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Thread: wood stove problems

  1. #1
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    Default wood stove problems

    I ve been burning wood as a house heating fuel for decades. I am not a beginner, I have other burners in various places and I have had everything from swedish log burners to AGAs and complete cooking ranges ...but.... I recently installed a cast iron free standing stove with a rear exit, so 120 mm horizontal out into a 90 degree and straight up in 120 mm stainless, out through the roof close to the peak and another metre and a simple hat to stop the rain, and it smokes like a b'stard. Cant open the door for a minute just to put another log in without the room ful of smoke. It is simply not drawing.The Man in the Shop suggested one of those globe shaped rotating vane gizmos on the top, but physics tells me, as it doesnt have a fan, it can only spin with the prevailing wind and how does that help? if it was driven by wind and if it had a small internal propeller I could see how it might draw up the chimney. but it doesn't. for the last few weeks it has been pretty much dead calm . whats going to make the rotating thingy rotate.....or if it spins because of the hot gases going up the chimney its being driven by the heat so how can it pull more?
    Any ideas
    Hurry up because either Im going to get lung cancer or end up looking like a side of bacon. it is keeping the rats out of the roof space though.
    'C'est la vie' say the old folks it goes to show you never can tell

  2. #2
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    Default Re: wood stove problems

    Can you replace the 90 with two 45s? Maybe its backing up pressure on the hard turn?

    Peace,
    Robert

  3. #3
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    Default Re: wood stove problems

    Does it smoke if you just crack the door part way for a few seconds before opening fully?
    Many airtights will require this step,to allow the accumulated smoke to clear, especially if there is a damper or secondary combustion that requires smoke to take a longer path to the exit.
    R
    Sleep with one eye open.

  4. #4
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    Default Re: wood stove problems

    Can you drop a small stone through the pipe from the roof?

    'Cause it sounds to me like there's some sort of obstruction.

    Dead possum?

    Also, how tall is this pipe?

    Tall enough that the gases could cool off enough to stop convection?

    I am puzzled.
    Rattling the teacups.

  5. #5
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    Default Re: wood stove problems

    "120 mm horizontal"

    5" flue pipe seems small for a stove of any size. More info required; outside combustion air, tight house, continous ventilation system? / Jim

  6. #6
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    Default Re: wood stove problems

    Is the stainless flue insulated?

  7. #7
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    Default Re: wood stove problems

    As I write this, I'm looking at my woodstove which is the same setup (rear exit to a 90 elbow). My chimney is about 7 meters & the pipe is a bit bigger than your 120mm - about 150 (6") - which may play a role.

    I actually considered a damper in mine, as the draft is really strong. Could you maybe have a kink or blockage in yours? When was the last time it was cleaned?

    ETA - my 90 has a cleanout in the bottom. Maybe ash/creosote has fallen down the flue & blocked things at the 90?
    "If it ain't broke, you're not trying." - Red Green

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    Default Re: wood stove problems

    90 bends can be a problem for draft. Stepping up the flue diameter right after the bend might help.

    Another thing to look at is the placement of the top outlet with respect to the peak of your roof. If it's downwind of the peak and below it, there might be an eddy current forcing the smoke back down. I think it's usually good to have the top of the flue above the peak of the roof.
    We're merely mammals. Let's misbehave! Cole Porter

  9. #9
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    Default Re: wood stove problems

    You'll get a better draft with two 45 degree elbows or even, as I did in a problem installation on a boat, three 30 degree elbows. This will get the smoke going nicely on a calm day

    You need something on top for windy days. A plain hole under a rain cap makes a messy turbulent exit. The whirlygig works by taming the turbulence inside allowing the wind across the top of the stove pipe to go straight across making a nice Bernoulli and thus sucking the exhaust gasses up.

    While common for proper exhaust flow with gas appliances, a whirlygig could be subject to soot gunking the axel and perhaps unbalancing the vanes. Which is why a pivoting vane cap that looks a bit like a conquistador's helmet that works by the wind making a partial vacuum on its lee side might be a better choice.

    G'luck

  10. #10
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    Default Re: wood stove problems

    I cured mine by adding another section of pipe on top. But opening the damper to full for a few seconds also helped. Smoke exit from the heater itself is around a deflection plate above the fire and then straight up

  11. #11
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    Default Re: wood stove problems

    Quote Originally Posted by Chip-skiff View Post
    90 bends can be a problem for draft. Stepping up the flue diameter right after the bend might help.

    Another thing to look at is the placement of the top outlet with respect to the peak of your roof. If it's downwind of the peak and below it, there might be an eddy current forcing the smoke back down. I think it's usually good to have the top of the flue above the peak of the roof.
    The top of the pipe should be 1 m. above the peak if within 4 m. of the peak. More if further down the slope of the roof.
    "If it ain't broke, you're not trying." - Red Green

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    Default Re: wood stove problems

    Thanks all...I changed two 45s for a ninety and its better. there's certainly no blockages . five inches should be fine for a shortish run, maybe 15 feet.
    now 20 degrees C in a sunny day , 0 or even minus a degree a two at night.. not humid at the moment.
    Bastard thing seems to be working better since I started this thread he he
    still whats with these spinning chimney topper jobs.
    does meteorlogical low or high pressure have an effect, just askin'
    'C'est la vie' say the old folks it goes to show you never can tell

  13. #13
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    Default Re: wood stove problems

    15 ft. horizontal run? There's a problem. Can you give it any slope up at all? even a foot in 15 would help. I bet you have to clean the horizontal part a lot.

    I think Ian got it when he said the spinning top will get gunked up (that's the technical term) really quickly. Atmospheric pressure will affect things - but not tons. A tightly sealed house will as well - there needs to be air coming in for it to go out.
    "If it ain't broke, you're not trying." - Red Green

  14. #14
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    Default Re: wood stove problems

    Very odd Jon, Had a bloke in Silves (he actually built stoves) ask me about a smoker. Turned out he had let some fiberglass insulation drop down the flue..

    The wizzy tops manage to spin with the wind and suck out of the flue, so quite useful. I had a client that was short of half her lungs, so smoke a real problem. BUT, she wanted to keep the open fire. So I fabricated a better throat for the fire and fitted a version of a Colt cowl (google it) over the Algarvien chimney pot. Worked a treat, esp as they were right on the top of the cliff in Albufeira and the wind was all over the place. 120mm sounds enough for what you are doing. Second Garret's getting well above the ridge. Odd thing is.. most probs dissapear once the flue is warm. Our gite has a rise of circa 5mtr of 125mm and draws like an illegitimate child..
    A2

  15. #15
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    Default Re: wood stove problems

    My damper (Gear Head Stove by Woodstock Soapstone Co) doesn't let much air in, even wide open. I open the ash pan clean out door for initial draft.
    Good luck

  16. #16
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    Default Re: wood stove problems

    Quote Originally Posted by David W Pratt View Post
    My damper (Gear Head Stove by Woodstock Soapstone Co) doesn't let much air in, even wide open. I open the ash pan clean out door for initial draft.
    Good luck
    The VT made stove that you can buy cheaper in NH.

    Nice stoves.
    "If it ain't broke, you're not trying." - Red Green

  17. #17
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    Default Re: wood stove problems

    Quote Originally Posted by Garret View Post
    15 ft. horizontal run? There's a problem. Can you give it any slope up at all? even a foot in 15 would help. I bet you have to clean the horizontal part a lot.

    I think Ian got it when he said the spinning top will get gunked up (that's the technical term) really quickly. Atmospheric pressure will affect things - but not tons. A tightly sealed house will as well - there needs to be air coming in for it to go out.
    backof the stove and up

    No No No 15ft run vertical straight out of the back of the stove not horizontal. no obvious reason why it shouldn't be drawing like a furnace.
    'C'est la vie' say the old folks it goes to show you never can tell

  18. #18
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    Default Re: wood stove problems

    Quote Originally Posted by Ron Williamson View Post
    Does it smoke if you just crack the door part way for a few seconds before opening fully?
    Many airtights will require this step,to allow the accumulated smoke to clear, especially if there is a damper or secondary combustion that requires smoke to take a longer path to the exit.
    R
    This.

  19. #19
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    Default Re: wood stove problems

    ok....more. there was a curved cast iron plate in front of the exit inside the stove so the smoke and heat had to curl toward the front of the stove , A Franklin baffle some one said... . I took it out and it is better, I tried taking out the grill base so the wood sits right on ashes on the base. Counter intuitive, but again a bit better, but then I changed the two. 45s and its a bit better as the draught control in the door is under the fire
    I have had stoves like this where you could open the door wide and it just roared. Has to be a chimney issue .
    Ian the pivoting vane cap thingy was recommended as even better than the spinning globe type by a salesman,, but still I cant see how either is going to work when there's no wind at all.
    'C'est la vie' say the old folks it goes to show you never can tell

  20. #20
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    Default Re: wood stove problems

    Greater inside/outside temp. difference is helpful, as is high barometric pressure.
    A hood or whirly on top will do nothing if it is calm,and will get clogged quickly if you get much creosote.
    Unnecessary and troublesome,IMHO.

    Does it ever draw? Like if you light up a bunch of kindling and paper?
    I get the feeling that there is a bypass draft lever somewhere.

    Taking out the the grate should be good as long as you don't overheat the bottom and crack/ warp it.
    A layer of sand is what we do,if there is no firebrick.

    The baffle should help you get more heat out of it and not stop it from drawing

    Is this a new stove?
    Any chance of a picture of your setup?
    R
    Sleep with one eye open.

  21. #21
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    Default Re: wood stove problems

    Well thanks everyone....Time to eat a huge slice of humble pie, and never assume anything, and back to basics blah blah.
    just been up on the roof to remove the simple cap and add another metre of 120 mm uninsulated stainless ....see where this is going ?....a big dork moment coming... and noticed a lot of dripped black tar on the flashing plate around where the chimney exits through the roof.
    I was up on the roof in the summer doing some tile repairs and certainly didn't notice it then. the hat was coated too. And as the whole installation was new about february and hasn't seen a whole season yet, I just assumed... .......so, peer down the chimney and there's an almost total blockage right level with the roof line big crusty black shiny crystalline grolly. Basically cleaned the whole four metres. and lets see....
    watch this space.
    'C'est la vie' say the old folks it goes to show you never can tell

  22. #22
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    Default Re: wood stove problems

    To help avoid just that issue code requires us to use insulated chimney pipe to go through the roof and for the outside section of pipe.

    Id put that baffle back in. The stove was designed to have it in place.

  23. #23
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    Default Re: wood stove problems

    Quote Originally Posted by StevenBauer View Post
    To help avoid just that issue code requires us to use insulated chimney pipe to go through the roof and for the outside section of pipe.

    I’d put that baffle back in. The stove was designed to have it in place.


    I’ll second that. “Smoke shelf” which helps with a secondary burn in the stove - makes it far more efficient. We had a Jotul Oslo that had that and a bar with a bunch of holes in it above the smoke shelf that drew in secondary air and pre-heated it. That hot air would hit any unburned material and it would look like you had gas jets up there. Clean burning.
    "The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails."
    -William A. Ward



  24. #24
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    Default Re: wood stove problems

    Spain seems to have very lax regulations for flues.
    We hired a holiday cottage in Cantabria, and the stove flue went up two metres, turned 90 degrees through the wall, and stopped.
    If the wind was anywhere from the east, the place filled with smoke- at one stage, we had flames coming out of the air inlets at the base of the stove.032.jpg
    Pic enclosed. You wouldn't want to open the bedroom window either!
    Last edited by birlinn; 01-13-2019 at 08:40 AM.

  25. #25
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    Default Re: wood stove problems

    Quote Originally Posted by StevenBauer View Post
    To help avoid just that issue code requires us to use insulated chimney pipe to go through the roof and for the outside section of pipe.
    I'm certainly no expert... but I would think that the flue MUST be insulated, in order to prevent the smoke from cooling off at the upper end. Cooled smoke is heavier, so it acts as a blocking effect... and creosote, etc., can condense there.
    "Reason and facts are sacrificed to opinion and myth. Demonstrable falsehoods are circulated and recycled as fact. Narrow minded opinion refuses to be subjected to thought and analysis. Too many now subject events to a prefabricated set of interpretations, usually provided by a biased media source. The myth is more comfortable than the often difficult search for truth."







  26. #26
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    Default Re: wood stove problems

    Quote Originally Posted by jonboy View Post
    Well thanks everyone....Time to eat a huge slice of humble pie, and never assume anything, and back to basics blah blah.
    just been up on the roof to remove the simple cap and add another metre of 120 mm uninsulated stainless ....see where this is going ?....a big dork moment coming... and noticed a lot of dripped black tar on the flashing plate around where the chimney exits through the roof.
    I was up on the roof in the summer doing some tile repairs and certainly didn't notice it then. the hat was coated too. And as the whole installation was new about february and hasn't seen a whole season yet, I just assumed... .......so, peer down the chimney and there's an almost total blockage right level with the roof line big crusty black shiny crystalline grolly. Basically cleaned the whole four metres. and lets see....
    watch this space.
    yikes, it was blocked with that much creosote?

  27. #27
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    Default Re: wood stove problems

    Well two hours later. been down the store for a set of drainrods. Lit it with a bunch of twiggy kindling before I went, came back to a toasty stove, all kindling gone, not a whiff of smoke. So up there now for a proper cleaning job and , yes, maybe put the franklin plate back in , sort the door seals. and so on.

    And the top section out through the roof will be a major operation to replace with twin wall pipe but I will rig up an insulated upper section some how maybe a 160mm dia pipe slid over the 120 , sitting on the tiles and the gap backfilled with vermiculite or some such. What fun. ! at least it ill be cosy tonight.
    'C'est la vie' say the old folks it goes to show you never can tell

  28. #28
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    Default Re: wood stove problems

    It was LeeG...to my surprise, and I dont burn a stick of pine. All cork oak, olive, some eucalyptus but not much, so good low tar hardwood... but sometimes a bit too green for my liking. maybe wet hardwood carries as much potential pyro lignaceous depoits as conifer.
    'C'est la vie' say the old folks it goes to show you never can tell

  29. #29
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    Default Re: wood stove problems

    Quote Originally Posted by jonboy View Post
    It was LeeG...to my surprise, and I dont burn a stick of pine. All cork oak, olive, some eucalyptus but not much, so good low tar hardwood... but sometimes a bit too green for my liking. maybe wet hardwood carries as much potential pyro lignaceous depoits as conifer.
    How long has your wood been drying?

  30. #30
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    Default Re: wood stove problems

    It varies from whom I buy it ...they all always swear its seasoned but I have two checks...strike a log and if it goes thock, its green, if it sings like a xylophone its at least a bit seasoned, and look for radial cracks on the ends of the logs, but I have just split some ash I felled two summers ago, logged into trunk pieces about 50cm diameter and 80cm long, out in all weathers, and we get 40C days on end in the summer...and i sawed it into maybe 20cm chunks as its easier to split and I was surprised how green it still was. But its burning well. Wood merchants are in my same favourite category as taxi drivers . Say no more.
    one guy delivered some tons once compete with weighbridge ticket, and it was wet-green and wet wet and covered in mud , and had little branchlets that even had green leaves on. He wants me to buy water and mud??!! I scavenge and gather, and saw and stack myself mostly but the busier and older I get Im more inclined to buy it delivered and stacked.
    I used the cord principle, but outside of the US and Canada no one seems to understand cords.
    four oclock in the afternoon and the fire's roaring away nicely. Can't believe I was such a prat on this one.
    'C'est la vie' say the old folks it goes to show you never can tell

  31. #31
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    Default Re: wood stove problems

    Good news on the simple fix.

    Hardwood will make plenty of creosote when it is wet or choked down.
    I looked through a house for sale that had creosote running down on the outer surfaces of the brick chimney in the kitchen.
    R
    Sleep with one eye open.

  32. #32
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    Default Re: wood stove problems

    Here, double wall pipe is used inside the building and triple wall ss pipe through the roof/wall and outside the building. For years in my youth (because poverty) I only used single wall pipe. Big difference, in performance and $$$ cost!
    The only heat we have is wood, and I learned long ago use a small stove burning hot, rather than a large stove burning warm. Still in spite of all about twice a year I have to clean an almost clogged "cap/screen" and sweep the pipe with a steel chimney brush. Always when it is storming outside

  33. #33
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    Default Re: wood stove problems

    Problems in store?
    My wood burner is the only heat source, and has a 175mm (7") twin wall insulated stainless flue. It's been going now for nearly 12 years, burns not-too-dry spruce, and the flue has yet to be swept.
    The flue is inside a 150 mm concrete block chimney, by the way.

  34. #34
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    Default Re: wood stove problems

    Depends on the stove.
    It sounds like yours isn't airtight.
    You should be alright.
    R
    Sleep with one eye open.

  35. #35
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    Default Re: wood stove problems

    Green/wet wood will definitely create creosote, as will closing down the stove before the fire really gets going. I realize that you have experience with wood, but I see people with many years experience throwing 4 logs on & shutting down the stove for the night. Within a few hours, there is creosote everywhere.

    If any wood still has green leaves on it, it's too green to burn. Even "seasoned" (now there's a definition that varies) isn't dry enough. Unless it's cut in the dead of winter, it needs a year split & stacked with ventilation. If cut well after the leaves have come off, you can get away with 6 months. A moisture meter should show less than 20%. Green will be 70ish. Eastern White Ash (Fraxinus americana) has a low moisture content & can be burned within a month of cutting & splitting.

    Even kiln-dried wood can be too wet. A friend got an expensive cord of kiln-dried & a bunch of pieces were 50%. The kiln operator must've filled the kiln too full and/or without enough air space.

    I don't know about where you are, but here in the states, Lowe's carries a tolerable moisture meter for $30.
    "If it ain't broke, you're not trying." - Red Green

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