Woodchuck Wood furnace - 8" to 6" flue? - See pics.

[Drifthopper]

Woodchuck Wood furnace - Model 4000

I recently purchased a WoodChuck Wood furnace, Model 4000 and in the process of installing it in my basement.
It was used, the guy I got it from removed it and was going to a pellet furnace.
From the info I got, it’s about 15 yrs old, its from 1993, but its in very good condition, inside and out.

I’m just setting it up now, still have to get firebricks for it, and a plenum made up, He gave me the manual for it, and i've been on on-line trying to read up what i can, but any tips or info I should look out for???

One of the first questions I have, it has an 8” flue coming out the back and my flue opening in the basement wall is only 6” .
My friends that came over to help move it in the basement (its one heavy unit) said I can just get an 8 to 6 reducer.
I’ll have to do that, but is it best to have the reducer close to the stove, say as soon as it exits out the back or should I run 8” out the back then reduce it down right before it goes into the basement wall?
From the back of the furnace to the wall will only be about a 42” – 48” run. I'll have an 8" rise from the back of stove to the flue in the wall.

Also, i have read a lot about putting a damper in the stove pipe, It’s a forced draft furnace and where the draft comes into the fire box so it is suppose to be air tight, but not sure if having a damper will help extend my burn times.

 

[slowzuki]

First, by code you shouldn't be using any reducers.
Second, you definitely shouldn't install a damper on a forced draft appliance.
Third, because it is forced draft you may be able to make it work with a 6" flue but the insurance man and building inspector will not like it!

 

[webbie]

I think that company is still in business - Meyer Manufactuing?
(broken link removed to http://www.meyermfg.com/woodchuck.html)

As stated above, you should try to use as much of your chimney size/capacity as you can. If chimney is 7" square inside, perhaps you could at least install a 7" ID crock?

As enord says, we are speaking practically only......in terms of code, only the manufacturer or your local inspector can OK something that is not expressly in the owners manual.

 

[Drifthopper]

Well..this thing is not coming out and I’m not going to open up the flue …so Slow, your suggesting coming off the back of the furnace with an 8” “tee” then a 8” straight, then 8” elbow, then reducer, then out thru the wall….that’s the way I understand what ya typed.

Or…for others reading…what about : 8” tee out the back, 8” pipe, then reducer, then 6” elbow, then out the wall. How would that be?

Web…..i’m just looking for suggestions to make this thing work,,,,so I’m not really following ya as for “practically” speaking…..?????

 

[webbie]

Practical means just that - there is no "right" way of reducing from an 8 to a 6", there is a reason that the furnace has a 8" flue......this is nearly a 50% reduction in capacity.

So anything we tell you is contrary to the manual, manufacturer and UL listing on the furnace - unless, as I mentioned, it is OK in the manual or by the manufacturer.

I just looked and that is the largest furnace they make! That makes the reduction every worse! What you are trying to do is to place a large engine into a tiny exhaust. Depending on the chimney height, it probably does not have the capacity for the number of BTU's you are going to put into it.

So, short and sweet, I would say that our recommendation is to not do it - which does not appear to be advice you are willing to take. If you do it, there is not right way!

While we often give advice to make something "grey" work, this is not one of those cases....from afar it sounds really far off.

BTW, assuming your flue is nice and tall, etc - it is not vary hard to replace a crock in the wall. You can rent a small demo hammer for about $35. and it will not take much time.

 

[JustWood]

I have the smallest woodchuck and love it. I heat 1600 sq. ft. and even on nights -20 below it does an excellant job heating the house. Because of their design (similar to OWB's with the forced draft) they stay "choked" down when heat is not in demand. I found over the last 3 years of operation that it requires really dry wood or I start having bad creosote problems. IMO I think that unless you have a very large house with huge heat demand that you will have severe creosote problems choking it down to 6". You could try it and see what happens but be prepared to resize your flue . Good luck , you made a great buy with the woodchuck.

 

[begreen]

Why not "open up the flue"? It would take maybe 15 minutes to demolish the 6" clay thimble. Maybe another 60-90 minutes to increase the opening to 8" and cement in a new 8" thimble. My thought is to do it right once, than do it half-right first, then right afterward. I'd prefer to have the furnace working right as the manufacturer specified than to second guess it's operation and maybe problems afterward. My advise would be to get over the inertia and do it right the first time.

 

[elkimmeg]

You are telling him what he does not want to hear he is going to do it anyways without doing it correctly and without a permit of inspections.
I dealing with a similar situation now where the FD had an incident and called me in to investigate No permit no inspections the guy refuses to remove the unit
each day the fine m adds up its $1000 each day for each violation. So far that illegal installation has cost the guy $32,000 in fines. Eventually we will have to take him to court and he will be assessed the fines. I have done every thing in my power to get him to comply but he refuses. Now the courts will decide and he does not have a leg to stand on. I begged him not to force our hand. The fire DEpt was there because of the stove caused the fire and they have been there in the past, again a fire caused by the stove The FD commended it the first time. Now it our turn to deal with it. all it takes is one fd incident or a complaint about smoke and you will not be so cavalier about scoffing doing it right.

 

[Drifthopper]

Elk…..BS! …..I’m looking for options…I’ll entertain all possible alternatives, I’ll listen to whatever is suggested, ….if there is no way around this…then I’ll do what’s gotta be done….from the guys I talked with around here…They’re like…”Ah…just reduce it” ….i didn’t think it was this big a deal….Sorry.

Lees Wood….the guy sold me the whole set up for $125.00, with a couple cans of hi-temp paint and buying new fire bricks,,,I’m probably into ….maybe $200.00 max.

Web…..What’s a “crock”? BeGreen….”thimble”..???? Huh..?? I’m not up on the proper terms / wording.

I’m just running out of time…..I was leaning toward the Englander 28-3500, then this came up in the pennysaver, and I couldn’t pass it up, I'm just trying to get it to work.

 

[Drifthopper]

Elk…..BS! …..I’m looking for options…I’ll entertain all possible alternatives, I’ll listen to whatever is suggested, ….if there is no way around this…then I’ll do what’s gotta be done….from the guys I talked with around here…They’re like…”Ah…just reduce it” ….i didn’t think it was this big a deal….Sorry.

Lees Wood….the guy sold me the whole set up for $125.00, with a couple cans of hi-temp paint and buying new fire bricks,,,I’m probably into ….maybe $200.00 max.

Web…..What’s a “crock”? BeGreen….”thimble”..???? Huh..?? I’m not up on the proper terms / wording.

I’m just running out of time…..I was leaning toward the Englander 28-3500, then this came up in the pennysaver, and I couldn’t pass it up, I'm just trying to get it to work.

 

[BrotherBart]

"Crock" and "thimble" are the same things. The orange clay thing sticking out of your wall that goes into the chimney. The guys are right. Open that thing up and put an eight inch thimble in it and seal it up. Be sure when you do that the new thimble only extends into the chimney tiles even with the interior of the tiles. Not sticking out into the chimney.

Folks here will give you detailed instructions how to install it correctly and safely. You saved a ton on the heater. You can spend a couple of bucks for a proper installation.