Stove / Chimney plans - illustrated

[Richard Poor]

Thought I'd appeal to the collected wisdom here on our plans for the chimneys / wood heating which we're installing in a house we're reconstructing. The house is two full floors of 1600 sq. ft. each (40 x 40' square), with a full basement and a 300 sq.ft. cupola at top. (No, we didn't want a house this large, but it came with the farm we DID want. )

We are designing it so that the first floor will serve as the primary space for the two of us to live, with the second floor being used for guest bedrooms, office/work/hobby etc. We are planning on using the PE Summit to heat the first floor for the immediate future. We are building two separate masonry chimneys of 16x16 concrete block, one for the Summit and one for possible future use with a wood furnace in the basement. The house is currently ducted and we thought we could use a wood furnace for when the house is fully filed with friends and family. We are starting on the block work this week, with one stainless steel liner to be put in for the first floor. Both chimneys will be brought into the insulated building envelope during construction, but will still remain on an outer wall.

I've attached a fairly detailed drawing that shows placement and primary dimensions for the chimneys, which sit on a bump-out in the basement floor. In addition to the required clearances to combustibles, I believe everything as designed should meet or exceed code. We do have some things up in air at this point a) best height for thimbles b) how close should we place the masonry blocks to each other c) clean out options for the first floor stove and d) hearth design.

Any thoughts or suggestions on this approach?

 

[Todd]

Looks like a great plan. A couple suggestions since the flues will be side by side I would extend the main floor flue a bit taller than the basement flue to keep it from sucking smoke down into the basement (flue reversal). May also be a good idea to pipe in outside combustion air to both stoves.

 

[Richard Poor]

Looks like a great plan. A couple suggestions since the flues will be side by side I would extend the main floor flue a bit taller than the basement flue to keep it from sucking smoke down into the basement (flue reversal). May also be a good idea to pipe in outside combustion air to both stoves.

Thanks, Todd. I was wondering about the need for different heights, but could find no definitive answer on it. Though the second block chimney will remain empty/un-used for now, we'd like to build it correctly for later installs.

Where do I find what a recommend height difference between the two might be? I would be looking at increments of 8" block. I do have some concern about making it too tall to clean from the roof. We're also trying to decide whether a 2" - 4" gap between the two chimneys is helpful or doesn't make any difference. We'll probably tie them together at the top somehow, either for additional support or for appearance.

While I'm at it, what is the best way to determine proper/good thimble height? We know it needs to be 20-24" below the finished ceiling, and higher than the stove, but is there any meaningful difference say between 5' or 6'?

 

[begreen]

1-2 ft. difference is good. I would go for 6' for the thimble height. That will give it more vertical rise before going horizontal, yet stay comfortably away from an 8 ft ceiling. I see no reason for not placing the two chimneys touching each other. What is the reason for separating them? The final chimney height will be determine by code. It must be at least 3 ft higher than the roof exit and 2 ft higher than the nearest roof line.

 

[Richard Poor]

I see no reason for not placing the two chimneys touching each other. What is the reason for separating them? The final chimney height will be determine by code. It must be at least 3 ft higher than the roof exit and 2 ft higher than the nearest roof line.

View attachment 114653

We're in the position of having to get the chimneys done first (for heating), but don't know what final finishes will be for the exterior - stone, brick, whatever, etc. - so there's a possibility of needing a gap to accommodate a good layup. Talking it over with the mason this week. The other one is that I when I build, I tend to think in terms of "What happens if I have to replace this sometime in the future?" It's easier taking down something if you have a touch of room to do so.

Currently, we're planning for a chimney that's 5'-9"± above the roof exit and 2' above the roof line at a 10' horizontal. Wondering how the cupola (13'x21') and the massive amount of clear roof (62'x62') will affect air flow around the chimneys. Thinking that wind guards on the caps might be a good thing. Guess we'll find out shortly.

I still feel like I don't have a good solution for the cleanout on the SS liner for the first floor. I'd prefer to have a cleanout door below the T somewhere, rather than having to pull the stove pipe to clean it out, but it's proving problematic. We're looking at a fairly long snout body on the connector - possibly 14"-20" depending on the finished hearth - and I don't know how much of a hassle that would be. Considered doing a short section of rigid pipe below the T connected to another short body T at the end extending to a cleanout door at the base of the first floor stove or a touch higher.

 

[brenndatomu]

I'll tell ya what I did on my chimney when I put the liner in it last year and wanted to retain the ability of using the cleanout door. I talked to the guys at Chimney liner depot about it, they said it would be fine to put a "leg" on the bottom of the tee. They had to make a couple minor alterations to my tee and bottom cap to make this all work out which they did for no extra charge.
So I have flex liner down to the tee, then a 4-5' section of flex on the bottom of the tee. I kept the bottom of the leg up off the floor 4-5" so I can get the cap off and slide a pan under for cleaning. When I'm done, the cap goes back on and a couple bricks go under to hold it on and to "help" support everything. Works out pretty well.

 

[begreen]

I'm not understanding why the extra step of the masonry just to hold a liner. Why not just put up two class A chimneys and chase them?

 

[Richard Poor]

I'm not understanding why the extra step of the masonry just to hold a liner. Why not just put up two class A chimneys and chase them?

Tradition and unique house style. My original intent was to go with a clay flue, but it seems that SS is the overwhelming choice these days.

 

[begreen]

Screw tradition. Are you going to be looking at the cement block flues? A class A system in a chase is the way to go here imho.

 

[Richard Poor]

Screw tradition. Are you going to be looking at the cement block flues? A class A system in a chase is the way to go here imho.

I can appreciate that perspective in some areas of my life, but not all. I own a couple of 100-year-old buildings in our downtown and have spent years doing historic renovations on them, including some traditional methods and materials. Cement block with insulated SS liners is what's planned.

 

[begreen]

Heck, you better go brick then. It has been around much longer than cement block chimney and is more "traditional".

 

[Richard Poor]

Heck, you better go brick then. It has been around much longer than cement block chimney and is more "traditional".

I'll take that under consideration. I had originally thought we'd just go with rough field stone daubed with pig-crete for mortar. The block will be surfaced later, likely with stone or brick.