Utica Boiler M-175-AGB Won't Run - Suspect Gas Control Valve?

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Old 03-27-14, 07:37 PM
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Utica Boiler M-175-AGB Won't Run - Suspect Gas Control Valve?

Several times this winter, I've awoken to a cold house. I first check the pilot sensing thermocouple as it seems to go bad generally once per season. However, for the time being, it appears to be okay. Looking for other potential causes of "no heat", I try turning off the power to the boiler briefly, turning the gas control from ON to PILOT and back to ON, turn the power back on, and wallah, the boiler comes to life! I'm stumped as to what the problem could be: low gas pressure, bad control valve, ??? This 'fix' has worked several times now and this problem is occurring now with more frequency and the lady of the house is not happy! Help and ideas appreciated to get me out of the dog house ...
 
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Old 03-28-14, 12:40 AM
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Sounds like a "soft" lockout. Soft lockouts are restored by merely turning off the power for a few seconds and then re-powering. Try this next time without monkeying with the gas valve and see if it comes back on.
 
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Old 03-28-14, 03:19 AM
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Thank you Furd. It's happened a half dozen times over the past few weeks. Should I investigate the 24V power supply (transformer)? I don't want to have to resort to power off-power on to get the system running. I'd like to get to the root cause and fix it once and for all.
 
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Old 03-28-14, 06:16 AM
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Have you changed the battery's in the t stat??? Try that first...
 
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Old 03-28-14, 06:22 AM
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I don't want to have to resort to power off-power on to get the system running
This wasn't suggested as a 'fix', but a 'diagnostic step' in order to determine where the problem lies.

Furd wants to know if cycling the power ALONE, without monkeying with anything else at all, will reset the system.
 
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Old 03-28-14, 02:58 PM
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Okay - I'm going to wait for the system to die again so I can test the power cycle only theory. Stand by ...
 
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Old 03-28-14, 03:10 PM
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Steve, how about the t'stat battery? You sure it's OK?

I can't seem to locate that model number on the Utica website... can you take a clear photo of the data plate please?

Never mind, I found it...

Ummm... on second thought, there are three revisions. Can you tell from the data plate what REVISION boiler you have?

MAGB boilers are COMMERCIAL units. Is this in a residence?
 

Last edited by lawrosa; 03-28-14 at 03:52 PM. Reason: Greyed out sentence bugged me. Changed "back to black"
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Old 03-28-14, 03:26 PM
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OK... I thought I found it... but I don't think so...

So, let's go back to a picture of the data plate please.
 
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Old 03-30-14, 08:48 AM
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All four AA batteries in the two Honeywell stats tested okay - however, one terminal (-) was corroded and blue. I cleaned that up and replaced all the batteries. This is likely my problem - thank you Hurd, lawrosa, and NJ Trooper!

Pictures attached ... tough to get a good picture!
 
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Old 03-30-14, 08:53 AM
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PS: Yes, this is for a residence.
 
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Old 03-30-14, 09:13 AM
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Can't be the "MAGB" that Utica has on their website, none are that small, they START at 500K BTUH!

I'm not sure what model that is...

But hopefully the thermostat was the problem, keep us posted and let us know.
 
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