Effect of reducing size of stovepipe

[Chandra]

I just purchased a Jotul F400 for my 1350 st foot home with cathedral ceilings up to 20 feet high. The installer reduced my 8 in wall stovepipe to 6 inches the bottome 2 feet of the pipe. The stove smokes a lot. It doesn't heat the house even bringing the stove up to 600 degrees. The store refuses to upgrade me to a larger stove unless I replace all my pipe with 6 " single wall. Why will I get less smoke and better draft with the smaller pipe. The flue opening on this non-catalytic wood stove is 6 inches.
Another installer wants to install double wall all the way through the ceiling which will cost $1300. Is this really more efficient?
I heat totally with wood. I get snow and cold weather and like to make as goood fire. Isn't single wall more apt to create a flue fire. If I upgrade to a larger stove won't the additional heat from the stove make up for any loss of heat due to double wall.

 

[kevinmoelk]

Wow, you've got about 5 different questions here. I'd strongly suggest doing a lot of reading around here.. I think you'll find many answers to your questions and clarifications on some of the terminology you are using.

I've just finished my install, and I'm a frugal man. Still the cost will be roughly $1400 when all said and done, with a used stove. It's not necessarily an inexpensive proposition, but I think you need to look at as an investment. On the same note, having the correct chimney set up not only will make you happier as the stove will run better, but give you peace of mind knowing things are safe.

 

[Hogwildz]

I just purchased a Jotul F400 for my 1350 st foot home with cathedral ceilings up to 20 feet high. The installer reduced my 8 in wall stovepipe to 6 inches the bottome 2 feet of the pipe. The stove smokes a lot. It doesn't heat the house even bringing the stove up to 600 degrees. The store refuses to upgrade me to a larger stove unless I replace all my pipe with 6 " single wall. Why will I get less smoke and better draft with the smaller pipe. The flue opening on this non-catalytic wood stove is 6 inches.
Another installer wants to install double wall all the way through the ceiling which will cost $1300. Is this really more efficient?
I heat totally with wood. I get snow and cold weather and like to make as goood fire. Isn't single wall more apt to create a flue fire. If I upgrade to a larger stove won't the additional heat from the stove make up for any loss of heat due to double wall.

What part of the country are you in Chandra?

 

[kevinmoelk]

Just re-reading... 20ft tall ceilings?! Wow, what is your temperature up there Chandra? How are you moving your air around? Do you have ceiling fans? My last post isn't meant to be harsh mind you, we are here to help and there are many great folks on the forum. Much smarther than myself on the subject, lol. Welcome to Hearth.

-Kevin

 

[precaud]

The store refuses to upgrade me to a larger stove unless I replace all my pipe with 6 " single wall. Why will I get less smoke and better draft with the smaller pipe. The flue opening on this non-catalytic wood stove is 6 inches.

Your stove is designed to work with a 6 inch chimney pipe. With the 8 in pipe you have now, the exhaust travels through the pipe more slowly, thereby cooling more quickly. I know it sounds counterintuitive, but both of those factors reduce your draft. If I were you, I'd go with the 6 inch.

Another installer wants to install double wall all the way through the ceiling which will cost $1300. Is this really more efficient?

Depends what you mean by "efficient." If you mean "all the way to the ceiling," it sounds like overkill to me.

Isn't single wall more apt to create a flue fire.

Not unless you're careless with how you operate your stove.

If I upgrade to a larger stove won't the additional heat from the stove make up for any loss of heat due to double wall.

Now that is not what I would call an "efficient" solution...

 

[elkimmeg]

The forum deals with simmilar questions at least 5 times a week. I'm guessing here, you replaced an older stove that burnt quite a bit of wood and burned hot?
The stove you purchased should do the job. You have to adjust your burning habits, to the draft sensitive modern stoves. Todays stoves are geared to be run 24/7.
and to burn longer at 600 degrees. If you are use to fast heatups and chances are you were close to overfiring. The modern stove is not for you. If willing to modify your burning habits
and burn 24/7 the accumulation of heat will accomplish the task at hand. That will mean learning how to damper down into secondary burning process. It will also mean to load the stove less frequently ie less opening the door and less smoke escapage. You will have to learn to open the air crack the door first then slowly open it for re-loading. Once you have achieved the start of second phase burning, closing down the damper and initiating the secondary burn process.

BTW welcome to Hearth.com

 

[Hogwildz]

I'm still wondering why they told him/her they need double wall inside the house? Thats a waste of cash to me. Now throught the ceiling & outside, sure thing, but inside conditioned area? Looks like a money monger to me giving the quote.

 

[EatenByLimestone]

If he has 20 feet of single wall couldn't he loose enough heat to really slow down the flow?

 

[elkimmeg]

I'm still wondering why they told him/her they need double wall inside the house? Thats a waste of cash to me. Now throught the ceiling & outside, sure thing, but inside conditioned area? Looks like a money monger to me giving the quote.

I agree if he/she can achieve 600 drgrees it sounds like the draft is working quite well. I agree it sounds like over kill at a hefty price. lLke changing all new spark plugswhen one is faulty.
He/she has to learn how to opperate a modern stove 24/7

 

[BrotherBart]

You say ceilings "up to twenty feet". How tall is the actual single wall pipe you have connected to the stove?

 

[wahoowad]

Your room with the cathedral ceiling is probably going to retain a good bit of your heat. A ceiling fan (which you probably already have) will help but I'm betting you will not get adequate airflow out of that room to suitably heat your whole house. A lot depends on the openings between this room with the cathedral ceilings and how the ceiling flows throughout the rest of the house. Tell us more about your house.

How long have you been a woodburner?

Pictures help.

 

[Chandra]

Thanksk for your response. I have made fires for 30 years. My last stove was quite large and burnt lots of wood, about 3 to 4 cords each winter. It heated well but the fires wouldn't last overnight. Now I have pretty much decided to go with the double wall since it will last longer. I have had the present 8 inch double wall for 30 years. I understand this Jotul is designed to work best with 6 inch pipe. Presently on the JOtul F400 the 6 inch goes up 2 feet of single wall and then 8 inch double wall to the ceiling and above. I wish to upgrade to the Jotul CBfirelight. My hoouse is 1350 sq feet. One large living room and kitchen, with two bedrooms off of that plus to small bathrooms. THe store is only willing to upgrade me to the firelgiht if I change my stove pipe. He also thinks its overkill. My installer says if I don't overoad with wood I can make smaller fires without creating a lot of creosote.

Thanks for your input.

 

[webbie]

Sounds like your existing chimney is also too short, therefore a lack of draft. That stove should do the job.

30 year old metal chimney - time to replace it.

The fact that it is 8 inch is not as important as the fact that it is too short, or that it is probably triple wall (air-cooled) older pipe which stays relative cold. With a straight up chimney like that, I would suggest a total height of at least 14 feet from the stove to the termination...or taller.

As others have said, a smaller pipe stays warmer and therefore drafts better.

 

[Chandra]

Once again, thanks for your time in responding. This is my first forum experience and I am most grateful for all taking the time to try to help. I am a female yogini living in the beautiful Sierra foothills in Tuolumne County. I enjoy wood fires and all the preparation to be able to enjoy its warmth.

However, I am still not clear about the following. Some informationis repetitious so if you are familar with my situation just skim over it.

The present stove is a Jotul F400. I have no question that it is too small. My house is 1350Square feet. I plan to upgrade to a Jotul CB firelight which heats up to 2500 sq feet due to high ceilings and drafts and cold. My house has drafts especially around the doors. It is diffiucult to heat the bedroom and office off the living room. THe high ceilings go from 20 feet to 12 feet. This present stove, Jotul F400, now has about 16 feet of interior stove pipe. It is double wall interior and exterior except for the lower 2 feet that connect to the 6 inch flue opening. The lower 2 feet are single wall.

Is it correct that the larger pipe negatively affects the needed draft for the fire? How does larger pipe create less draft?

Is it correct that when stove pipe is that long it is better to use double wall? I do not need double wall for clearance requirements since the stove sits in the middle of the room.

When I don't want a large fire, and when I have the larger Jotul, the CB firelight, will I be able to just add less wood and then crank the draft control down? Will this prevent smoke and therefore creosote buildup?

Thanks again for sharing your wisdom.
Is it better to

 

[webbie]

Yes, the larger pipe makes for less draft. It does this by cooling the smoke. Cooler smoke does not rise as quickly as hotter smoke.

Yes, 16 feet of interior single wall is too much. You can use some single wall if you like, perhaps 6-8 feet and then transition to double wall if you like.

As to the third question, be aware that it is the opposite of what you imply. A larger stove turned way down creates MORE creosote! Creosote is formed when wood is burned in the absence of enough air and when the temperature is too low in the firebox to properly burn the wood gases. These gases, when not burned, are what settles as creosote.

You are correct in that adding smaller amounts of wood is the proper way to control a fire in warmer weather. This is much better than a larger load with reduced air.

The good news is that newer stoves burned in any decent fashion will not create creosote problems.

As to stove sizing, with that height of a ceiling you should be fine with the larger 500 or firelight....I'm keeping in mind that you are probably burning softwoods, so the stove is not effectively as large (not as many BTU's will fit in the firebox) as here in the east.

Good luck!

 

[kevinmoelk]

Chandra, you mention drafts around doors. How are your windows? Also, have you considered an OAK? Controversial subject around here, but I have an old leaky home and an OAK. For experimentaion purposes I have played with disconnecting the OAK and plugging the fresh air intake so the stove would be drawing in room air. To me there is a huge difference of air sucking past my old windows while combusting warm room air. When the OAK is attached, the windows are far less leaky. My 2 cents.

I strongly suggest you seal up some of the cracks and gaps, regardless of whether you use an OAK or not. It will only make the home that much more efficient. The $100 bucks you spend on weatherstripping, silicone, and spray foam will easily pay for itself in the long run. Over time upgrade your windows and doors, and that will make a huge difference too.

-Kevin