Older gas boiler not kicking on, but pilot is lit. Tstat maybe?


Old 03-04-12, 09:23 PM
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Older gas boiler not kicking on, but pilot is lit. Tstat maybe?

Hello there. Any help would be greatly appreciated with my boiler problem, it's a little chilly in here.

I have an American Standard gas boiler model # G 25 DPC. It's an older boiler, probably 40+ years old, and the house itself is a Victorian 2 flat over 90 years old. I have lived here for 2 years and this is the first problem I've had with the heat. The boiler heats 1 zone, the first floor, where I live. The pilot light is lit, but the burners won't fire. Not sure if the thermostat is functioning properly. Sliding the temp knob up and down the scale doesn't make the click sound as it should when it hits above the current temp. It seemed like it did maybe once out of many times, but no more, and no heat. Could this just be a faulty thermostat? It's also very old, probably original to the unit. Also, the circuit breaker the boiler runs on was tripped the night before last, but it was turned right back on and is fine. This lack of heat seemed like it might have coincided with the timing of it, not sure, might have just be a coincidence. So no, the heat hasn't been on for 2 days now - space heaters to the rescue! Also, the temp gauge on the boiler reads almost flat-lined at the bottom at 60, and for the pressure, large black dial is 14, and small red dial is 24.

Any suggestions of a first line of attack would be very helpful on this cool Chicago eve.
Thank You,
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Old 03-04-12, 09:36 PM
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Eliminate the stat, if it's heat only there is likely only 2 wires.
Jump them together and the boiler will light if the stat is bad.
If there is 3 or more wires, then the "normal" wiring convention is to use red and white wires to start a call for heat.
Failing that, we will need to look into the boiler manual and see what electronics are in there, might be a bad contactor
Old 03-04-12, 10:32 PM
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Thank you so much for replying! Ok, took the stat off. It is indeed only heat so there are 2 wires - the wires are pretty old, dirty, and gnarled, definitely original, I think this unit's from the 50's - but holding them together isn't doing anything. Bummer. I had faulty thermostat on the brain because just 2 days ago I replaced the stat in the 2nd floor apartment. The heat wouldn't shut off on their wall gas units (separate heating system from my boiler), but a new stat and bingo, fine now. So I thought what an odd coincidence that would be if the same thing was needed in my apartment. Guess not. I dug up the manual earlier today, am perusing it now. Some of it is making sense, some of it trying to decipher...
Old 03-04-12, 11:28 PM
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Are you renting?

It would be the landlords resposiblity.

I only ask because of your term " Apartment"

Sometimes the breaker needs to be switched off then on to reset them. Sometime they look reset when they are not.

Try that.

Next step would be verifying power to the boiler. Do you have a multimeter and know how to use it?

Mike NJ
Old 03-05-12, 12:54 AM
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Nope, not renting. This near 100 year old beast is mine, all mine. I say "apartment" because it's a 2 flat, with 1 "apartment" on each floor. I rent out the 2nd floor and live on the first. Your right, I guess that term is misleading.

Thank you for your reply. I did try switching the breaker on and off a couple times just to be sure. Actually I just discovered the problem. I started looking into the electrical, and I found that one of the wires coming in from the thermostat was a little loose and wasn't making contact. A-Ha! Maybe someone bumped it or something...? Tightened it up and put the Tstat back on, and now my radiators are just starting up again.

Thank you so much for the responses! What a great resource this site is, I'm sure I'll be surfing around for some more info. As a relatively new homeowner, I run into things I've never dealt with before, and I'm always trying to learn more about them. Hopefully there'll be something I can pass on that I've learned along the way. I'm pretty handy, but I couldn't call myself an expert in any field. I like trying to do things myself, rather than call someone in for the big bucks which aren't in my budget right now. My last tenant stopped paying rent and by the time a lengthy eviction went through, ended up owing me several thousand dollars, making the mortgage payments rough and draining my "house fund", so DIY is the preferred option. Anyway, sorry to ramble, and thank you again. You guys rock!

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