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firebox modification OK?

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by schlemmer, Oct 6, 2006.

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  1. schlemmer

    schlemmer New Member

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    Hi. I've been trying to sell my wife on a wood stove insert for our fireplace. It's been a hard sell. The primary hang-up is aesthetics; she simply doesn't like the look of most offerings. Then I googled upon the flush-mounted Declaration/Elite 33/Perfect Fit. I saw one at a local shop today that was being sold as a floor model ($2800 w/all facing, etc.) I was pretty excited because I thought this was a very nice looking stove and got on well with our 1910 Arts & Crafts fireplace, and the faceplate extensions would cover our opening perfectly.

    So I get to looking over the installation instructions (gotten on-line) and make some measurements and it turns out that my firebox is a bit asymmetrical. On the left side the insert will just make it, in terms of depth, but on the right it will be proud by about and inch due to the sloping back of the firebox (and asymmetry). After some inspection and introspection I decided that it wouldn't be such a travesty if I could manage to dislodge a few of the offending bricks in order to squeeze this thing in.

    However, I then read in the "Do's and Do Not Do's" section of the manual that you should not alter the fireplace or chimney in any way in order to accommodate installation. So I guess my question would be is it a bad idea to remove a few fire bricks (which are surely backed up by lots more bricks in this rather substantial chimney) in order to make this work? Structurally, the firebrick can't matter but I'm not sure on the issue of heat. In terms of preserving the fabric of the house, I don't see it as an irredeemable act - the bricks could easily be replaced at some time in the future. It's not like blowing apart the smoke shelf.

    Thanks,

    Jim

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  2. webbie

    webbie Seasoned Moderator Staff Member

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    This is a bad idea for a number of reasons. In situations like this, I would rather see you remount the panels an inch further back on the insert (possible in many cases) so that the insert protruded an extra inch out of the fireplace.

    Or, simply place a sheet metal "return" angle on the face plates so the that face plate now looks wider, but is an inch out from the fireplace face.

    You might also carefully measure the floor model instead of using the manufacturers spec sheet...sometimes the actual measurements differ and it just might fit close enough.
  3. Rhone

    Rhone Minister of Fire

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    I had that problem. I got a mason to modify and see if it was okay to remove the bricks (the older your mason, the more likely they've built/repaired fireplaces like yours). He noticed the bricks in my situation did nothing for the structure and removed them, but concerned about how the firebricks lined up with cinder blocks seams behind, and about some cracks in the mortar of them. He ended up covering the back wall with some type of parging that held up to fireplaces & heat very well, and then covered the area with mineral wool insulation. He didn't like there was a framing wall on the other side of the cinder blocks with the the mortar being cracked like that, even though he did cover it with parging.

    So, I'd get a mason try to get an old one. Mine cost me $80 to modify my fireplace and he also removed my hearth tiles so I could put another in. Winter time is their slow time, and they love work indoors in winter. Though, winter hasn't really come just yet.
  4. schlemmer

    schlemmer New Member

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    Thanks for the input, guys. I think I'm close enough that I can go ahead and buy the unit, see how close it comes to fitting and then putz around from there.

    BTW, assuming I buy this unit, can anybody give me a feel for what I should be prepared for in terms of getting it into the house. Will the dealertypically deliver and carry it in for a fee? Should I try to round up a few friends? I'm doing all the liner work and aside from the fit issue, I don't see anything terribly complicated about the installation of the unit itself.

    Thanks again.

    -jim
  5. begreen

    begreen Mooderator Staff Member

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    If the stove shop will deliver and help get it in place, great, go for it.

    If you have to do it yourself, have a very stout hand truck or dolly on hand to roll it into place. The stove is very heavy. Prepare in advance. Have at least one other person to help you. I'd have four people if lifting is involved - one on each corner. Remove as much weight from the stove as possible. Make sure the path to the stove is clear and it will clear doors easily. Have some hearth protection in place. I have a 4' x 3' sheet of 22 ga metal that I keep for this sort of thing. As to the final install, sometimes you can get lengths of 1/2" galvanized or iron pipes under the stove to act as rollers. Or with the metal plate, the stove should slide in with some vigorous pushing.

    Finally, take your time and be safe. Your back and stove will thank you.
  6. elkimmeg

    elkimmeg Guest

    before an insert is installed in any fire box my question to you is how safe is the original fire box?

    Two critical areas to look for potential problems one the brick facing and the angle iron area position yourself witha flash light and inside of the fireplacelook up to the front of your angle iron areaz is there an open space between rows of bricks or the angle iron? Look all around that upper fire box and look for cracks viods loose motar or deteriorating fire bricks that entire are should be sealed tight to the damper. Now tap the actual fire bricks do you hear a hollow sound? sides and back top to bottom? If you do those fire bricks are susposed to be backed by solid masonry you just discovered you have a non compliant firebox . Believe me this is common. I will follow up a post for remidies my lunch hour is ending Oh if you have an ash dump door some rtv caulk would be a good idea sealing it tight . While at look up into your chimney liner system
  7. schlemmer

    schlemmer New Member

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    BeGreen -- Thanks for the tips. I'm approaching that age when my back is sending me messages after heavy or extended lifting. I gather I can get the unit plopped in my pickup truck. Getting it out could be the fun part. I've moved around a number of pretty heavy cast iron woodworking machines but none was this heavy and they could usually be broken down. Not sure what more I can do once I get the fire brick out of the stove. I do have a hand truck -- I'll check the rating on it. It just occurred to me that I might actually be able to back my truck up to our front steps. Wouldn't that be nice?

    Elk -- The firebox looks to be in pretty good repair, looks to have seen very light use in its 96 years. There are a few hairline cracks here and there but the angle iron lintel and surrounding brick are all in good shape. Everything I've been able to see of the clay flue is in good repair. Also, the mantel of the fireplace shows virtually no discoloration -- something I take as a sign of light use.

    But how hot is the firebox going to get? I mean, you've got wires and bearings back there -- can't get too toasty without regular failures of these components.

    The damper swings out of the way nicely and there's screws holding in pieces of 1/8" steel plates that I can remove to give me more than the 6" I need to get the liner through without ovalizing it.

    Which brings me to another point. I had been reading around hearth.com and elsewhere about the need or not to insulate the liner. I spoke to an installer today at a Travis dealership who said they almost never insulate the liner in cases like mine anymore. He said they put a wrapping of fiberglass insulation between the liner and the flue up at the top to keep the liner centered during installation and prevent heat loss through the chimney, but that was it. Does this sound like a good plan?

    Thanks,

    -jim
  8. elkimmeg

    elkimmeg Guest

    Fiberglass batt insulation has no business being used in a chimney. It is designed to be used in walls for insulation. Ask the person doing the stuffing, if they can provide documentation from the fiberglass manufacturer, to suport using that product for that application.

    I would be very interested in ther answer as this is another question I posed 11 years ago and no fiberglass manufacture writes specs for that purpose. If the manufacturer who makes the product, will not certify it for chimney application ,then who has the documentation or authority to use it there? Just because Biliiy joe budwizer, says he has done it for years, does not make mis using the product a correct application
  9. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    Agreed Elk. The pink stuff melts at a thousand degrees. That is why I bit the bullet and bought that nasty to work with, hard to find and costs like rip rockwool to stuff mine.

    Now when the chimney blows up, the house burns down and the stove melts there will be this unscathed column of rockwool standing up there.
  10. webbie

    webbie Seasoned Moderator Staff Member

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    As elk mentioned, many...if not most fireboxes are not built correctly. However, in my opinion, the installation of an insert and a liner does away with a LOT of the concerns about this, since the rear wall of the firebox cannot get to anywhere near the temperatures that it would with an open fire. My guess would be that with an open fire, the temp - and more importantly the radiant heat penetrating the masonry behind the fireplace could get up to 1200+ degrees - which would easily ignite wood touching it (or even close to touching) . Installation of a double wall insert - even it it touches the brick in a few places would reduce this greatly. Just guessing here, but I doubt that the far side of it would even get over 250, and most of the time would be less than 50 degrees over ambient.

    So, in my opinion, the installation of an insert in a non-compliant firebox...which 99% of them are...is a massive safety upgrade as long as chimney is lined completely with ss.

    I am against the idea of chipping out more than 1/2" or something tiny like that. Getting an old mason only means that he is probably working off old wives tales and will not be around when you go to sue him after the house burns. The old mason may also do crazy things like this, whilst perhaps the younger one knows better.
  11. elkimmeg

    elkimmeg Guest

    Craig the use of fire bricks is an allowance, reducing the required solid masonry supporting the fire box
    That's right fire brick fire boxes are not required they are used instead of 12" solid masonry.With the fire brick using the 2,5" exposure the supporting masonery requirement is reduced to 8". Removing them means you are 4" short of the required compliance.
    I agree with youe assesment of an insert being safer in the fire box than the fire box without one,

    That said, I should have directed the post to how safe is your existing fire box It is common to find that void between the front facing and the lintel. In many cases the space/void, is a clear shot to the combustiable framing header
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