Chimney flue for wood and oil?

Question

I have a chimney which is utilized for a oil burning furnace. I know I can not add a woodburner to the same flue. If I wanted to install a woodburner, how big (diameter) does the flue have to be for each. And what kind of cost is it to install two flues into a pre-exsiting chimney? Or is it just worth installing a new metal chimney off the side of the house?

Answer 1

I have a wood and oil furnace and they use the same flue. It's metal lined with an insert.

Answer 2

You are correct in saying that you cannot use the same flue for two heating appliances. It may still be legal in a few areas but it's dangerous everywhere.

For a woodburner chimney, try to use the same size flue pipe as the outlet of the woodburner. It'll usually be either 6" or 8". As an example, my Woodstock Fireview soapstone woodstove has a 7" outlet. I used 6" pipe with the appropriate adapter and ran straight through the ceiling & attic to the exterior. Six inch stainless pipe is cheaper than eight inch.

It can be a real bugger to install a new metal chimney into an existing flue.

Double-walled stainless insulated chimney pipe is quite expensive but lasts practically forever and has excellent heat-insulating properties, making it ideal for most installations and very safe. I recommend it highly.

It is usually (but not always) cheaper to run the woodstove chimney straight through the ceiling. If you buy a stainless chimney kit, it should include an adapter (also known as a thimble) to connect the cheap black single-walled stovepipe coming out of the stove to the stainless chimney pipe. The thimble mounts to the ceiling. Once you go through a ceiling or wall, you MUST use insulated stainless double-walled pipe for the rest of the installation.

A through-the-wall installation is similar but usually more expensive as the stainless pipe run is longer.

Usually, a through-the-ceiling installation results in better airflow and draft, making firelighting easier and reducing back-puffing when reloading the firebox.

For a single-story installation, figure close to $1000 for a high quality stainless chimney kit.

I found the best price at Woodstock Soapstone stoves:

http://www.woodstove.com/

My installation kit ran $970.

There is much info regarding installation available online at the Woodstock website and ANYONE who answers the phone there can tell you exactly what you need. They'll even take the measurements of your house & hearth and figure out how much pipe, etc. you'll need. The woman who took my order gave me precisely enough pipe to do the job correctly but not one foot extra.
I recommend them highly.

Make certain to maintain the specified clearances to flammables.

Also, be aware that in many areas your woodburner installation will require a building permit and an inspection. Where I live, in South Jersey, if you fail to have the permits and inspection and your house burns for any reason, the insurance company is off the hook.

Above all, be safe.

Hope this helps.

Answer 3

If none of the flue chimney is not cracked & has a place at the bottom to use as a clean out, it will be fine to use as a wood burning chimney, just get it inspected.A new steel chimney installed would cost $ 800 - $1500 bucks Can., U can put a small Dia. 6'' liner up a flue chimney