# wood stove and chimney question



## [email protected] (Feb 24, 2005)

We want to get a wood stove in finally. According to the chimney/wood stove guy we consulted an 8 inch flue would be best. All we can find our wood stoves with 6 inch stove pipe openings and no one can tell us if that can be sized up to an 8 inch flue or if that means we will have a 6 inch flue. Chimney guy is not available to contact right now, people at places like Lowes don't know anything about it because they don't install the stoves. 

What should I be looking for in a wood stove to make it meet the chimney guy's suggestion, he says with a smaller flue we would have to have the chimney lined but with a bigger flue we won't. 

We are trying to keep the cost down if possible as much as I would love a really nice looking stove like Vermont Castings they aren't in the budget. We would like a window so we can see when wood needs to be added plus I like the way fires look. It's not a necessity but I would like it. 

We are looking for a bigger door opening so we won't have to split wood as small. Any suggestions?


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## Ken in Maine (May 10, 2002)

You should be able to purchase a 6 X 8 increaser/reducer that would go in the stove pipe just before it goes into the flue...


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## Qhorseman (Jul 9, 2010)

Use what you woostove manufacturer suggests. The stove is designed to draught with a certain size flue. any bigger or smaller and you will not get proper draught for the stove.


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## [email protected] (Feb 24, 2005)

Is that going to let enough heat into the chimney to keep the creosote down? I guess that is the main reason to need an 8 inch flue but I can't figure out if using the increaser will work for that. 

Thanks for the help, I appreciate you taking time to respond.


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## artificer (Feb 26, 2007)

Combustion in wood is in two phases. Volatiles get boiled off, and if they aren't burn, become creosote when they condense. A good hot modern stove will add secondary air to burn these gasses, and increase the efficiency. Its one of the reasons burning green wood is so cold... the temps don't get high enough to burn the gasses, so you lose half of you potential heat. The other way to keep creosote from forming is to prevent condensation in the flue. Insulated chimney pipe will help with that. The insulation will also help with draft. If you use insulated double wall pipe, then the 8" shouldn't cause any problems, even if your stove has a 6" outlet.

Follow the stoves recommendations for diameter over the "stove guy's" suggestion. They designed it... they should know how it works.

(The second phase of combustion, btw, is the charcoal thats left.)

Michael


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## Qhorseman (Jul 9, 2010)

use an insulated flue pipe and you will be fine


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## Harry Chickpea (Dec 19, 2008)

The maker knows best, as usual.


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## Waterwheel Farm (Oct 10, 2011)

An 8" flue would probably be best. You can install an adapter on a 6" stove to an 8" flue with no problems. However, if you eventually get a stove with an 8" outlet, you might have problems getting it to draw right restricting it down to a 6" flue. One of my stoves has the glass front, which I enjoy seeing the fire too.


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## mekasmom (Jan 19, 2010)

We used a converter for years and years with our wood stove with no problem. We bought it way back in the 80s for eleven dollars to go from a 6" stove to an 8" pipe. It's just about six or eight inches long and fits from the stove to the bigger pipe.


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## [email protected] (Feb 24, 2005)

Thanks for the advice everyone. It is much appreciated. I wanted to be sure we do the right thing so we don't have to redo it. We will be studying the manufacturers instructions to make sure we have it right.


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## DeRock (Feb 22, 2011)

If you care about such things a wood stove needs be be installed exactly as the stove manufacturer specifies to be building code compliant. Most insurance companies will not insure you if you don't get a mechanical permit and inspections.

Most stoves of recent manufacture have a plate fixed to the stove that will have important information about clearances to combustible materials (back, side, top, and bottom).

There a several new stoves that have windows in the front that are reasonably priced. Around here (Michigan) you can find them at Menards. They are more modern in design than Vermont Castings though.

I would look at used stoves if you are trying to stay within a budget. Stoves like Vermont Castings sell for thousands of dollars new but you can find them used on Craigslist for several hundred dollars.

I guess my question to you is what do you hope to accomplish with a wood stove? Are you looking to heat your entire house or just something pretty to look at. Your answer will dictate what you should be looking for in a wood stove.


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## Wolf mom (Mar 8, 2005)

While you're at it, look at installing a Magic Heat Reclaimer or similar product. The difference in pushing heat with & without it is amazing. There's a similar product that doesn't use electricity, but I don't think it works as well.

http://www.buzzillions.com/reviews/magic-heat-reclaimer-wood-coal-or-oil-heaters-reviews


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## jwal10 (Jun 5, 2010)

Newer stoves need to run hotter so they use the 6" pipe, build big hot fire then damper down to conserve wood. The 8" flue cools too much, this condenses the water and creosote vapors. Might work with a bigger stove, some use 8" pipe. If it were me I would size the stove you want and need and line the flue for the best results....James


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## Cabin Fever (May 10, 2002)

[email protected] said:


> ....he says with a smaller flue we would have to have the chimney lined but with a bigger flue we won't...


Based on this comment, I assume we're talking about a concrete block chimney. I say this because there is no such thing as lining/not lining a metal chimney. A chimney block with an 8x8 opening is what one would use of a stove with a 6" flue. If the stove has a 8" flue, one uses a chimney block with a 8x12" opening. In either case, ALWAYS-ALWAYS-ALWAYS line a concrete block chimney with a clay liner!



[email protected] said:


> ....We are looking for a bigger door opening so we won't have to split wood as small. Any suggestions?


Chimney/flue size is dictated by the door opening area. Stoves with large door openings require a 8" flue, stoves with smaller doors require a 6" flue. The reason for this is so the stove doesn't smoke into the room when the door(s) is open. If doors were always closed on woodstoves, all any of them would need is a 6" flue.


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## ET1 SS (Oct 22, 2005)

Does your home have Radiant Flooring? Or baseboards? If so you may wish to consider woodstoves that heat water. So you could then circulate heated water through your radiant floor system or baseboards.

We have radiant flooring and our woodstove heats water that circulates through our floors.

It gives direct radiant heat in the area around the stove, and it also gives warmth through out the house. 



If you end up with a stove that has a 6" outlet, then you will need a 6" stove pipe. I would not try to adapt that up to 8".



Our stove-pipe is not insulated. It is single-wall pipe. We have not had any problems with creosote fires. But then we do not allow any combustibles within 3' of the stove or stove-pipe. And we have a metal roof.


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## CarolT (Mar 12, 2009)

I'm not sure I understand completely what the problem is? We had a 8" flue and the stovepipe was 6". Stovepipe leaves the stove, goes into a thimble through the wall and empties into the 8" flue. Is yours going straight up or sideways when it leaves the stove? Be sure to understand exactly what he's recommending. Also, be sure the flue goes far enough past the top of the house or it won't draw well.

ETA The flu was the red clay flu with chimney blocks around it.


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## ET1 SS (Oct 22, 2005)

CarolT said:


> I'm not sure I understand completely what the problem is? We had a 8" flue and the stovepipe was 6". Stovepipe leaves the stove, goes into a thimble through the wall and empties into the 8" flue. Is yours going straight up or sideways when it leaves the stove? Be sure to understand exactly what he's recommending. Also, be sure the flue goes far enough past the top of the house or it won't draw well.
> 
> ETA The flu was the red clay flu with chimney blocks around it.


The output from the stove is X big, if the stove-pipe is smaller then that it may restrict draft flow.

If your stove output was 8" and you stuck a 6" stove-pipe on it, there is the possibility that the smaller stove-pipe may restrict the flow of smoke.

The closer to vertical the entire process is, combined with how long [in vertical measurement] the stove-pipe is; determine how strongly it will try to draft when it is heated.

By being 4' above the roof peak, you get the added benefit of venturi-forces pulling the exhaust out from the stove-pipe.

A 4" vertical stove-pipe can only draft a maximum of so much volume of exhaust. Whereas a 6" vertical stove-pipe can draft a higher volume of exhaust; and a 8" vertical stove-pipe can draft an even greater volume of exhaust.


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## CarolT (Mar 12, 2009)

Yes, but they said flu, not stove-pipe. That's what I was asking. If you vent through the wall into a flu, it's different than venting straight up through the ceiling. If you vent through the wall into the flu, there's no need to adapt from a 6" stovepipe going into the flu


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## Waterwheel Farm (Oct 10, 2011)

The main thing is to install your flue correctly and safely. That is not the place to save a few pennies, even if you do the flue this year, then get the stove next year. Plenty of advice to use a certified installer, or follow manufacturers recommendations. I tried that when I wanted to install a wood stove in my last double-wide. I ran into stuff like this over and over:

Me: "Who installed your stove and flue?" 
Them: "My cousin Billy Bob"
Me: "Oh cool..thank goodness! Finally! Someone certified! Can you give me his number?" 
Them: " He doesn't do it any more. But if you even need a septic system installed or gutters, let me know. I can get in touch with him."

I ended up doing it myself following the instructions that came with the flue pipe and stove. Insurance inspected, OK to go and I felt pretty good about it.


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## ET1 SS (Oct 22, 2005)

CarolT said:


> Yes, but they said flu, not stove-pipe. That's what I was asking. If you vent through the wall into a flu, it's different than venting straight up through the ceiling. If you vent through the wall into the flu, there's no need to adapt from a 6" stovepipe going into the flu


Okay what is the difference between a flue and a stove pipe?

A flue is a duct or pipe, for conveying exhaust gases from a fireplace, furnace, water heater, boiler, or generator to the outdoors. It can be is 4", 5", 6", or 8" diameters.

You may wish to connect to 45degree or 90degree elbows of piping to get the right angle you need. Before finally going straight up.


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## CarolT (Mar 12, 2009)

Guess it's different in my neck of the woods, sorry.

Here a flue is the red clay liners inside concrete chimney blocks _outside_ a building. A stove pipe is the metal pipe that comes out the back of the stove, if it turns and goes up through the roof, it stays a stove-pipe. One of those things I didn't think to check other people's definition before saying something


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## Fae (Mar 9, 2005)

My Lopi Endeavor has 6" stove pipe going into a 6" clay thimble that goes into clay flue liners in a brick chimney. Works great.


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## meanwhile (Dec 13, 2007)

Try reading and learning from some of these sites. When we put in our last wood stove, I found it very helpful to know as much as I could before deciding on a stove and especially the insulated pipe and chimney. Good luck - be safe.

This web site has good links to learn about pipes and chimney:
http://www.etowahfireplace.com/stove_pipe.html

Read this about the insulated chimney:
http://www.mtlfab.com/media/L898.pdf#page=2

You can read more here:
http://en.allexperts.com/q/Chimney-Fireplaces-3286/

Good luck.


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## artificer (Feb 26, 2007)

CarolT said:


> Guess it's different in my neck of the woods, sorry.
> 
> Here a flue is the red clay liners inside concrete chimney blocks _outside_ a building. A stove pipe is the metal pipe that comes out the back of the stove, if it turns and goes up through the roof, it stays a stove-pipe. One of those things I didn't think to check other people's definition before saying something


It may be regional differences, but in my area (Wisconsin) "stove pipe" is a single wall pipe, typically black. You have to switch to some other type of pipe to go through the wall or roof. 

Flue is any vertical pipe that acts like a chimney. It can be flue tiles in a block chimney, SS flex liner flue liner for a block chimney, or just the double/triple wall insulated chimney pipe.

I like to use the insulated chimney pipe because it tends to draw better. Easy to install, legal if you follow the directions...

Michael


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## ET1 SS (Oct 22, 2005)

artificer said:


> It may be regional differences, but in my area (Wisconsin) "stove pipe" is a single wall pipe, typically black. You have to switch to some other type of pipe to go through the wall or roof.
> 
> Flue is any vertical pipe that acts like a chimney. It can be flue tiles in a block chimney, SS flex liner flue liner for a block chimney, or just the double/triple wall insulated chimney pipe.
> 
> ...


Here double-walled or triple-walled is only needed if it is passing near combustible material.

Are you saying that your vertical pipe 'acting like a chimney' can not be single-wall pipe?

Does your vertical pipe have to be ceramic tile, or SS flex liner, or double/triple wall insulated chimney pipe?


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## artificer (Feb 26, 2007)

ET1 SS said:


> Here double-walled or triple-walled is only needed if it is passing near combustible material.
> 
> Are you saying that your vertical pipe 'acting like a chimney' can not be single-wall pipe?
> 
> Does your vertical pipe have to be ceramic tile, or SS flex liner, or double/triple wall insulated chimney pipe?


I said "Flue is any vertical pipe that acts like a chimney." That includes black stove pipe. The problem with black stove pipe/single wall uninsulated pipe is the distance it needs to be kept from combustibles. You can also use it up the side of a building, like I've seen people do with shops/sheds/barns, but I wouldn't suggest. I should have used "channel" instead of pipe, but that just sounds silly to me.

Michael


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## ET1 SS (Oct 22, 2005)

Just trying to understand how a 'flue' differs from stove-pipe or chimney.

Sorry about the confusion.

I certainly agree that we all need to be safe, and keep combustibles from igniting.



May God bless you.


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## [email protected] (Feb 24, 2005)

Thank you for all the help and advice. I think we have more studying to do because the whole chimney/flue thing is still not clear to me. The installers terms not what any of you are saying. I'll have him clarify it for me.


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## CaveMole (Feb 24, 2021)

Waterwheel Farm said:


> An 8" flue would probably be best....


My brief internet research agrees. I see recommendations for top flue section to be between 25% larger area than stove pipe, but not greater than 3x the area. That would make a 6.7" flue minimum, but 8" is the next standard size. 10" would be 2.8 times the area of a 6" pipe, so that would be the max before causing draft problems.


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## Danaus29 (Sep 12, 2005)

Thread started in 2011, poster quoted hasn't logged on since 2014. By now the original poster either has the chimney installed or dropped the project.


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