inserting woodstove insert into zero clearance firebox

Old 11-10-02, 08:40 PM
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inserting woodstove insert into zero clearance firebox

I have a zero clearance fireplace that is totally inefficient and I want to install a woodstove insert. I found a few models that are rated for this type of fireplace but the main problem is height to flu. If I lower the deck (masonry floor) of the firebox by 2 inches (there would still be 4" of air space), and then fill in that 2 inch space with non-combustable material, would that be o.k. to do? I am even wondering about just taking out the metal fire box completely and relining interior? Anyone ever done any modifying of a fireplace like this?

Thanks for any information and/or suggestions.
Old 11-18-02, 05:31 AM
Join Date: Aug 2000
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Wood stove insert in zero clearance fireplace

Subject: Wood stove insert for zero clearance fireplace

I have a zero clearance fireplace. I would like to put a woodstove
insert in it. problem is my firebox in the fireplace angles off towards
the back, therefore the insert doesn't go all the way in. Is it ok to
have the insert sticking out about 5 inches. I could cover this gap with
formed sheet metal.

Only certain stoves are listed to place in a prefab fireplace. Make certain your manual says that your stove is one of these. If not, DO NOT INSTALL IT.

If it is OK, then the five inches is fine. You usually do not want to close off around these (except at the damper), so air flow can continue around the unit.

Please note: You can find extended informational articles at:
A listing of Products represented on HearthNet can be found at:
Retrieved 18 November 2002.

Subject: Federal Airtight insert in zero clearance fireplace

The original owner of my house installed a Federal Airtight wood stove insert into a zero clearance fireplace. I did not realize until a couple of years after I bought the house what a disaster this was. When having the chimney swept which meant moving out the insert I discovered that a 90 degree piece of galvanized duct pipe was used to connect the stove to the outer pipe of the chimney pipe and that only the outer shell of the zero clearance fireplace was still in place. Since the winters in central Texas aren't severe I have gone several years without using it or getting it repaired.

I have been told that the area where the zero clearance fireplace was will have to be bricked to make it fire safe for the stove to be used plus new chimney pipe installed since the pipe was damaged being used and a section fell apart when I was having it cleaned. I have searched your site and see that the older Federal Airtight products are not of the best design. The desire to use the stove would be one of creating atmosphere and to supplement the central heat during the times when Texas gets really cold or in the event of a power outage. It would not be used on any regular basis.

Should I spend the money on all the necessary repairs to use this stove or would the money be better spent on a new zero clearance fireplace if one can be reinstalled?

That's a difficult question to answer for me because I don't oversee your checkbook.

Here's what is boils down------older & even many newer factory built z/c fireplaces are typically not safety listed for use with a wood or gas stove, unless it's specific gas logs or an insert that the manufacturer also makes themselves.

Essentially, what you have is a Ford Escort that you've modified to go 4-wheeling-----not really designed for that application. And, the z/c's fireplace's flue system was designed for fireplaces, not stoves. Shoving a pipe up into the flue for a few feet is not the best way to do this.

Here's a question that only you can answer----do you want to have a fireplace in your home, or would you rather have a quality wood stove with large glass doors to see the fire which can heat the house, or be used as a secondary source? When you decide what that answer will be, only then can you move forward.

So, what would I do? Given today's stoves, I'd bite the budget bullet, take the darn fireplace out entirely, install a new high temperature Class A Solid Fuel Chimney System, sell the old stove and buy a new stove. Cost? Probably a few grand but then I'd have a safe system that will give me the things I desire for a long time. Here's a link to site for a solid pack chimney system I referred to earlier to give you an idea of what I mean:

Chimney info:
Retrieved 18 November 2002.

Make sure you purchase the correct insert for your application and that it is installed according to instructions.

Typical Fireplace Installation

In the "olden days" (yes, I was there), folks just shoved the stove in front of the fireplace, and stuck a piece of stovepipe up toward the damper area. If they were real smart, they fit some old fiberglass insulation around it so as to stop too much room air from escaping up the chimney (made the stove draft stronger too).
Chimney professionals soon saw that there were a lot of problems with this setup. The stoves drafted poorly, created lots of creosote and the more-than-occasional chimney fires ! As a result of these problems, the Hearth Industry and other agencies put together a set of more modern guidelines.
First, determine if you have a masonry fireplace and chimney. If you have a metal (zero clearance) fireplace and metal chimney, your options are very limited. Only a few inserts are tested for use in these "pre-fab" fireplaces. Check with your local Hearth Retailer --and confirm in the installation manual or manufacturers literature.

Assuming you have a "real" brick fireplace.......

Here are the basics

At the minimum, extend a 5 foot flexible stainless steel tube from your stove or insert up through the damper and into the first flue tile.
If the chimney is unlined, or if you want to do the best possible job, line the entire height of the chimney with stainless steel pipe (see your Hearth Retailer).
Seal the area below the fireplace damper with a metal pan , seal it tightly with furnace cement or high temp silicone
Always have a cap (spark arresting, if possible) on the chimney top.
Using another existing chimney
Houses with unused chimneys tend to be older homes, as these structures were often built with multiple chimneys for heating, cooking, etc. Often, these older chimneys are not safe to use without some upgrading. They can be lined with approved stainless steel pipe or restored with special masonry processes (ask your chimney sweep). Pay special attention to the wall pass-through, which is the area where your stove pipe will connect to your chimney. Any wood or combustible material in this area must be cut back to comply with building codes. Special insulated sleeves are available to accomplish this transition.

Install Wood Stove. Retrieved 18 November 2002.


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