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NG gas fireplace too hot?

Post in 'It's a Gas!' started by jaiken, Oct 5, 2010.

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  1. jaiken

    jaiken New Member

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    I have a Superior GDV5000 natural gas fireplace insert, direct vent out the back, installed in 1989. It has always seemed to run very hot, but not enough to trip the overheat safety t'stat. The brass coated decorative trim on the top turned black from heating many years ago, but it didn't bother me enough to be concerned. Now the problem: The fireplace surround has been noncombustible brick. I have now had the brick covered with a wood surround and am concerned that the wood above the fireplace is getting too hot. The wood above the fireplace begins about 6 inches from the top of the fireplace. The fireplace has a circulating fan. The wood is getting too hot to touch. I cannot leave my hand on the wood at all. I do not have an infrared thermometer, but I am assuming that the temperature is above 160 F. My question is: Any guesses on why this fireplace is getting so hot, and might there be a way of adjusting it to burn a bit cooler. By the way, the air shutter is full open. Thanks for any comments you may have.

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  2. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    The air shutter has NOTHING to do with the heat, but if you have an NG model, your flames must look like crap.
    unless blue happens to be your favorite color...
    NG requires less than maximum air-to-fuel (ATF) mixture, & the shutter is generally shut down to achieve a yellow flame.
    Did you try turning the regulator (if it has one) down to decrease the flame size & the heat output?

    If you truly have a gas burning iappliance that is an 89 vintage model & it STILL works, consider yourself lucky.
    A unit that has worked this long is the exception to the rule & owes you nothing.
    The newer units are more efficient & more realistic looking & all in all are better than what you have.
    If you're REALLY worried about using it, it may be time to think new, IMHO
  3. jaiken

    jaiken New Member

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    Thank you for the quick response. The owner's manual does not show clearance to a mantel above the fireplace, but wood being too hot to touch can't be a good thing. I think that you are saying that the only way that I can get less heat output above the fireplace is to turn the flame down by lowering the gas pressure to the orifice. Is this correct? I'll hire somebody to do this if I have a regulator on that line. The fireplace does have a circulating fan. It is prop type and seems very ineffective, so I don't think that redirecting the air would help all that much. If all else fails, I'll go with the heatshield.
    I'm the original owner, so I know the fireplace got its longevity from lack of use. It has direct venting out the back, so I believe that replacing it will require removing exterior siding, taking out wall studs and replacing it from the rear. I have talked to a couple local gas fireplace dealers about my replacement options, and they don't seem to have a better idea than what I mentioned. So I'm looking at making the best of a bad situation until I bite the bullet and do the replacement. Yes, the flame looks like crap, and this model relies on a "ceramic and lime salt flame colorization rod" for its yellow color. It never has looked all that well compared to the newer ones. The owner's manual says that the air shutter should be full open for NG and open 1/4" for LP. Seems backwards to me, but I'm no expert. What do you think?
  4. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    Ah, the old "Golden Embers!" You've got an antique compared to today's units. You are correct in the removal procedure - unless you want to change the inside looks as well.

    One thing you CAN try is to find the shut off for that particular gas line & try closing it a tad to see if you can reduce the flames, but I'm starting to think that replacement (we call it a gas-to-gas tear out) may be your best option.
    Good luck!
  5. jaiken

    jaiken New Member

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    Thanks again Bob. You didn't comment on the air shutter setting. Does having it wide open sound right for this old DV fireplace? I did try closing it, and it did improve the looks of the flame. I didn't notice any sooting, but it looked like the flame could be lifting a bit so I put it back to wide open. Does this make any sense to you?
  6. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    The air shutter setting for ANY unit is just what I said before - ATF ratio.
    The laws of physics haven't changed, so - in MY experience - all the way open for NG is incorrect.
    Your manual may have a misprint.
    Lifting flame is generally a result of lack of combustion air at the burner, & I suppose the air
    shutter could cause this effect, but I've NEVER seen it happen...
    In order to get sooting, you'd almost have to close the shutter completely down.
    1/4" sounds right for NG not LP...
  7. pyrotom

    pyrotom New Member

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    Agree with all Bob's comments.

    If you use an infrared thermometer to check your wood mantel and it never reads more than 190 degrees F, you are probably within design specifications. Flash point for wood is generally considered about 500 degrees, but wood that has been heated for long periods of time and is dried out may ignite at much lower temperatures.

    I find it odd that the manual doesn't give you some sort of clearance to combustibles. I also find it odd that the manual seems to be giving you the opposite settings for the air shutter. Technically, if the flame is lifting, that's too much primary air, and you remedy it by closing the air shutter. Or throw some embers on it. :)
  8. jaiken

    jaiken New Member

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    I know this thread is getting off my original question, but I'm confused about the air shutter adjustment. Bob says that flame lifting is from lack of air (shutter too closed) and Tom says its too much air (shutter too open). I would appreciate your clarification. I am still looking for more comments on the question: What can cause a direct vent fireplace to run too hot? I don't think that burning the plating off the brass trim could be normal, so I'm asking for things that should be checked.
  9. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    I have to disagree here, Tom. Everytime I've encountered "lifting" or "ghosting" flames, it had NOTHING to do with the air shutter setting.
    It was either not enough combustion air (blocked intake) - or insufficient O2 (intake air mixed with exhaust gases)...
    The air shutter adjustment closed too far turns the flames bright orange with black (sooty!) tips...
    Too open - turns them bluer than blue, but I've never seen them lift with the shutter wide (NG)...
    A closed air shutter can cause the flames to burn higher as they seek O2, but the bottoms stay on the burner ports.
    I will admit to having only 10 years in the trade & not running into EVERY possible scenario,
    but I'll stick to my story
  10. pyrotom

    pyrotom New Member

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    As usual, I have to agree with Bob. He is exactly right, but we're talking about two different things.

    Lifting or "ghosting" is always due to insufficient secondary air, that is, air introduced above the burner to achieve complete combustion. This is pretty common on tall vertical terminations, when there isn't enough restriction on the exhaust.

    The other type of lifting, due to too much primary air (coming into the air shutter), will cause a blue flame to lose contact with the burner and is usually associated with a little tiny roaring noise. It may be more common with LP than NG, but both will do it. On propane, the older Heat & Glo SL36 & 6000 burners had delayed start problems because they'd soot up if the air shutter was closed too far, but the flame would lift when it was too far open. If you threw a couple mineral wool embers near the pilot assembly it might solve the problem. The same issue arose with the old DSI models, where you'd lose flame rectification when the flame lifted.

    To get back to Badger7's original question, real solid or plated brass is a poor choice around any fireplace, because the lacquered finish degrades and leaves you a nasty brown/black finish. If you can get the finish off, you should be able to polish it back, but brass is sort of passe these days, so I think you'd be better off just spraying them black with Stove Bright fireplace paint. if you look closely at most "brass" on fireplaces, you'll notice that it is gold anodized aluminum, which does better in the heat.

    Which brings us back to the original assumption, that the fireplace is "too hot". Have you taken its temperature yet?
  11. jaiken

    jaiken New Member

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    OK, thanks, I think that I will make sure that the intake and exhaust air passages are clean and then move the air shutter to optimize the flame color. I will make sure to stay away from shutter positions that so not cause soot or flame lifting. As far as being too hot, I will take the temperature of the wood above the fireplace and if its still above 160 F I think I'll try baffling the circulating air so it isn't such a direct shot to the wood. If that doesn't work I'll see if I can look into a heat shield that isn't to obnoxious. If all that fails, we leave it turned off till we can do a replacement. Thanks again for your help.
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