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Boiler not coming on, makes buzzing noise

mattm Member Posts: 40
Hi all,
I've greatly appreciated this board over the years, as I've slowly silenced and improved the performance of our one pipe steam system.

I've got a Weil-McLain PEG-40 boiler on a one-pipe steam system. The boiler is only a couple years old. At the moment though, it does not seem to be turning on, at all, and is making an electronic sounding buzzing noise. I turned the power off, and then on again, and heard what I thought was a relay click, but nothing happened except for the buzzing. Any thoughts on the problem, and how to reset?

I should add the thermostat set-up is a little different. This is a three unit building, with units 2 and 3 utilizing steam. So to prevent it from getting too cold in any given unit, there are two thermostats wired in parallel in each unit. My thermostat doesn't seem to be doing anything.



  • mattmia2
    mattmia2 Member Posts: 8,404
    does the buzzing go away if you turn the thermostats down or disconnect them? that may just be an isolation relay(or vent damper). Why the boiler isn't firing would be a different issue if that is the case. Does it have a vent damper?
  • mattm
    mattm Member Posts: 40
    Unfortunately, I only have access to my own thermostat at the moment. The owner of the other one is away. There is a vent damper, so that is probably the relay I’m hearing. 
  • mattmia2
    mattmia2 Member Posts: 8,404
    The vent damper doesn't have a relay, but it does have a motor and the damper has to open and close an end switch of some sort before anything else will happen.
  • ethicalpaul
    ethicalpaul Member Posts: 4,810
    Can you listen closely and determine where on the boiler the buzzing is coming from? Listen especially close to the gas valve to see if that's it. The damper should be far away from there, so it should be clear if it's one or the other.

    It might also be the transformer I guess
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
    EBEBRATT-Ed Member Posts: 13,795
    Could be the pilot ignition sparking. Take the cover off the boiler and post a few pictures of the gas valve and burners. You should see the vent damper shaft rotate from closed to open when the thermostat calls
  • Zipper13
    Zipper13 Member Posts: 229
    I had no heat and buzzing shortly after moving in a few years ago. After awhile I smelled what I can only describe as burning electronics. it was the damper on teh exhaust. short term fix was to force it to rotate open and it had a switch to lock it open so it stopped trying to rotate open/closed while I waited for the replacement to arrive.
    New owner of a 1920s home with steam heat north of Boston.
    Just trying to learn what I can do myself and what I just shouldn't touch
  • mattm
    mattm Member Posts: 40
    edited May 2021
    I took another look and it does not look like the buzzing is associated with the damper or gas valve. I circled the source which looks like the thermostat transformer. One added piece of Information, we recently switched from a preasuretrol to a vaporstat, which now that I think of it is when the problem started. I am not seeing any change in the damper shaft  

  • Jamie Hall
    Jamie Hall Member Posts: 21,536
    If you wired the vapourstat in exactly as the pressuretrol had been, that's not it. Besides checking the gas valve and so on as mentioned above, check all the wiring for continuity and good solid connections -- and then set about finding out where you have 24 volts and where you don't but should.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattm
    mattm Member Posts: 40
    Thanks, I did not wire the vaporstat myself and there are two black leads. Since it has been working some of the time, I assume that it is probably wired correctly. I’m getting a multimeter today and am going to check the vaporstat as per the Honeywell manual. 

    What should I be looking for with the burners? 
  • mattmia2
    mattmia2 Member Posts: 8,404
    Look at the schematic. All the safety and operating controls in series should have 0 v across them and there should be 24vac at the burner control then the gas valve. Should have 24vac at the transformer.
  • Derheatmeister
    Derheatmeister Member Posts: 1,472
    I see that you have a "Fan in the Can" to bring in the combustion air..
    How is this wired into the equation....Generally the call for heat activates it first then a proving switch allows the burner to fire ...Could there be a relay in this equation ?
  • alexft
    alexft Member Posts: 1
    Wondering if this was ever resolved? I have the same problem. 
    JUGHNE Member Posts: 10,791
    You should start your own posting.
    A quick check would be the isolation relay that might be under the front door.
    If you have one unplug and replug it. Sometimes it is a simple thing.