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finding exhaust gas leaks in pellet stoves

May 7, 2013
finding exhaust gas leaks in pellet stoves
  • This was a post to a specific question, and I realize I was very strong on the warnings, but better safe than sorry.
    I feel that the procedure outlined may have some merit & I didn't want to see the info buried on page 237, so I copied & pasted it here. You guys should go through it, and edit to your hearts content. Brush it up & polish it off,
    delete what you dont like and add on what you do like.

    It is a raw work, but 2 hours of typing ,none the less, so fix it up good. Thank you!>>

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    Im no expert, but from other posts I read here, sounds like you may have a small leak where the exhaust fan blower housing fits to the back of the heat exchanger or the gasket on the mounting plate of the exhaust fan blower motor, especially if either of these are in close proximity to the intake of the room air circulator or the center of the room air circulator squirrel cage rotor blades.

    I mention that because you say you only smell it when the room air circulator comes on, so baring an unlikely hole in the heat exchanger, you have some place near the room air motor
    intake , an exhaust leak that may be small and hard to see.

    The exhaust fan blower housing can get up to 500 deg. F , so use the better grade of RTV 900 *F
    or 1200* F black silicone seal for pellet stoves (milpak).

    Caulk with silicone seal any likley joints that you suspect might be leaking & you will probably
    calk the leak by accident , as it were.
    You will have to remove the sheet metal on the back of the stove and make sure the stove is cool & unplugged , for your safety,while you are in there calking.

    The silicone seal is easily removed at a later date if required.

    This , above ,is the FOOL PROOF METHOD. That does not mean it will work, it only means it is safe enough for a fool to do.

    ................................................................................................................................

    Another method which may work, I have never tried it, but it sounds logical, is to turn the stove on, without any Pellets, or remove the fire cup so that burning cant happen. This should
    create an air flow & you should have positive air pressure on the blow side of the combustion
    fan motor and a partial vacuum , negative or below atmospheric pressure, on the suction side of the blower. Make sure you close and latch the stove door so that the air flow is the same as when the stove is burning.

    BE VERY CAREFULL AND AWARE OF THE POSITIONS OF ANY WIRES AND MOTOR TERMINALS SUPPLING POWER TO THE AUGER MOTOR ,ROOM AIR CIRCULATOR MOTOR AND CONBUSTION FAN MOTORS, AS THESE MOTORS WILL BE RUNNING AND THE WIRES HOT WITH ELECTRICITY, 120 VOLTS AC.

    Buy a bottle of kids soap bubbles and a large cotton swab and wet areas suspected of leaking with the bubble solution. If you have a leak on the blow side , bubbles will form & if you have a leak on the suction side, the bubble solution may be seen to get sucked into the crack of the seam.

    The soap bubble solution IS A CONDUCTOR OF ELECTRICITY AND MUST NOT WET OR TOUCH ANY ELECTRICAL CONNECTIONS. BEWARE!! No mistakes allowed.

    Use a paper towell to blot up any errant run away soap solution, so as to prevent it from reaching any electric terminal.

    YOU NEED TO KNOW HOW TO RECONIZE AN ELECTRIC TERMINAL WHEN YOU SEE ONE.
    Most tax accountants cant recognize one.

    A safer way to preform this test, is to wet the suspect seams with soap bubble solution with the stove unplugged and then plug in and start the stove, without a fire.

    Its rough enough being in there with a strong light, looking for bubbles or soap being sucked into a seam and watching out not to get near a electric wire without worring about getting burned by hot sheet metal too, so disable the fire as described.

    Alternately, you can use dishwashing liquid & water, maybe not as easy to see as soap bubbles, and a kids squirt gun instead of a swab or as well as a swab, in case you want to reapply liquid to confirm a suspicion.

    There is some small danger involved with this test, so you cant get by blundering into it without any forethought, you need to be sober, alert, use good mature judgment, not be high or otherwise mentally impaired and think about what you want to do before you try to do it. You are in the position to know what you are capable of, not me.

    If you think you cant handle it, pay a professional or call factory service. Dont risk hurting yourself.

    A trick many repair men use in that situation is to unplug the stove before you start and put extra black electrical tape on all exposed terminals, so that in case you accidentally brush up against one, you dont get a shock. You dont need a lot of tape, just one layer stuck to each side of the uninsulated terminal for temporary insulation, as you will have to remove all the tape you put on after the test is done.

    The tape may catch fire or melt if you leave it on because it is not heat proof, so it must be removed. The tape is also evidence of unauthorized repairs and will void your absentee landlords warrantee , if you dont remove it.

    This is free advise and I take no responsibility for anything that may occur. Working around live electric wires is not for gomer pile, the village idiot or dumb & dumber or brain dead drunkard. It requires common sense & mature adult judgment, so if you think you may resemble any of those remarks, forget about running the motors and doing a soap bubble test and just unplug the stove and caulk everything.

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    Another method is to use a flashlight to find the leaks. Turn the lights off or at night, start/light the stove and inspect each joint. Smoke generally travels upward so place the flashlight behind or below the joint where you can more easily see any small puffs of smoke. It is important to perform this during initial startup of your stove, and when the pipes are already cold, as that is the time stoves produce the most smoke and any gaps are the largest. Once the stove reaches operating temperature and the pipes expand to seal any small leaks you have lost your opportunity to find most leaks, so simply shutdown, wait for everything to cool and start over.