chimney construction for coal?

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NJJoe
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Post By: NJJoe » Mon. Oct. 30, 2017 9:36 am

I'm recently married and my wife and I are looking to settle into our marital home where we can put down some roots and really start customizing the place to our exact liking. We currently live in a 2 family house; living with an upstairs tenant is getting old. She is onboard with coal, loves the looks of old stoves and knows how comfortable and warm coal heat is. In our new home, my goal is a stoker boiler to do the whole house but I'll accept a room stove or even a kitchen range. The goal is to purchase a home that is either coal ready with respect to the chimney or construct a chimney with that purpose in mind.

Existing chimney. Can you guys give me some pointers of what to look for in an existing chimney or what to avoid? Something that can be ascertained with a mirror stuck in the cleanout door? Or, the house may need work/renovation and I'm not beyond contracting a mason to construct a chimney with coal burning in mind. I suspect that not many masons have the know how to build a chimney with coal in mind. One of those dying arts/lost knowledge type of deals.

Size or internal diameter? Looking for a rule of thumb more or less. I'd estimate the house would be 2000 sq ft, maybe even up to 3k. Does the chimney care what dumps into it? (stoker boiler, stove or range. or is coal the same no matter how it is burned?) Do chimneys come in a round internal flue sections? I've pretty much only see rectangular/square terracotta sections. I also have seen a formula that dictates the height of the chimney and must be x amount of feet from the nearest tallest structure in order to draft properly.

Inside material selection? What I know is to avoid a steel liner which corrodes over time with coal burning. Any consideration given to fly ash accumulation and what design to build to avoid or mitigate this? I'd imagine a straight up chimney that avoids any bends or corners. Is terracotta a good choice? What about using firebrick? Are chimneys "insulated" in order to retain heat and draft better? Id imagine outside chimneys will draft worse than chimneys surrounded by the structure.

Chimney fires? I will primarily burn coal but we like wood too and would burn firewood during the shoulder months. Will built up creosote become a danger if I switch to coal when the season calls for it?

Chimney cap or other decorative type of topper recommended? My current chimney needed to be cleaned out at the base. When I bought this house, I removed bird nests, pine needles, dead animals from the bottom. When it rains heavily, the basement floor gets stained with black residue runoff that leaks from the cleanout door(oil burning chimney) so I think it would be helpful to keep the rain, critters and other debris with a cap or something similar.

Thanks in advance for suggestions.

-Joe

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lsayre
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Post By: lsayre » Mon. Oct. 30, 2017 11:02 am

You want a terracotta (tile) lined chimney. Accept no substitutes. Caps are OK. Ideally you want at least 15' of chimney above the flue entry. Legally only one appliance per chimney. Cross sectional area must equal or exceed the same for your coal stoves flue outlet.

Stainless steel is designed for caustic wood ash, and coal is acidic, so it eats stainless.

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Lightning
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Post By: Lightning » Mon. Oct. 30, 2017 4:15 pm

An Interior chimney is preferred over an exterior chimney for burning coal. Coal burning is much more efficient than wood in that more of the heat is radiated to the home, leaving less heated air mass for the chimney to create draft with.

I have an exterior chimney with tile liner. It works great a majority of the time. During warm weather when the furnace is only idling the draft can fail unless I keep a lot of secondary air over the fire. This happens because during nighttime the chimney cools and then the ambient daytime temperature becomes warmer than the chimney.

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Post By: Rob R. » Mon. Oct. 30, 2017 4:41 pm

Interior over exterior.
Masonry over stainless.
Insulated over non-insulated.

NJJoe
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Post By: NJJoe » Tue. Oct. 31, 2017 8:51 am

What might you insulate a chimney with? I have a ton of roxul batts (stone wool) leftover from past renovations. Its not flammable and has good r value. Would that be a good choice?

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freetown fred
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Post By: freetown fred » Tue. Oct. 31, 2017 10:29 am

It will be an excellent functional/ monetary choice N! :)

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Post By: Rob R. » Wed. Nov. 01, 2017 6:01 am

NJJoe wrote:
Tue. Oct. 31, 2017 8:51 am
What might you insulate a chimney with? I have a ton of roxul batts (stone wool) leftover from past renovations. Its not flammable and has good r value. Would that be a good choice?
Vermiculite.

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coalkirk
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Post By: coalkirk » Thu. Nov. 02, 2017 7:02 am

Vermiculite would work well but be aware that almost all vermiculite contains asbestos. Take appropriate precautions.

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Post By: k-2 » Thu. Nov. 02, 2017 9:20 am

I just built a masonry clay flue lined chimney 35Ft high, I was thinking about SS insulated Triple wall but the materials alone were prohibitively expensive and it would not have been good for coal. The masonry chimney should last the life of the home and will handle just about anything thrown at it. Labor intensive but the materials were reasonable $500 to $600. Check around,most places want almost $10 for chimney block ,i paid $4.95 @ for quality block. Just that alone would have added over $200 to the materials bill.
Last edited by k-2 on Thu. Nov. 02, 2017 9:45 am, edited 2 times in total.

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Post By: k-2 » Thu. Nov. 02, 2017 9:22 am

Rob R. wrote:
Mon. Oct. 30, 2017 4:41 pm
Interior over exterior.
Masonry over stainless.
Insulated over non-insulated.
Good advice!

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k-2
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Post By: k-2 » Thu. Nov. 02, 2017 9:25 am

k-2 wrote:
Thu. Nov. 02, 2017 9:20 am
Draft ok on startup .pulls like crazy once warmed up.
Last edited by k-2 on Thu. Nov. 02, 2017 9:38 am, edited 1 time in total.

k-2
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Post By: k-2 » Thu. Nov. 02, 2017 9:25 am

k-2 wrote:
Thu. Nov. 02, 2017 9:25 am
If burning wood, should be checked for creosote buildup periodically.
Last edited by k-2 on Thu. Nov. 02, 2017 9:40 am, edited 2 times in total.

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Post By: franco b » Thu. Nov. 02, 2017 9:27 am

I would add that round flue tile is to be preferred.

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Post By: k-2 » Thu. Nov. 02, 2017 9:34 am

franco b wrote:
Thu. Nov. 02, 2017 9:27 am
I would add that round flue tile is to be preferred.
Iv never seen that in this area. Standard around here is a square 8 in clay liner with roughly a 7In. inside Dia. The thimble that the stove connects to is always round.

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