safe temp/pressure/etc. And if they don't open and shut down what ever. An explosion or fire will occur.

Your switch either went bad because it was opening and closing doing its job. or because it was constantly just below its open temp. And finally got too weak to stay closed.


What caused the condition that weakened or worn out that switch should be checked for.
Operating your heater without it is a fire hazzard.


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## JohnH1 (Jan 9, 2009)

The draft switch is to shut the unit down in the event the chimney is not venting correctly. The way it is wired in the diagram will not shut the pilot off. I also do not see any limit in the instructions you linked to. The way they show the wiring is different from what I would expect. I would have expected to see the draft safety in the pilot curcuit to shut the pilot down and also a hi limit in the control curcuit. Anyway the way they show the draft switch will not kill the pilot. It should be servicable it senses the temp in the draft hood. A shorted thermostat wire to ground will cause the pilot outage. Hopfully you now have the problem solved.


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## beenthere (Oct 11, 2008)

The vent safety switch is a thermal switch.
So a gas that is over firing the burner can cause it to trip.
Or to weaken.


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## log_doc_rob (Sep 5, 2009)

Please correct me if I am wrong, but won't a hi-limit switch open if there is an obstruction in the exhaust impeding the flow of combustion gasses? If that happens, exhaust gasses and carbon monoxide can enter the home.


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## beenthere (Oct 11, 2008)

log_doc_rob said:


> Please correct me if I am wrong, but won't a hi-limit switch open if there is an obstruction in the exhaust impeding the flow of combustion gasses? If that happens, exhaust gasses and carbon monoxide can enter the home.


Not always. Sometimes the combusted gas will just cause flame roll out. And the limit won't get hot enough to trip.


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## wornways (Dec 10, 2009)

Everyone,

Thank you for sharing your experience and expertise with me. I've printed up the manual for my heater, and I've highlighted those areas necessary to convince the repairman that there's still more to be done, and that the assurance of safety is now the issue.

I'm also printing this entire thread, some parts of which I'll be highlighting for his reference. I believe that your collective assistance will lead to a proper solution to this longstanding heater headache.

I'm very glad I asked for an explanation of why bypassing the original thermostat wiring would cause my periodic pilot outages to go away. It rather sounds like a combination of some problem with the vent safety switch or the ventilation itself and a periodic grounding of the thermostat wire--perhaps through some kind of static electric buildup (ionization of dust or even dense or altered air particles to create an arc to ground). Bypassing the original thermostat hookup got rid of possible grounding problems to be sure, and it's stopped any vent safety switch related issues, but it's also left me with a heater that is categorically unsafe to operate.

I can plainly see now that for this matter to be properly resolved, the heater pilot needs to not not be going out while at the same time remaining hooked up to the vent safety switch--whatever this means. Initially, I'm guessing this is going to mean replacing the vent safety switch. But hopefully it will also involve a careful, professional analysis of this heater, its installation, its emissions, and its ventilation.

I'll be sure to report back after the next step has been taken.

My appreciation for your time and energy, individually and collectively, can't rightly be expressed. It's entirely possible that you'll have helped to keep my wife and I alive in this old house.


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## bobelectric (Mar 3, 2007)

Bad regulator.


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## wornways (Dec 10, 2009)

Actually, it turned out to be a pinched cord going from the heater to the thermostat. The heater itself was installed in such a way that as it settled over time, it slowly but surely pinched harder and harder onto to the cord. Eventually, it was through the cord enough for static buildup to arc to ground, causing the heater to shut off, including the pilot.

We bypassed the original cable, and everything worked fine from that point forward.

But this was months ago. I've since moved to another city and the old wall heater is now but a bad memory. I forgot all about coming back here and reporting the solution. Sorry about that.

It was impossible to test for because when you did a voltage check on the line, there was no problem. It only arced to ground intermittently.

Now that you've reminded me about this forum, I should post another mystery, with a central air conditioner unit, that has cropped up in my new rental.


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## ASanders (Jan 8, 2011)

I believe the answer to the question here is that the burner was flaming on and dropping right back out due to the bad t-stat wire causing turbulence in the burn compartment and basically blowing out the pilot. Seen it many times. I do find it hard to believe that there is no hi-limit or roll-out limit on this unit. If the valve stuck open it would burn the place down. The limit would drop out the pilot if it opened. But sound like everything is good now.


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## wornways (Dec 10, 2009)

It's a thing of the past now. I moved out of that place last August. Now I live in Reno with an HVAC unit that makes more noise than anything I've ever encountered before in my life. Particularly the air conditioner, which makes a never ending high pitched tick-rattle type noise that I can only briefly bring under control by just about hanging from the freon input pipe (from a condenser which is outside). Come spring, I might come here and try to get some help with this mad thing.


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## gasvalveguy (Jun 22, 2011)

*Williams pilot outage*

It sounds like the thermopile is overheating the cold junction cause nonsense shut downs. The pilot flame only should engulf top 1/3 of the Thermopile. And if the TP is to close to burner it can overheat it as well. 

By overheating the cold junction it will generate postive millivolts the once the cold jucntion overheats it will start to slow lose the millivolt signal till everything shut off.






wornways said:


> Hi folks,
> 
> I created this account for the sole purpose of seeking help with this problem, which I'm beginning to think is unsolvable or something to do with ghosts.
> 
> ...


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