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Having a problem with a WEIL Mclain CGI ( GAS SMELL)

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Danscrew
Danscrew Member Posts: 130
in THE MAIN WALL
Just got a call from my brother in law. His Weil McLain CGI has a slight smell of gas when it shuts down ? controls are Model 1107-1 any ideas no faults all the lights are green when running

Comments

  • Fred
    Fred Member Posts: 8,542
    Is this a recent install? Sounds like maybe a leak in the gas supply line or at a connection around the gas valve.
  • Danscrew
    Danscrew Member Posts: 130
    no older install i had him check all the fittings with bubbles you only smell it right after it shuts off?
  • KC_Jones
    KC_Jones Member Posts: 5,915
    Slow closing gas valve perhaps?
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • Tim McElwain
    Tim McElwain Member Posts: 4,658
    Put a combustion analyzer on it when it shuts down and see what your readings are. Make sure you have a good draft and that there is no blockage in the flue. Bring all the fans in the house on and check draft. Do you have a fireplace which could cause a reverse flow on the chimney when it is running.

    Have him call the local gas company to come and check for any leaks or poor combustion issues.

    Is the smell coming out of the front or from the draft diverter?
  • Danscrew
    Danscrew Member Posts: 130
    Its a direct vent you get a little smell of gas when it shuts down like KC Jones said it sounds to me like a slow closing gas valve is that possible? I had him bubble check all the pipe joints in and around the gas valve and all seemed tight . The temps here in New York are 22 with a wind chill of 12 and dropping
  • Fred
    Fred Member Posts: 8,542
    Does the vent have a gaurd of any kind on it? Nothing crawled into it trying to stay warm did it?
  • Danscrew
    Danscrew Member Posts: 130
    Its cleared they checked it and there is a screen to protect from things crawling in thanks Fred
  • Fred
    Fred Member Posts: 8,542
    Are all the burner tubes clean and properly seated? Do they all fire?
  • Danscrew
    Danscrew Member Posts: 130
    I am going to give it a look tommorrow i was thinking on changing out the gas valve ?
  • Tim McElwain
    Tim McElwain Member Posts: 4,658
    What is the Make and Model of the gas valve? it is probably unlikely that it is the gas valve so it is at best just guessing. Usually when this occurs on older equipment an adjustment to primary air will solve the problem. That and as I suggested check inlet and outlet gas pressure and do a combustion analysis. Sometimes increasing gas pressure at the outlet without getting any increase in CO will give more inspiration to the burners and they will consume all the gas on shut down. You must however when increasing pressure by screwing down on the gas valve regulator do a complete combustion test to insure safe operation.
  • Danscrew
    Danscrew Member Posts: 130
    The valve is a Honeywell VR8204 A2001 when i got to his house he had the new valve so i installed it and got the same thing after it shuts down you get a whiff ? Tim thanks for all your help a little baffleled Dan
  • Danscrew
    Danscrew Member Posts: 130
    Spoke to Weil Mclain and they said the house is in a negative pressure . Its a direct vent with no outside air coming in to replace the air that is removed. thanks to all Dan
  • klarock
    klarock Member Posts: 1
    Can you tell me how this was resolved please? Having this same issue. 
  • Bridgestone
    Bridgestone Member Posts: 29

    I had a WM CGI4 boiler installed in early 2023. I've noticed a slight smell of gas only when the boiler shuts down, lasting 3-4 minutes. The gas company found a trace of gas near the gas valve but not enough to red tag it. WM provided a new gas valve for replacement, but it didn't help. Same smell. The same tech company came back to clean the burners, check the gas pressure and do a combustion analyses. All tests were normal and he said that he couldn't do anything about the gas smell. The system heats well, but the smell is annoying.

    Regarding the house in negative pressure, the new boiler replaced a 32 year-old WM boiler. Same footprint in the basement and same venting to the outside of the house. No gas smell. Also, when I force the new boiler to short-cycle, starting again in w/i 3 minutes by using just a small zone, the pre-purge sucks up the gas smell and sends it out the vent. The inducer motor on the new boiler has higher rpms than the one on the old boiler.

    It's been suggested that the smell could be combustion fumes and not gas. After doing more research on that possibility and having a retired chemist take a whiff at the boiler, I believe it's gas. He thought it to be a gas smell. It doesn't have a chemical or formaldehyde smell and carbon monoxide is odorless.

    I'm wondering if others are having, or have had, this problem. On another forum someone said that when the post-purge is complete a small amount of gas remains in the manifold/gas distributor and then escapes for 3-4 minutes. Is this considered normal? I'm thinking that the digital control panel may have the gas valve closing too slowly or the flame-out too soon. I'm not optimistic that anything involving the digital control panel can be serviced.

    Any thoughts are appreciated.

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