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Our 83 year old house has a brick chimney covered up with drywall. We have no idea where the original flue was, but it must have vented a wood stove because there is no structure for a fireplace.

We want to install a zero-clearance wood-burning fireplace. The best place (to our mind) would be in the living room, which means that it would squeeze into a corner of the living room, with a doorway on either side of the hearth. I know we will have to install an insulated chimney liner esp. since there is combustible material against the chimney. Our rough plan is to place a lightweight floor protector, rather than a stone hearth, so the floor can bear the weight. Because we cannot stick the stove "into" the wall because there is no fireplace opening, the new fireplace vent would have to bend into the chimney at some point, and we would have to cut a hole into the brick chimney for the flu. Also, the fireplace will "stick out" into the room, so we will have to make a mantel/hearth around it that will basically eat up 1/6th of the living room.

I'm a novice at this, and am sure I've missed some details. Any advice or suggestions?

Is it possible to cut through the brick?

Is bending the vent pipe a good idea?

Will the chimney be a fire hazard even with insulated liner?

Our other option is to wait, and build a new chimney/fireplace into a one-room extension we plan to add to our two-story house. But everything I've read says never to do that... and that chimneys on exterior walls cause poor air flow.

  • Adding a builtin masonry fireplace would be large, complex and expensive project. I would recommend installing a free standing fireplace, like a Malm or Bainbridge fireplace. – Tyler Durden Aug 7 '14 at 16:04
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    Fay can you add a picture of what was behind the drywall? – James Aug 7 '14 at 17:52
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    90 degree bends in venting pipe is common and not a problem. I have a wood stove in my workshop that has 3 90 degree bends. – bowlturner Aug 7 '14 at 19:05
  • James, We haven't ripped out the drywall yet... I want to make sure I have my i's dotted and t's crossed before ripping out the drywall, in case it turns out it's not a good idea to add the stove after all... I do know, there is 2x4 vertical framing right up against the brick chimney, in one of the upstairs closets that is not completely drywalled, as well as a staircase butted up against it. That is why I was concerned about combustible materials. The chimney itself is single-layer brick. Tyler, I like the idea of a freestanding, zero-clearance fireplace - I think it would be easier on our fl – user24347 Aug 8 '14 at 13:57
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    Fay it is possible that there is in fact a fireplace behind the sheetrock. I lived in a house growing up that had been converted to three apartments and we merged them all back together. Not only did we find the fireplace behind sheetrock there was also set of stairs walled off in the back of the house. – James Aug 18 '14 at 18:19
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I realize this post is "old" however I wanted to post the answers as the information is always relevant to future question askers! :)

I sold venting pipe professionally for 4 years, and have experience designing a variety of systems.

Just a few notes: 1. Always check your clearances to combustible materials. Zero-clearance fireplaces are only zero clearance to certain materials, like masonry, etc. Make sure you take care when addressing this.

  1. Different stoves have different pipe diameters. If you're still debating which model to get, you could save yourself some money by going with 6" diameter versus 8", as the larger it is the more expensive.

  2. Old masonry chimneys are dangerous and should be inspected, even if using a liner.

Onto the parts! Since you are going to be dealing with a freestanding stove as well as a chimney liner, you're likely going to need an adapter as you enter the masonry.

When you come off of your stove with the flue pipe, you would want double-walled black stovepipe. This has a twist-lock connection that will go on your stoves outlet, either top or rear vented. It is more expensive than single-walled pipe, has less clearance requirement of 8 inches versus (18-inch clearance of single-wall) but has longer life, and isn't burning hot to the touch.

Your question about bending the pipe: Definitely do not ever physically bend a pipe to create a curve, etc. Rather, use an angled piece, then a straight, and then another angled piece to complete the connection. This stove-pipe comes with "elbows" at various angles. 45/90 degree are the most common, so you should have no issue angling the pipe to penetrate the masonry at 90 degrees.

The easiest way to complete your system would be to adapt the standard stove-pipe to a masonry liner. For a normal chimney-pipe to masonry-liner system, you will need a few pieces that aren't "standard" on most installations.

Masonry Thimble: This item installs into the 6-8" diameter hole you drill in your masonry chimney. It allows a length of straight pipe to pass through your masonry wall, into the chimney, and connect to the flexible stainless chimney liner. Stove-pipe to Liner Adapter: This piece physically adapts the rigid interior stove pipe to flexible liner.

You asked if the chimney can be a fire-hazard even with a liner; The short answer is yes. The reason being that if there is not enough clearance from the edge of the chimney interior to the outside edge of the chimney liner pipe; heat can be transferred to the brick, which can then catch wood aflame. If you have proper clearance, no fires should occur from the liner/masonry portion.

The only other fire-hazard that should exist is the chimney-cap itself. Make sure that the termination (last pieces) are done correctly. Is there a masonry chimney penetrating above the roofline a good bit? If so, you have it easy and can purchase a Turbo cap with a "spark arrestor" screen.. The cap spins as the heat exhausts out, cooling it, and the screen catches any flaming embers or sparks that might still exist from the burning wood.

Regarding your "Chimneys on exterior cause poor air flow" Statement: From my experience that is mostly false. Only in situations where there are EXTREME weather conditions does this ever occur. The reason this is never a problem with correct installations is that the Class A pipe required for exterior installations is either double wall or triple wall insulated. There are numerous layers of insulation that keep the flue gasses piping hot (ha) until they exit the chimney cap. Please keep in mind when designing a chimney system you want to achieve this: Most air flow. Least bends. Shortest run.

Numerous elbows/Angles cause the exhaust to cool. A rule of thumb is no more than 3 90 degree turns total from stove to cap.

I hope this helps!

  • Please include some photos to clarify, and maybe some links into a retailer's website where one might be able to buy each part. – wallyk Oct 2 '15 at 19:59
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Depending on where in the world this house was constructed 84 years ago, the chimney might be great, mediocre, or horrible. In the latter cases, I'd start by removing the chimney. This might allow re-framing to make one or two rooms a little bigger or provide closet space in addition to vent pipes.

Most modern wood burning fireplaces use steel vent pipe. You can greatly increase the comfort of firewood heating by installing another (smaller) vent to provide air into the fireplace to make up for the exhaust outflow.

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I have run into what might be the same situation. The chimney on our house looks to be about 30 years old. The previous owner had a wood stove sitting in front of the finished wall with the vent pipe running through the finished wall into the chimney. We did tear down the plaster in front of the chimney hoping there was a fireplace. What we found was only a chimney. The chimney was built right against the exterior tongue and groove wood sheathing boards. The boards were completely rotted to the point where they hardly existed anymore. The chimney looks like it has caused nothing but problems. I believe because the bricks collect moisture is the reason for the rotting wood. The joint where the roof shingles and chimney may not have been well kept either. The exterior siding was loose all the way up both sides of the chimney. From inside the house we could easily reach through the siding and stick our hands outside and touch the bricks of the chimney. It was letting squirrels, raccoons, bats, you name it into the house. A hole wasn't even noticeable from the outside. The siding acted as a door for the critters. Our solution is to tear the chimney down and get a ventless gas fireplace with mantle since we have natural gas. We like the idea of being able to run it for heat when the power is out and it will look better than a wood stove sticking into the living room 6 ft. I think you should open up the wall to see what's behind it. Hopefully you won't be as shocked and disappointed as we were, but if there are any issues you'll be able to take care of them before they get as out of hand as ours. Hopefully you'll discover a fireplace :-)

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    -1 because this is worded as a story rather than an answer to the OP's problem. Please focus on the problem and steps required to resolve the question being asked. – BMitch Dec 2 '14 at 5:22

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