Replacing the thermostat with a new one did nothing to fix my problems with the bedroom heater. If anything, things got worse.
Yesterday I woke to bedroom temps in the low forties. After breakfast and walkie I took the new thermostat off the wall, checked the wire connections – fine – cleaned the male and female contacts between the two parts of the thermostat – almost certainly unnecessary – put it back together and that did me no good at all. Really flailing for an explanation, I pulled off the heater’s front grill and opened the sightglass cover.
That’s all I did. And at that moment, the burner lit – without the slightest drama or sign of any problem at all. And left like that, the heater kept running fine all day. Turned on and off just as it was supposed to.
I went to bed last night, first closing the cover on the sightglass. Woke up this morning to temps in the low forties. The heater hadn’t functioned at all, all night long. I hopped to the heater, flipped open the sightglass cover, and…
…the burner immediately lit. And it’s running fine as I type this.
This makes exactly zero sense to me. The only … possible hint?
When the cover is open it rests against the pilot thermocouple fitting. Now, what bearing that could have on the situation, I have no clue. The thermocouple controls the pilot, not the main flame. And anyway the cover appears to be resting against an insulator so that’s another way it couldn’t have any effect.
And yet – sweartogod it’s like throwing an on/off switch. I am utterly confused.
Well, you have made great progress in troubleshooting. Now you know that the Thermostat likely isn’t the problem. I assume that you have checked for loose connections at the heater end of your thermostat cable?
Combustion air intake maybe clogged? Opening door allows air to enter .
The old EE in me (graduated almost 43 years ago) says you have a) bad battery in the unit or b) loose contact screw or c) a broken wire between the thermostat unit and the heater either to the thermocouple itself or to the relay that triggers the main gas release.
The vibration or pressure makes it work, remove the “resting” weight and it quits. I would run a new wire which is cheap and use the old thermocouple.
If the symptom continues with new wires its a bad thermocouple, if it solves the issue, bad wires.
To test without running wires – remove the wall unit face plate. Short each circuit related pair of wires at the furnace with an alligator clip and ohm same two wires at the wall plate. Resistance should be zero or real close to that, if infinity – bad wire.
Ohm the thermocouple (cold), there should be a spec somewhere that says what the resistance should be.
Beyond that, no clue because the relay is obviously working as it lights when the sight glass is open which means the electrovalve is also working.
Good hunting
Odd – I can’t see any of the other 3 comments. Hope mine posted.
Grounding it?
If your comments work , when you put the metal cover on the thermocouple , it gets it grounded.
I’m confused too, because WP says there are 6 responses, but it isn’t showing me any.
So, perhaps my conjecture is a repeat. Is that mounting tab for the thermocouple also the ground for it? Maybe you have a bad ground there, somehow, and that cover for the sight glass is touching the tab when it’s open, and making the ground contact. Possible test would then be to use a little jumper wire from the tab to the chassis. This assumes, of course, that the chassis provides common ground, which it appears to do. Or, I’m completely wrong, but hey, it’s worth a shot.
For some reason I can’t see any comments to any post.
Eric.
Perhaps the pilot is starved of oxygen? Could you run tests, like holding the sight glass cover open but not touching the thermocouple to see if it still works that way, or leaving the sight glass closed but leaning something of equivalent weight against the thermocouple? If it is a case of lack of oxygen, I would suggest some rodent has built a nest blocking where the oxygen is supposed to come in.
Sounds to me like you have a broken TC… throwing the sight glass cover over might just be forcing a broke wire into contact… the 2 wires for something this size are not really a large gauge… you can pull the whole wire from the thermostat to the heater and replace it… as the TC is only a two wire assembly its fairly simple, just a PITA depending on how it is run… you heater manual should be able to tell you what kind of TC it is.. there are T-type, J type, K types, etc… From my days in test engineering the folks at Omega Engineering (Omega.com; 1-888-826-6342) are the go to people for this and you can order direct from them…
I am having serious WordPress problems here, guys. I can’t post at all, yesterday people couldn’t comment at all but having other people read them is apparently still not a thing. I’m just putting this comment here because it’s the only way I can currently put words on the blog. I don’t believe it’s on this end and I really hope all the changes indicate activity on somebody’s part.
Comments are broken?
BTW, I don’t know if it is just me, but I can’t see the comments on this one, not even the one I made.
Well, I am very confused as to why the comments have disappeared, but we still see the count increasing.
I cannot see the comments in this post. Why?
For some reason, comments are no longer showing for me – not just on this post, but other ones as well. This post shows 15 comments, but I can’t see any of them.
Replace the whole damn piece… Spendy but there’s failures, glitches…. and gremlins. Can you get an assembly?
.
I also can’t see the comments on my phone.
comments?
Your comments are not appearing….
comments not showing up if you didn’t know already
.???
Sounds like a limit switch was open.
I would check if its venting properly.
Probably a ground circuit.
Leave the cover open. Looks like there’s glass.
Why can I not see any comments?
JMW
Sounds like there is a ground fault somewhere. You’ve cleaned the wires/connections at the thermostat end, can you do the same at the heater end? It might actually be a fault in one of the wires. Can you test continuity? Do you or one of your neighbors have a multimeter or some other test probe? At the low voltages in control circuits it doesn’t take much movement of a wire to restore continuity.
Why are replies hidden?
c
Test
ing
Very odd… The posting tells me there’s 31 responses but none can bee seen from this end. Someone else likely already mentioned it but I cant tell. So FWIW the metal sight door is likely grounding out on the screw that holds the thermocouple completing the circuit necessary for ignition.
32 responses and I can’t see any of ’em. Weird. I’m not getting e-mailed updates anymore either. I’d ask if anyone else is having these problems, but I wouldn’t be able to see the replies…:-(
Did you know that no comments are showing in your posts the past few times? It say what the number of responses are but you cant see them?
I can’t see comments.
Okay, now the comments on all your posts are verfucked…
After 40 years in the business. Looking at the picture your thermocouple that generates the millivolt electricity to run things is the flat metallic looking wire. It will go to the red terminal block. Take a screwdriver and work all the screws on that block. The thermocouple only puts out 3/4 of a volt so any corrosion under the screws will affect the operation. Work them back and forth a half a turn a few times. Good luck
I don’t see any responses?
Cant see the comments
Is this why I can no longer see comments, here?
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i’m confused as to why I cannot see the 40 responses to Okay, now I am very confused
I cannot see the earlier comments so this may be a duplicate. If the cover is touching a metal ring on the furnace temperature sensor flange it may be making a ground connection that corrosion between the furnace temperature sensor flange and the furnace frame is preventing. You might take out the furnace temperature sensor to see if the probe is coated with carbon deposits. I had similar problems with my furnace and cleaning off the probe and flange let the furnace work for a month or so while I waited to receive a new probe. I think I had to buy a off brand furnace temperature sensor for my furnace.
What happened to the comments?
b
Hey Joel, checking in to see if everything is ok, and to let you know that comments are no longer showing. SLee
All the comments have disappeared. Is it something wrong on my end or is there evil afoot?]
Almost a week. Blog is broken : (
still broke?
I don’t know why I cannot see any of the solution-offering responses. I was interested in reading them. I’ll see if I can figure out what has changed.
needs more oxygen/ AIR
How come I can’t see the comments?
Brave, Chrome, another computer, using a vpn – no joy.
I can’t see comments on other posts either.
Did I offend someone?
hello, Joel,…
can’t see comments! hope all is well.
Testing
Uui
55 posts preceding.
Cannot see them…
Prayers, hopes, peace, and perseverance.
X
I can’t see any of the responses. Is it a problem at my end?
Just nod if you can hear me…
Pull the thermocouple and clean it with a brass wire brush. Sounds like it’s not quite heating up enough, and when you rest the cover on it it shifts up just enough to be more in the flame. You’d be surprised how often I end up on a call for something similar.
Welcome back . . . with thanks to Claire!
Kentucky