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Post by wiscojames on Oct 19, 2014 17:29:12 GMT -8
I have an old brick chimney that I will be having tuck pointed soon, and outfitted with a rain/critter cap. From the cleanout in the basement, It seems to draw very well. It sits in the center of the 2 story house and the top is 3 or 4 feet above the roof. It has a thimble as well in the basement. Even though not ideal, the basement is really the only place I can manage a RMH without redesigning my house.
My question is: do I just vent straight into the brick chimney, assuming that it is without any major leaks anywhere in the chimney? Are there other reasons not to do this? It seems that it would work and would certainly be the easier way.
Alternately, I was thinking of lining it. If it will only be used for a RMH (and not a wood burning stove), I could get away with using HVAC ducting, right? The temperatures should be low enough, right? With this option, I could also insulate around it with perlite, though it is effectively inside the heated house. Besides, I'm not sure I could afford to line it with chimney pipe proper, much less double walled.
Thanks in advance, and sorry if this has been covered elsewhere.
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Post by pinhead on Oct 20, 2014 8:57:12 GMT -8
If the entirety of the chimney (except what is above the roofline) is inside the house, I wouldn't get it lined. A chimney at the center of the house would make an excellent bell heat exchanger. You would basically place the "roof" of the bell at the same height as the ceiling of the first floor (and the ceiling of the second bell, if desired, at the ceiling of the second floor).
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Post by wiscojames on Oct 20, 2014 9:05:21 GMT -8
Thanks for that insight - all I was hearing was crickets...
That sounds like a solution that involves some work inside the chimney. I think I understand the gist of what you are proposing, and I may be up to the task if it creates the ideal solution. (though it sounds like a heck of a lot of work) However, I was concerned mostly with the feasibility of using that bare brick unlined chimney to vent a RMH into. You think it's an OK idea, I gather?
The bell idea in designed to use the mass of the chimney as the 'battery', right? Warm up the bricks of the chimney for slow heat distribution thereafter?
thanks again!
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Post by matthewwalker on Oct 20, 2014 9:45:28 GMT -8
James, I have been quiet because you are asking a question that is really a question of assuming risk. I'll just say that if I were you, I would use it for sure, but it's hard to give someone else that advice. If you haven't already, do some reading up on chimney maintenance and new wood stove installs and get a good understanding of the hows and whys of liners and the like. I do think that RMHs alleviate a lot of the concerns that wood stove users have about old chimneys. Nonetheless, the risks are real and their concerns are valid. If you were asking this question on a wood stove forum the answer would be an unequivocal "no", so yeah, these types of questions will always bring crickets for the most part. The best advice would be to install a true liner, but.....
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Post by pinhead on Oct 20, 2014 9:51:33 GMT -8
Thanks for that insight - all I was hearing was crickets... That sounds like a solution that involves some work inside the chimney. I think I understand the gist of what you are proposing, and I may be up to the task if it creates the ideal solution. (though it sounds like a heck of a lot of work) It's what I'd try to do - there will definitely be some "engineering" involved. I am envisioning somehow suspending upper-level portions of the system from the top and building the lower level up from the bottom. The drawing is nothing more than a conceptual depiction and I actually have no idea what it would take to put it together. However, I was concerned mostly with the feasibility of using that bare brick unlined chimney to vent a RMH into. You think it's an OK idea, I gather? Yeah, I wouldn't worry about it - if it's sound enough to vent a fireplace, it's most definitely sound enough to vent a rocket stove. The mass of the chimney will have to be warmer than the outside air in order for draft to be established, though. I would definitely want to completely seal the chimney off so all of the air being drawn by the chimney is forced through the rocket stove - I wouldn't simply stick an exhaust pipe up into the chimney with a space around it. The bell idea in designed to use the mass of the chimney as the 'battery', right? Warm up the bricks of the chimney for slow heat distribution thereafter? Yes - the chimney, itself, is the thermal battery. No problem! EDIT: After reading Matthewwalker's reply: James, I have been quiet because you are asking a question that is really a question of assuming risk. I'll just say that if I were you, I would use it for sure, but it's hard to give someone else that advice. If you haven't already, do some reading up on chimney maintenance and new wood stove installs and get a good understanding of the hows and whys of liners and the like. I do think that RMHs alleviate a lot of the concerns that wood stove users have about old chimneys. Nonetheless, the risks are real and their concerns are valid. If you were asking this question on a wood stove forum the answer would be an unequivocal "no", so yeah, these types of questions will always bring crickets for the most part. The best advice would be to install a true liner, but..... I must add a caveat to my statement(s). the above design assumes the chimney is sound with no cracks and no obstructions. As Matt said, a cracked/unsound/old chimney can present various challenges in itself even when used in its "normal" configuration. All necessary steps must be followed in order to verify the structural stability of the chimney. With the "bell" configuration, there will be very slight pressures inside the chimney until the uppermost outlet is warmer than the outside air.
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Post by satamax on Oct 20, 2014 9:59:55 GMT -8
Wisco, read this whole thread. donkey32.proboards.com/thread/1274/rocket-heater-fireplace-designThen take pics of what you have, and take dimensions. Then, remember that if you have a little hearth, fireplace or even a hole. It's far better to have a rocket where you're living instead of in the basement. And this solution of having a bell frees you from most of the weight problems.
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Post by wiscojames on Oct 20, 2014 10:18:19 GMT -8
Thanks. You guys are great! I knew the cavalry would arrive sooner or later. And I guess that since it was only 16 hours later, it was really lightning fast!
Matt - I get what you are talking about regarding risk tolerance, etc Pinhead - you have me thinking about bells, and thanks for the reminder to keep the whole thing airtight. Satamax - I really want it in the living space, but it doesn't seem possible, given the layout of the house. I could replace the electric range with it, but I believe my wife would frown upon that solution. As I envision it, it would serve as supplemental heat and could be backup heat in an emergency. But in the next house...
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