Vent free system smells & sets off smoke detector - HELP!

Shane72 Posted By Shane72, Sep 16, 2008 at 2:12 AM

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  1. Shane72

    New Member 2.

    Sep 16, 2008
    Groveland, IL
    Hi there,

    We recently moved into a 5-year old home and I've attempted to turn on the gas fireplace 3 times now. In all cases, the fireplace has a smell to it (not gas, just an odor-- hard to explain) and then eventually sets off the smoke alartm in the room. It's a Monessen vent free if that helps at all. Everything is functional and great-- pilot light was lit, light switch on the wall fires it up. I've just never seen or used a vent free system and find it hard to believe that it's just supposed to "work". Can anyone calm my fears? Also, I thought at first that the fire was burning off the layer of dust that was in the fireplace (the house sat vacant for 9 months) but after the 3rd time and having the same result I didn't think it would be that.

    Any advice or recommendations?

    Thank you!

  2. R&D Guy

    R&D Guy
    New Member 2.

    Apr 25, 2007
    Shane could be that it was just burning off the dust. Does it smell like burning dust? Perhaps when no one is home you can burn the unit for 15 to 20 minutes straight and burn off any dust on the fireplace. Again, when no one is home and you can hang out outside with the windows all open.

    I've only dealt with the indoor radiant (non decorative) shop gas vent free units before that a buddy had in his shop and I thought it had a off smell too. I've never been a fan of vent free because of all the moisture which is created as a by-product of combustion, but most of all because of the silent killer aspect.

    Is your smoke detector a CO detector as well? Some just detect smoke, but I'd be sure to get one that detects CO as well since that's what the vent free produces.
  3. Redox

    Minister of Fire 2.

    Feb 23, 2008
    Burbs of B'more, MD, Hon!
    Those vent free things kinda scare me. They are not legal in a few jurisdictions and should come with a training video or something. Maybe go back to Monessan and see if you can get a manual?

    I would have expected all the dust to have burned off in the first few minutes of operation. The smoke detector might just be overly sensitive and need to be replaced. I think the recommended replacement interval is 5 years anyway, so for $20, replace it with a new one. Ionization detectors will go off on just about any product of combustion, even a relatively clean gas flame. Photoelectrric detectors are a lot more discriminating, so might be better for your home in this instance.

    I would also suggest a separate CO detector in the same room as the fireplace. Kidde (Nighthawk) makes detectors with a digital readout that can let you see just how much is in the air. The cheaper detectors just have a simple pass/fail algorithm that can be misleading. All are supposed to have a time weighting on their alarm so that a quick rise will set off the detector immediately, but a lower buildup will not alarm unless it lasts for a long time. Don't be surprised if you see a couple PPM after a few hours, but don't let it get over about 8 for very long. You may need to crack a few windows to keep things under control.

  4. webbie

    Seasoned Moderator 2.

    Nov 17, 2005
    Western Mass.
    Yeah, what he said.....clean completely. Check that the logs are set exactly per the manual.

    Do you have a CO detector?

    If the CO2 was too high, the logs would (should) shut themselves off - the ODS does that. The fact that it is a smoke detector going off points more to dust, etc.

    Have you painted the room, installed new carpet, etc.? These things can outgass and those chemicals are burned in the vent free.
    IN any case, get a hold of the manual for log placement, etc. and clean it well with a vacuum.
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