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Tight clearances

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by begreen, Aug 29, 2006.

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  1. begreen

    begreen Mooderator Staff Member

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    We are ready to start on the flue for the new stove location. It is a 2 story installation, with a flat ceiling on the first floor. We'll be putting in a 6" flue. I'd like to have double wall in the living room, and class a from the 2nd floor through the roof (about 3 feet on 2nd floor).

    The best location for the class a support box is in the first joist cavity. The first, 2nd floor joist is 16" oc from the wall. The next joist cavity over has a recessed light in the way, but I don't mind removing it if I have to. But it would mean that I would need an offset in the living room and another in the class a to avoid the roof rafter where it penetrates the roof. Not so desirable. What to do?

    The 12" Duratech support box puts me right at 6 or 7 in from the wall with the double-wall pipe I think. Is this too close? Excel's system has a 10" support box which would help, but the stove shop I am working with uses DuraTech.

    Would this setup work with the 12" Duratech support box? Duratech says min clearance to combustibles with their DVL pipe is 6". Is that correct? Any thoughts?

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  2. brian_in_idaho

    brian_in_idaho New Member

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    Begreen, with double-wall I think 6" is the min distance to combuatables, so your 12" box sounds like it would work. But doesn't that also put your stove very close to the wall? I'm inferring a few things from your description. Do you have a truss roof, or rafters/joists? Sounds like stick built, you can cut out part of 1 joist and support a cross-member between the remaining 2 joists to pick up the cut end. I don't know if this would help, I wouldn't want to cut the roof rafter if it could be avioded. I'm sure you will hear from guys that know a lot more than me.

    Good luck.

    Bri
  3. buildafire

    buildafire New Member

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    Brian' right, BeGreen. What are your stove clearances? If the pipe collar sets in a couple inches from the back of the stove, you would have to have 4 inch clearance or less to the wall. I haven't seen a stove with those clearances since 1990... I usually start with the closest variable and work in. I'm not sure I would cut any of the joists without getting very good on-site advise. Very bad deal if you cut the wrong thing... If you have to elbow, moving the class A system toward the interior of the home could cost more in chimney pipe height, but it may save you a class A elbow set ($$$) and provide better support for the system in a storm.
  4. begreen

    begreen Mooderator Staff Member

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    Yes, DVL pipe is rated at 6" min. clearance, so we just might make it, though I'd prefer a little more room. We'll most likely go with a Jotul (Castine or Oslo) rear-exit from the stove into a cleanout tee. That should give us good clearances for the stove.

    The house is stick built, rafters and joists. We'd prefer to minimize the impact as much as possible. Setting the stack in the first, 2nd floor joist bay is good as long as clearances are not compromised.

    This will be an offset, corner install. With rear heatshield, the Jotul Castine has a corner clearance of 11" with straight-up double wall. The Oslo gets this down to 6", so I think we will be ok. But for the Castine,, they list the pipe to wall clearance as 7" even though DuraVent lists DVL pipe at 6". For the Oslo, they list it as 6". Confusing. I'm assuming that the Oslo doesn't run much cooler than the Castine. What to do when there are conflicting specs?

    -- added top down view

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  5. MountainStoveGuy

    MountainStoveGuy New Member

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    Is the 7" clearance on the castine making you maintain the over all stove clearane with the heatsheild? I will look into it.
  6. MountainStoveGuy

    MountainStoveGuy New Member

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    The stove itself has a 7 inch clearance. Thats why. The olso has a 6" overall clerance, letting you maintain the pipes clearance as well.
  7. begreen

    begreen Mooderator Staff Member

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    The diagram supplied with the manual shows the 11" measurement coming from the corner of the Castine, but maybe this translates to 7" from the pipe? If I come out ot the Castine from the rear, into a tee, then my corner clearances to the stove itself are increased to over Jotul spec. Then it seems the pipe-to-wall clearances should be governed by the listed pipe manufacturer. This is the case as soon as the pipe becomes class A. Is this correct or will the inspector just go by the stove manual?

    If I am correct. What is the best way to keep the maximum distance for the double-wall pipe from the wall, short of cutting joists? Is Excel's 10" support box the best way to go or should I look at other options? If I use the Excel support box, does that mean I need to use their pipe all the way?
  8. MountainStoveGuy

    MountainStoveGuy New Member

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    The stove manufacture trumps the pipe manufacture, so if you are reversing the flue, technically you need to maintain a 7 inch clearance per the castines manual.
    If you use a particular brans support box, then you have to use there pipe. They interlock.
    I would get the Oslo :)
  9. begreen

    begreen Mooderator Staff Member

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    The Oslo is where I started. Wife loves the Castine and feels that the Oslo just "looks" too big for the space. Would you install the Oslo if you were in a climate that is 20-30 deg. warmer in the winter than Boulder? It's snowed enough to stick only a few times in the past 10 years.

    I did some more measuring and poked a hole alongside the 2nd floor joist. Good news, I have 20" to the downstairs wall. So I am ok with DuraVent or Excel pipe. It looks like the Oslo could just fit as a direct connect. The Castine would work with rear exit into a tee.
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