# chimney question



## nnn4865 (Nov 16, 2011)

bear with me this may get a little long winded.  i live in denver colorado in a 1000s/f bungalow with a 1000 s/f mostly finished basement.  i want to put a wood stove in the basement primarily for supplementary heating.  winters are fairly mild here but we do get weeks of single digit temps now and again during which my boiler is running constantly and it still doesn't get warm enough. of course if running and maintaining the wood stove is not as time consuming as i think it might be i might use it more than i originally intend to.

  as the title says i have a question concerning the chimney.  i have an outdoor brick chimney with two clay lined flues.  one is 6 1/2x10 inch ID going to the main floor fireplace and the other is 6 1/2x6 1/2 ID which went to a fireplace in the basement which i bricked in and then furred out and drywalled over.  i originally thought i could line the flue to the basement and tie into that but the outlet on the stove is 8" so even if i could get a 6" liner down that flue it probably wouldn't be a good idea to reduce from the 8" outlet right?   i know that lining is always the best thing to do for both performance and safety but could i just tie into the existing 6 1/2x 6 1/2 without a liner even though the square inch cross section of 8" round is still bigger (but not by much) than the 6 1/2 x 6 1/2 clay flue ?   if these two options are not good i was thinking about putting the stove somewhere in the middle of the area and just running a pipe up to the roof.  the basement ceiling is at 7' and its about 15' from there to the roof penetration.  in that scenario would i have to use class a chimney pipe once it went through the basement ceiling into the main floor and then all the way through the roof?  and would the piping on the main floor have to be enclosed in a chase?  money being a concern, this method would cost well over $1500 just for materials. is there another more economical solution?

thanks in advance
john


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## Stump_Branch (Nov 16, 2011)

Sounds like you know what your looking at, can you take some pictures? Helps those with good knowledge see what you see.

Whats the stove?


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## nnn4865 (Nov 16, 2011)

the interior of flue is of the 6 1/2 x 6 1/2 that goes to the basement.  it looks like it was not used very much.  the basement fire place is centered between the widows behind the couch.  the wall was furred out and drywalled over.  house was built in 1928, has slab floor in basement and foundation wall is poured concrete about 12" thick. again the ceiling height is 7' down there.


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## SIERRADMAX (Nov 17, 2011)

That sounds like a large stove for an 8". And heating 1000 s.f.? Depending on the hieght of your chimney and the output of the stove you intend to install, you may be able to add a 6x8 reducer at the stove and run 6" pipe, tieing into a 6" thimble to the 6-1/2" flue.


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## nnn4865 (Nov 17, 2011)

in that set up are you saying straight into the clay flue without a stainless liner? that would certainly simplify the installation as well as cut down on cost.


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## begreen (Nov 17, 2011)

What is the stove make and model?


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## Backwoods Savage (Nov 17, 2011)

I'm always leery of reducing from 8" to 6". There is a reason the stove maker recommends an 8".


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## nnn4865 (Nov 18, 2011)

last winter i bought a scandia 315d off of craigslist for $100.  i believe this particular model is a copy of an older vermont castings defiant.  i'm embarrassed to say i didn't do the research before buying it.  just an impulse since it seemed so cheap.  i know most people will say to just scrap the thing but i did find comments from people that have used theirs for years with no problems.  the owner had just bought the house and the stove came with it so she could give me no information on it.  it had been used a bit judging by the soot build up in the stove and pipe going to the ceiling. unfortunately the chimney pieces in the attic were already gone, that might have been worth the $100.  anyway i had to totally dismantle the stove in order to remove it from the sellers house.  i cleaned all the pieces off with a wire brush and hosed them off.  the casting on all pieces seem to be pretty sound with no signs of cracks.    i replaced all the door gaskets and am planning on using the rutland sealant from a caulk tube when i reassemble it so that all joints should be sealed  tight. anyway i'd like to get the thing up and running and see if it works ok before just hauling it off to the scrap yard.  do you think it would be a good idea to fire it up outside after i put it back together just to check for leaks?  and again if it seems to work ok would reducing down from 8" to 6" be ok.  as i said before i only plan on using this stove to keep the house warm on the bitter cold days when my baseboard boiler has a hard time keeping up.
pictures are of stove dry assembled to keep pieces from getting damaged.


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## begreen (Nov 18, 2011)

Moved you over to the classic stove forum for this old fellow. The stove looks to be in decent condition. It is perhaps a bit coarser than the Defiant, but if you are observant and don't mind tweaking it a bit to assure good fitting doors, gaskets, bypass, etc., then it may be fine for you . Observe the bypass mechanism and assert that it works well. I'm not sure if Scandia also have a thermostatic damper on this model. If so, watch that for proper action as the stove is burning. 

The stove should be connected to 8" all the way. But you are only going to get a 6" thimble into that flue. I'd hook it up to the chimney with 8" pipe to a properly installed 6" thimble (emphasis on properly!) with a 6" reducer at the thimble and see how she runs burning good, dry wood. Pay attention to clearances with the stove pipe and thimble. There needs to be at least 18" away from any combustible (drywall, studs, ceiling, etc.)  

If you are getting good performance then fine. If you are getting smoke spillage and puffback, then consider selling the stove and getting one with a 6" flue. If you apply some stove black polish the stove should look really nice and you should make a tidy profit. I'd estimate it's worth at $250. If you do keep it, be sure to honor all clearances religiously. This stove should be able to put out a large amount of heat. Check to be sure that the clean out door on the chimney is sealed tightly. If it does draft fine, then I would next look at that chimney top. The flues appear to be at the same height. It wouldn't surprise me if you got smoke pulled down into the fireplace flue under the right conditions. There should be at least 6" difference in height. Also, I suspect that antenna is going to get sooted up.


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## nnn4865 (Nov 20, 2011)

thanks for the information begreen.  that oval outlet on the stove can be repositioned to come out horizontally on the back.  i thought it might be easier to just remove the furred out drywall between the windows and then open up the old fireplace and tie into the flue that way rather than have to go through at least 6" of concrete foundation wall to install a thimble.  of course i would probably have to remove the old block off plate and make a new one and place it higher up as the old one is probably at or below the level of the stove outlet on the back.  if i could do it that way, would i go 8" oval-to-round off the back of the stove and then 8" 90* elbow (or clean-out tee) and then reduce down to 6" to tie into a liner?  this method would also mean that there is only one 90* elbow in the path which i assume is also a plus. pics show the thermostatic controlled air inlet and the lever above the side door is for what you refer to as the bypass mechanism i assume. second pic shows the rear outlet option and the last pic shows the existing block off plate with damper on the main level fireplace which i assume will be present in the  basement fireplace.  as you can see the shape alone would make it problematic but it is also too low to utilize as is anyway.

on another note can someone tell me the correct product for reassembling the stove. i was looking at the rutland black stove and gasket cement.  it comes in a caulk tube and says it can bond metal to metal and withstand 2000* temps.  is this what i want to use?


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## mdocod (Nov 21, 2011)

Normally not a good idea to reduce down, however, in your case, the smaller pipe size may actually be a blessing. My understanding is that most stoves with 8" flu have the larger size in place to accommodate the exhaust of a very large burn possible in a very large fire box. If you keep your wood loading limited to smaller quantities, the ~6" flu should operate just fine. In your case, with a relatively low heating demand, you'll probably only be firing up the stove with smaller wood loads anyways, so the flu size should be alright, albeit, perhaps not up to code. For smaller fires burned in the unit, the smaller flu size is actually preferred as it will produce a stronger drafting effort for the small fires and be less apt to develop creosote build-up since the flu gases will have less surface area and less time to cool and condense. 

Begreen nailed it on the suggestion to alter the termination of the chimney to prevent smoke from down-drafting into the fireplace above. I was thinking the same thing.


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## remkel (Nov 22, 2011)

Whoa- that is a whole lot of stove for 1000 sq ft. You will certainly be warm.


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