Stove Size and Flue Size 5K Sq Ft Multi-Story

[ShenKen]

Hi! I'm pretty new to the forum, although I have been reading some discussions for awhile. We are building a new house in central Virginia and would like to provide for a free standing wood stove in the basement. I grew up in a house that had a large wood-burning furnace and have wished for years to have a wood stove again.

My main question at the moment is what size chimney to put in, but of course the size of the stove plays into that.

The total square footage of the house is approximately 5,000 (basement 2,000 + main 2,000 + upstairs 1,000). Ceilings are 9 ft in the basement, and 8 ft main and upstairs.

We plan for the stove to sit in the basement family room, near an exterior wall. The chimney will be a straight run of Class A pipe up through the interior of the main floor and upstairs, then on up inside an insulated chase. Total chimney length: 25 ft +/-.

I was planning on an 8" ID chimney to make sure I'd have enough draft, and I have room for an 8"; but in talking with various people I have been cautioned that too LARGE a chimney can lead to reduced draft and creosote build-up.

But IF we would go with a 6" chimney and be wanting whole-house heat from the stove, could we expect to get it from a stove with a 6" collar?

Also, considering that the chimney pipe is mostly inside the insulated building envelope (meaning the chimney will stay warmer), will that help with creosote issues?

Any advice will be appreciated. I'm essentially a newbie since I haven't ever owned my own place with a wood stove.

 

[ShenKen]

I will add this but of info yet: the house will be pretty well insulated, with spray foam in the walls and rafters.

 

[begreen]

The main concern will be negative pressure in the basement. It would help to get outside air to the stove. Is this a daylight basement? Will the basement be insulated? Will there be an HRV or ERV system installed?

Most modern stoves with a few exceptions work on a 6" flue. Do you know what stove will go in? It sounds like the total flue system height will be closer to at least 30'. Draft strength may be an issue, but too strong, not too weak.

There is no reason to insulate the chase that encloses the chimney pipe as it passes through the floors. Some people add a grille, top and bottom of the chase to permit warm air from the chase to convect into the room. There will need to be a firestop at each floor.

 

[EbS-P]

how much wood do you want to burn a year? ie weekend, holidays, polar vortex or 24/7?

What is the layout of the basement? How will heat get upstairs?

As an owner of a house with 1200sq ft walk out basement and 2000 sq ft upstairs with a stove in each. The basement would be very hot if we wanted to heat the whole house from there.

Put the stove where YOU the person wanting and running the stove will spend most of your time. I’d compromise and get two value brand stoves (one for each level) over one big expensive basement stove.

 

[ShenKen]

Thanks for your response, begreen. In answer to your questions:

One end of the basement is daylight/walkout. I don't see a way to hide an outside air duct by going out the end at floor level. But if I went up, it could run behind a brick accent wall that we plan to have behind the stove. I believe going up with outside air supply can have its challenges though.

Basement is insulated. Precast concrete walls with foam insulation rated at R-22.

Probably no HRV or ERV. A dampered fresh air duct will connect to the central ductwork to provide passive makeup air for the kitchen exhaust. Under consideration is a small blower that would provide a constant low flow of air coming into the house.

I currently own an Englander 30-NC (bought new in 2016 and never used). It is rated for 2400 sq ft, but might it exceed that in a well-insulated home? It has a 6" flue collar. We plan to try this stove but I worry about potentially needing a larger stove with a larger flue size. On the other hand, we might be content to have it as supplemental heat along with the heat pump.

We do not plan to insulate the chase against inside walls, just outside.

 

[begreen]

Yes, I was thinking furnace when reading this.

 

[ShenKen]

how much wood do you want to burn a year? ie weekend, holidays, polar vortex or 24/7?

What is the layout of the basement? How will heat get upstairs?
...

I like to think we would heat entirely with wood but in reality I don't know if my time or energy will actually hold up to that.

I'll attach a floor plan of the basement. Warm air can radiate up through the floors (uninsulated) and also possibly up the U-shaped stairway(s).

Having two stoves is a new thought - I like it! But then we'd be looking at two chimneys, and I'd have to think over whether we have a good spot on the main floor for a stove...

 

[bholler]

Thanks for your response, begreen. In answer to your questions:

One end of the basement is daylight/walkout. I don't see a way to hide an outside air duct by going out the end at floor level. But if I went up, it could run behind a brick accent wall that we plan to have behind the stove. I believe going up with outside air supply can have its challenges though.

Basement is insulated. Precast concrete walls with foam insulation rated at R-22.

Probably no HRV or ERV. A dampered fresh air duct will connect to the central ductwork to provide passive makeup air for the kitchen exhaust. Under consideration is a small blower that would provide a constant low flow of air coming into the house.

I currently own an Englander 30-NC (bought new in 2016 and never used). It is rated for 2400 sq ft, but might it exceed that in a well-insulated home? It has a 6" flue collar. We plan to try this stove but I worry about potentially needing a larger stove with a larger flue size. On the other hand, we might be content to have it as supplemental heat along with the heat pump.

We do not plan to insulate the chase against inside walls, just outside.

You cannot run a fresh air intake above the stove

 

[EbS-P]

Having two stoves is a new thought - I like it! But then we'd be looking at two chimneys, and I'd have to think over whether we have a good spot on the main floor for a stove...

It’s nice till it’s not. Like trying to light/reload both with 15 minutes of each other.

Consider a whole home dehumidifier with fresh air intake. I may depend on what part of VA you are in. We are coastal NC love the whole house dehumidifier.

 

[ShenKen]

Say I'd go ahead and install a 8" chimney and later desire a smaller one. Would there be any feasible way to reduce it without completely replacing it? Theoretically it seems it would be safe to just slide a 6" stovepipe down inside the 8" but I'm not sure how it would be supported.

I feel like you'll be thinking I'm crazy for asking such a question, but you don't get answers if you don't ask!

Thanks for all the replies so far!

 

[kborndale]

The vast majority of modern stoves run on 6" flue so your probably best off running that. With a 25 ft chimney your problem will be the draft is too strong, not too weak.

 

[EbS-P]

Say I'd go ahead and install a 8" chimney and later desire a smaller one. Would there be any feasible way to reduce it without completely replacing it? Theoretically it seems it would be safe to just slide a 6" stovepipe down inside the 8" but I'm not sure how it would be supported.

I feel like you'll be thinking I'm crazy for asking such a question, but you don't get answers if you don't ask!

Thanks for all the replies so far!

Have you looked at the price difference between 6” and 8” double wall and class A?

 

[brenndatomu]

Sounds to me like a whole house wood furnace would be a good solution here...