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Long Run of vent

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by dexterj, Feb 8, 2008.

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  1. dexterj

    dexterj New Member

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    Salutations

    Have a 3yr old Whitfield Advantage insert that has been acting up this year, hoping some one can confirm some thoughts I have.

    We bought it new from a dealer who insisted on installing a very long run of 3in pipe up an exsisting and very sound concrete/clay chimney, 35 feet from top to bottom with about 8 feet running down into the basement with a clean out cap. Stove is on the 1st floor with a t-fitting. My guess at the time was that the dealer was more interested in thier bottom line than my stove - $1,200 for the stove - over $2,200 for the 35 feet of stainless 3 inch installed... What can I say - we just didn't know.

    Anyway, we have been tripping the vacuum switch this year having, foolishly, not made time this summer to run a brush up the flue. I've cleaned vent quickly a couple of times when the stove tripped off - it works for several days - then trips again.

    So today I went at it hard and managed to drop what appear to be several clinkers from the top of the vent near the cap. They aren't shinny, so I don't think I'm creasoding up - they are just hard packed ash chucks about an inch square from the top of the vent.

    So - and please feel free to elabourate on any of the above as well - what I am wondering is what would be the problem if I knocked the 15 or so feet off the top of the vent and let it exhaust directly into the old chimmey? It's in fine shape and was working great for the oil furnace and heater we removed when the stove went in.

    I didn't know about this forum and would like to thank the folks hosting it for their hard work - it's a really useful read just on it's own and I think I have a really good tip to pass along regarding silencing and extending the life of auger motor later.

    Cheers and best wishes

    Jon.

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  2. pete324rocket

    pete324rocket Feeling the Heat

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    Just so I'm clear and whomever else responds, am I to understand that the new pipe runs the full length of the chimney,that the stove is on the main floor(not the basement) and the cleanout is in the basement at the end of the run. Confusing to me is about the 15 feet you want to take off at the top of the vent??? and exhaust into the old chimney-I thought this pipe is already in the old chimney.You didn't indicate if there was a lot of soot at the end of the run where the cleanout is. New pipe shouldn't be so plugged or plugged at all. I would think this setup should work ok since it is shown in many diagrams for pellet installs where new pipe is set inside an existing chimney.There should be no obstructions though. See what other advice you get;you've already bought the pipe,its yours,maybe thats how it will be.
  3. dexterj

    dexterj New Member

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    HEY a brother easterner! Hurray!

    Yes - the vent runs the whole length of the chimney from basement to cap - there is a peaked vent extending out the top of the chimney and the old chimney has been capped with a plate - which holds the vent pipe up I assume. The stove is on the first floor and the primary vent from the stove has been cut through to the old chimney where it meets the run of vent with a t-fitting.

    What I am wondering is, can I simply remove the run of vent pipe and exhaust directly into the original chimney (assuming I pull the old vent out) from the back of the stove? The chimney is very sound and has it's own ash pit in the basement and frankly, I have to say I think the pellet stove would probably breath a whole lot cleaner.

    There wasn't much soot at all in the bottom - but got a grocery bag full when I ran the sweep up the pipe first time, and today several hard cake bits from the top. Here's a shot of the install from when we were renovating - so you know - there is no plaster or lathe - the wall is concrete direct on firebrick.

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  4. pete324rocket

    pete324rocket Feeling the Heat

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    But if not for the tripping of the vacuum switch,would all things be ok ? I mean as far as draw...any problem getting past a lazy flame in the pellet stove.I would think that would be the main thing to look for. In my situation,I'm in the basement also hooking into the chimney but it is lined with stainless pipe that is 6 inch-to handle a wood stove.There is more than enough draft.You say the stove is three years old-depending on how much pellets you have burned,it should have been thouroughly cleaned a few times by now.All I've got for now....yes a fellow eastener-living in the snow belt and about to be hit again this Sunday.
  5. pete324rocket

    pete324rocket Feeling the Heat

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    But to answer your question,I would say yes you could...and why not?
  6. dexterj

    dexterj New Member

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    Normally, I have the thing apart in the fall and clean it and the chimney completely - it's a bit of a hassle with the Advantage model we have has a fly ash pit in behind the firebox - so you have to pull the blower motor and turn it on it's side to really clean out the ash pit. Which is what I thought was wrong in the first place actually.

    It was more of a bit of bug hunt this time as I discovered that the 'vacuum' switch isn't actually run on a vacuum - it triggers off from backpressure in the flue rather than holding open with draw.

    Thus, given the very long length of vent in play, even the smallest backpressure seems to trigger the safety, which in turn stops the pellets, which increases the airflow into vent, which increases the pressure on the switch until it shuts down for lack of fuel. I'm guessing that with the high winds and rain we've had here in Halifax this year - it ran some water into the vent pipe and then caked up the ash that was was left in the cap as we hadn't cleaned it out as per usual. I noticed some water on the bottom cap the second time I swept the vent in fact.

    Frankly, I've never be able to get it to burn brown ash free as we tend to run it on #2 setting most of the time (24 hours for a bag of Eastern Embers) - it burns a little more grey on setting #3 (of 5). I've messed extensively with the blower and auger rates and simply can't get it to hold a fire that burns grey ash at #2 given, I think, the long run of fairly thin tube it must pressurize to pass the exhaust through.

    It's burning nicely at the moment and I have put a 1/4 hole in the clean out cap at the bottom of the vent tube/chimney to allow for momentary backpressure. It should keep it lit up for the season and I'm not too worried about carbon-M as the basement is un-used and the chimney still has it's doors and seals in place.

    It's currently drawing air into the small hole I put in, but I will be checking because I also know I am defeating the safety by opening that pipe at the clean out. (You know, in case someone else stumbles upon this thread some day).
  7. Corie

    Corie Minister of Fire

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    There is no reason a full liner shouldn't work. Really and truly, you're probably better off leaving the liner alone than dumping the pellet exhaust into a much larger cross-sectional chimney. Sounds to me like you just need some extra combustion air. IMHO though, that many feet of liner should have never been 3 inch. I would have required 4 inch liner because of the long pipe run. You're making the exhaust blower in the stove fight against a lot of frictional resistance in a pipe that long, imo. However the increased cooling and decreased gas velocity in the unlined chimney will probably do as much harm as good.
  8. dexterj

    dexterj New Member

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    Hey Corie - nice to meet you.

    OK - here is where my knowledge base sort of comes to an end and why I was so happy to find this board.

    We are talking about a 14 inch chimney straight chinmey from basement to stack top (no bends, no caps) originally lined for coal in 1921 - if I were 12 again I could probably have crawled up it to the roof. I thought, and I may be completely off base, but I thought that with this sort of chimney it would be pretty much like venting straight out through a wall.

    This assumes however that natural draw doesn't come into play so much with a pellet stove.

    And yes, in retrospect, I should have done as much research on the install as I did on the stove itself .. What can I say, we have still be able to heat our home very comfortably for a bag a day for the last 3 years. And up here on the frozen North Atlantic - that's pretty good despite this problem.
  9. pete324rocket

    pete324rocket Feeling the Heat

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    A 14 inch chimney is a pretty big hole and in my books is basically outdoors. I would wonder about the insurance company-you never know and if they say no way...well,it kinda makes it an easy decision unless you are into risks like that. Eastern Embers makes a good pellet-lots of heat-spruce so the bag says.I've often wondered what alder would be like as a pellet...or cherry wood. If you ever burned it in a regular stove,you have to watch you don't melt the thing! Wow it gets some hot!
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