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Soot block formed in outside venting

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by MaryVLKay, Feb 12, 2013.

  1. MaryVLKay

    MaryVLKay New Member

    Joined:
    Feb 12, 2013
    Messages:
    2
    Loc:
    Massachusetts
    I have a Harman Advance Pellet Stove that I've been using to heat my cape style home for 2 yrs. The only time I use my furnace/oil system is when I leave the house for more than a 3 day period. I clean it out every week. I use the Room Temp /auto mode set to 75 and the feed set to 3.5-4, depending on the temp outside. It's worked perfectly until 6 weeks ago, when I noticed a few issues going on: the temp in the house drops and it doesn't consistently go on automatically, the flame is much larger now-reaching up to the top elements there, the glass used to take the full week to get blackened around the edges-but now it gets that way within a couple hours. I had my son check this out and he thought it wasn't venting properly, so went outside and dismantled the pipes. He found that soot had almost entirely closed the vent pipe at the top of the elbow. Cleared this out and the stove has been a little better now. Still doesn't operate automatically and the glass still accumulates more grey film and black than it did before having this issue. My question is this: What caused the soot to collect in the venting pipes to begin with? The installation was done to Harman recommendation. My set up looks like this: I have a straight pipe coming out with one elbow (down low). This goes through the Harman part that goes through the house. One elbow and straight up above roofline outside. Worried that this issue will repeat itself if I don't find out what caused it. Thanks!

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  2. SmokeyTheBear

    SmokeyTheBear Minister of Fire

    Joined:
    Nov 10, 2008
    Messages:
    12,061
    Loc:
    Standish, ME
    When was the last time the entire flue was cleaned, combustion blower, any internal exhaust air passages, the esp, when was the last time you checked the stoves gaskets.
    save$ and Mr. Spock like this.
  3. Mr. Spock

    Mr. Spock Minister of Fire

    Joined:
    Jan 2, 2013
    Messages:
    514
    Loc:
    SW MA
    Agree with Smokey. Had a member here with a similar issue. Entire exhaust path inside the stove was plugged solid. If your venting was that bad the innards of that stove need attention.
  4. save$

    save$ Minister of Fire

    Joined:
    Sep 22, 2008
    Messages:
    1,916
    Loc:
    Chelsea Maine
    Clean first, then consider the leaf Blower Vac. thing. If you don't know about it, go to www.youtube.com and look for cleaning a pelletstove with a leaf blower. You will get into places you may not have been able to. cheap and fast. I use it after every ton burned. one of the best pointer I have ever picked up on to really get a stove working like new.
  5. MaryVLKay

    MaryVLKay New Member

    Joined:
    Feb 12, 2013
    Messages:
    2
    Loc:
    Massachusetts
    Yes, entire flue was cleaned out using a brush I use for my clothes dryer and vacuum. I use a soft paint brush on the combustion blower and vacuum in the weekly clean up. Have to learn exactly where these internal exhaust air passages are located....don't know what the esp is??? and don't exactly know how to check the stove gaskets. I called Harman and checked my door gasket with a piece of paper-trying to slip it through along the door-that was tight. But I know the glass was cleaner longer the first week we cleared the block, and now it's slowly returning to the same issue-two days after the cleaning this week, I already have black halfway up the glass. I'm thinking there is something wrong with the venting and wondering if I should add additional external air flow directly to the stove? A friend thought the cap on the top of the stack might be the culprit. I get a random vibration that goes away on it's own, and think whatever is causing that might expose a root issue here. But it burned fine through the entire last winter season. Can't figure this out.
  6. SmokeyTheBear

    SmokeyTheBear Minister of Fire

    Joined:
    Nov 10, 2008
    Messages:
    12,061
    Loc:
    Standish, ME
    When cleaning out the flue using that brush did you also go back towards the stove (the ESP is located in this path inside the stove do not go poking around until you have found the ESP and removed it for cleaning) or just up the flue?

    The cap at the top of a flue is also a good spot for ash to build up and they need regular cleaning just like the flue does.

    The ESP (Exhaust Sensor Probe) is a device that is held upright in the exhaust path after the combustion blower (looking from the combustion blower). Its function is to measure the exhaust gas temperature, using this measurement, the controller settings and the room temperature probe the computer on the controller makes adjustments in the air/fuel raito and firing rate of the stove. If this probe is dirty it will make a mess of the stove's burn.

    You should be able to locate the ESP by use of an exploded parts diagram in the installation manual.

    Now if you tell us a detailed parts list for your vent system we can figure out if your venting is contributing more than it should to your build up situation.

    There is a multi part series on youtube detailing the cleaning of a Harman Advance http://www.youtube.com/results?search_query=cleaning a harman advance&oq=cleaning a harman advance&gs_l=youtube.3...1455.8899.0.10162.25.22.0.3.3.0.178.2563.6j16.22.0...0.0...1ac.1.eMyeUU0ZaoA

    Pellet stoves require regular cleaning based upon ash produced, it is not something that can be scheduled without knowing how much ash is ending up where in the system.

    When a manual says once a season it is usually every two to three tons, if you burn high ash pellets it can gum up everything rather fast the best premium grade pellet produces one fifth the amount of ash than the worst premium pellet.
  7. Bioburner

    Bioburner Minister of Fire

    Joined:
    Aug 4, 2012
    Messages:
    2,976
    Loc:
    West central Mn
    The colder weather this year has made a few of the external exausts condense the flue gases sooner and more problems with bad draft. Check and clean the entire venting system and find the esp, the sensor for the brains of a Harman.

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