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  1. #1
    Join Date
    Oct 2008
    Posts
    5

    Gas Fireplace Expansion Noise?

    Hi All,

    I have a Napolean BDG34NT installed in my basement. I hadn't ran it much up until now, but I did run it a few times to test it out. Now that I have finished the enclosure and the drywall I get some pretty bad noises after the fireplace goes off - they sound like duct expansion noises. Is this common in a fireplace? Does anyone have any ideas about how I might reduce or eliminate the noise? It is funny that it didnt happen before I finished the enclosure so I could have addressed it then
    Any help is appreciated, even comments on how frequent this occurs...
    Thanks!

  2. #2
    Join Date
    May 2005
    Location
    Madison, WI
    Posts
    1,078
    How many times does it do it, and how loud is it? I mean... would it wake you up in the next room over?

  3. #3
    Join Date
    Oct 2008
    Posts
    5
    Hey, it is fairly loud. Everything is open concept, but yea, it would certainly annoy me in the next room. It isnt any louder than some of the ****ty duct work that builders seem to do these days - sounds like a pop corn maker when my furnace runs! I'm just a little disappointed with this fireplace if it is going to be like that...

  4. #4
    Join Date
    May 2005
    Location
    Madison, WI
    Posts
    1,078
    It does it just once or continuously?

  5. #5
    Join Date
    Mar 2009
    Location
    Michigan
    Posts
    33
    It happens more than you know. Usually it will do it as it heats up and cools down. There are a few thing you can do.

    Majestic had a problem like this once. They sent a kit that included a coulple of 3.5 inch screws in it and rtv sealant along with a diagram of placement. The idea was drill a hole through the firebox wall and thread the screw through that hole until it contacted the outer jacket. Then a couple of turns more to put pressure on the firebox wall so it can't expand and contract. This would be a last resort.

    First I would disable the fan and superheat the fireplace by letting it get to it's maximum temperature (about 10 hours constant) for an expended period of time. The idea here is that it will take that much heat to get it to make the banging noise again and you will never get to that range under normal operation again.

    The last thing I would recommend is. If there is an optional brick liner kit for this unit put it in it could solve the problem.

  6. #6
    Join Date
    Jan 2006
    Location
    Powell River, BC, Canada
    Posts
    762
    This is common for many fireplaces. Some do it more than others. Most install/owners manuals will mention this as normal. When you 'tested it out' before enclosing it, how long did you run it for? You may not have had it up to the temps that you have now and therefore wasn't expanding/contracting as much. Another thought is how is the unit attached to the framing? There could be uneven pressure being put on it causing an increase in noise.
    Where are you? Are you done yet? I got ONE more call for you.....

  7. #7
    Join Date
    Jun 2008
    Posts
    110
    Quote Originally Posted by gasguy View Post
    Another thought is how is the unit attached to the framing? There could be uneven pressure being put on it causing an increase in noise.
    Usually this is the problem I run into they frame the unit in so tight that it has no where to expand and contract. Often theres a couple of noises but this makes it much worse. On retro's I tell the homeowner usually to leave a very very slight gap around the unit and this seems to work just fine. But on new housing they dont care they just want to sell the house and the guy who does the framing and drywalling wont be back, so we have this problem when the homeowner moves in. If you drywall extremely tight to the unit ive even seen it crack the drywall seams or crack the grout between ceramic tiles.

  8. #8
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    6,052

    Cool differential Dx

    Heat & Glo used to package a kit for expansion noise. It was 3/4" square tubing cut to specific lengths. You grabbed one bar, reached into the space btw inner and outer walls and rotated your hand until the bar cammed itself into place placing stress on both the inner and out walls. I submitted an idea similar to the one firebug describes and got them to sign off on it. It requires 5" screws on the sidewalls and 3.5" screws at the rear but it usually worked.

    We found one source after a really bad case: After the above methods failed, we replaced the unit twice but still banging. I was called in on the third unit. Once we pulled the second unit, I checked the floor for level. It was out enough causing racking of the unit. We leveled the floor so the box sat with no stress on it then secured the nailing tabs and never heard another peep. I did a followup at 6&12 months and quiet as a church mouse.

    If you try one remedial measure but it still bangs, you need to make a differential diagnosis before killing yourself throwing cures at it. Is it that box or the installation? Was the original unit properly installed? Is it operating to specs? I've seen bangers where the manifold pressure was too high causing the unit to overfire. I've seen where homeowners rearranged the log pattern to suit themselves causing hot spots on the sidewalls. Use a systematic approach.

    HTH,
    Hearthman

  9. #9
    Join Date
    Sep 2008
    Location
    Ottawa, Ontario
    Posts
    8
    If you read your owners manual you will see it is normal they call it tin canning.

  10. #10
    Join Date
    Dec 2006
    Location
    Portland, OR
    Posts
    18

    Exp. noise in an Infinity

    I've just run into a bad expansion noise in a multiunit condo tower. We sold Infinities for all the units (~50), and the builder used their own sub to install them. We got a call for the 1-year walk-through on one unit. We sent two different techs out, neither of them heard the noise while they were on-site, but each verified operation of the unit, and tried standard fixes like spacers, etc. All this from a fiber firebox lining, of course.

    H/O kept complaining, and I went out ~1 month ago. Per the H/O, the noise starts about 1 hour after lighting the unit, then periodically every 10 min. or so indefinitely. I had the H/O start the unit ~45 min before I arrived, and recorded the sound. I would post the MP3, but the apparently forum doesn't accept sound files. I sent the file off to H&G, and the Infinity product specialist started a case file, but their only suggestion, after what the previous techs had done, was to verify that the valve tray was sealed from the firebox, and report back.

    I'm going back out tomorrow for that, but that's a good point about checking the unit for racking or twist. I'll check that while I'm there. Incidentally, if anyone's curious, I have the MP3 I can send, just can't post it to the forum, and I'll report back if I find anything interesting tomorrow.

    I love this forum. I'm glad I found it.

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