Installing a wood furnace.......Chimney trouble!!!

Thanks!!!

No quick, easy answers here. You are asking to deal with very complex variables that only experiance can answer. Buy the book, (or just read the important parts in the book store): "Renovating Old Houses" by George Nash, published by Taunton press. He covers in detail your specific questions and how to "do it yourself". This book will save you pain and suffering and cash. You can line the chimney with tile and vermiculite and get by nicely this year until you can build yourself a new chimney. Forget wood furnaces, (if it was any good, why would some dude give it away?). Install a wood stove instead. Get the heat directly. Most self styled experts are damn fools and will turn you into one too and take your hard earned bucks in the process. Don't be scared, but don't be stupid either. Keep the new chimney inside the house so it will draw properly. Best of luck. Jared

The stainless steel chimney liners cost $25 a foot, or at least they did a few years ago. Not hard at all to snake them down inside the old chimney yourself. Available at woodstove specialty stores near you. All manufacturers insist their metal pipe will withstand chimney fires without damage, but then also insist that the pipe must be replaced if a chimney fire occurs. They are all rated for a life of around 10 years or so. The latter is often times well buried in the fine print btw.

Insulating a lined chimney is an interested area with many different arguments and rationals.

There is the camp that says it's completely unnecessary. That the pipe will be fine sitting free in the old chimney That this allows some heat to get into the chimney and warm the house. That it allows the metal pipe to expand and contract. That if the pipe should leak exhaust gasses, they will freely exit up the chimney. That insulation may result in the pipe being crushed, particularly the lose vermiculite. Vermiculite packs down, and can crush the pipe at the bottom if the chimney is tall. Add in water if it can it into the chimney and you increase weight, as well rust issues, and if it freezes, the crush becomes more severe.

Those that are pro insulation are also of two camps. The liquid mortar and the vermiculite and other lose fills. Claims of sealing the chimney should the pipe leak, protecting the occupants from combustion gasses. Protection from vermin entering the chimney. Increased (or decreased) thermal conductivity to the old chimney. Ease of installation (particularly the vermiculite proponents).

Future repairs with either mortar or lose fill insulation is difficult to impossible. With the mortar, it's effectively impossible. The lose fill can be dropped out the bottom of the chimney and repairs to the pipe made.

Many chose to abandon repairs when the chimney has been solidly insulated, treating the insulation as the chimney. This does seem to work, but many of the mortars dissintegrate when in direct contact with the acids of combustion gasses.

So here's my story and decision.

My house has two 4 story brick chimneys internal to the house, one on each end of the house. One used by the oil furnace, the other by the wood stove. Neither is in any danger of falling down, but both have poor mortar joints. The woodstove chimney has a teracotta liner, but it was installed improperly with conventional mortar in the joints, which has all been eaten away.

I went with uninsulated metal pipe dropped into the existing woodstove chimney. The ability to inspect both sides of the pipe, the ability for gasses to rise outside the pipe should it happen to leak, the ability to make future repairs easily, and the cost of not buying insulation were all factors in my chosing the non-insulated route.

The choice of pipe I made was black stove pipe. The exact same pipe you use between the stove and the wall thimble. My reasoning was that this pipe is perfectly adequate as a chimney pipe, for that is what it is. It is not as long lasting as stainless, but it is cheap and easily replaced.

I installed it from the top, with the 4' sections screwed together. It was actually quite easy to do this job. The pipe is doubly mounted in that it sits on the 90 degree elbow at the bottom, and is suspended at the top from a rod going through the pipe and resting on the chimney top.

The total cost of my metal chimney liner is only approximately $100.

This has given me a secure metal chimney that I can (and do) easily inspect and clean on a routine basis. It has been in service for several years now, and has worked very well. I do have a CO monitor in the house, and it's readings have always been negligible during times I'm using the woodstove.

I did talk to my insurance agent about this prior to installing it. My existing brick chimney was legal and I was allowed to use it. As such, my lining the chimney was an enhancement to the already existing and legal chimney. The insurance representative thanked me for doing it, and as I recall, I got a small percentage discount on my policy for doing it.

You can have a special cement stuff poured down thew chimney around inflatable tube to give it a real good lining.

You can line the current chimmney with metal.

You can put a triple wall metal chimney up outside the house.

That is best to worst options. If you really use the wood burner, you will save money with any of those options. Do this chimney thing wrong, and you will cost yourself a lot of money, & perhaps a life or 2.

Wood ash & heat is really hard on metal. You"ll be looking at doing it again in 10 years if you pick either of the metal options. Your call.

--->Paul

Get a pro to look over the entire situation. I've seen installations like Pete mentioned. It meets code, is effective, and you better buy a winning lottery ticket! The pro might also suggest placing the wood furnace on an outside wall and running a class "A" (triple wall insulated) chimmney through the wall and then up on the outside, and then above the roof. This is not a perfect solution but does work. It also ain't cheap. There are other alternatives as well.

You may not realize this but a decent wood furnace, proper chimmney, and professional installation can easily eat $3,000 - $5,000 in a heartbeat. Anything less and you have a very good chance of burning the house down.

An alternative is an outside wood furnace. It pipes the heated water into your house and then you use an air handler/heat exchanger to move the heated air. Very safe but you'll spend $8,000 - $10,000 (installed) at a minimum.

I"m with Pete as you can"t do this job on the cheap or it"ll kill your family in a heart beat.

Just think of a 6" flue on fire 14ft high burning at close too 3500�f at about 2000ft/sec.

Big blow torch huh! If the flue is not installed correct thats just what you"ll have, a huge blow torch!

I tried to tell my Dad how to install his flue and he wouldn"t listen to the "kid". The 2nd winter he burnt the rafters and wall studs out of the corner of the livingroom.

The inside stack to the thimble got so hot it melted the pipe. About $4k in materials alone and of course it was the wood stoves fault, not his :>)

T_Bone

Yep, same thing my Dad did, load the box with green wood with alot of sap, start the fire and dampen the flue as soon as the fire started.

This caused creosote to build up on the flue walls 1/2" thick and when the creosote caught fire it burnt off in chunks from the steam (not enough water at one time) then shot out of the stack like a cannon.

This is my 16th year on my current chimney. I awlays start a fire letting it burn as hot as it can get for the first 20min as this burns off any creosote build up from the previous day(s) use.

In 16yrs I"ve never had to clean the flue. I do take the chimney apart each year for inspection.

T_Bone

I"ve heard of putting an aluminimn can in the fire box every once in a while, have no clue if it actually does anything.

They make a product you toss in the flame every few weeks, one for wood, one for oil burners, to take down the coatings some.

--->Paul

I would think salt would be super corresive?

Wood ash and water make lye so throwing in some salt should really eat up some metal...lol

There was a product called Red Devil or Blue Devil (I have no idea what it was) that looked like copper sulfate, that when added to the fire would also cause cerosote not to stick to the flue wall.

My kids like watching the flame when I added it as it would change the flames all different colors.

T_Bone