I'm a bit confused on RMH exhaust. In a typical wood burning stove exhaust is vertical because the fire is hot and wants to rise. With RMH I'm under the impression that all the rise happens in the heat riser and this pushes the "cold" air in whatever direction, and must fight gravity possibly? So, aesthetics aside, should I keep the system horizontal and vent sideways or plug into the chimney and expect it to climb 20 or so feet more efficiently? Some explanation would be awesome also.
An RMH will have cooler exhaust than a standard woodstove, but it should still be 100 to 200 degrees, and will create helpful draft in a vertical chimney. Also, the "horizontal exit" idea only works if you have a totally constant prevailing wind, which only happens in a few places. Most of the world needs the flexibility of a vertical chimney with its top at least a few feet above the roof, to draw without backdrafting in any wind direction.
What about 90's in the exhaust to get to the exterior- how does that effect the flow? I have a 4" system and am planning to use 4" stove pipe. I can either elevate my stove to the height of the window I will be mounting it next to (not my favorite idea) or throw two 90's between the stove and wall thimble with a third outside the thimble.
So I'm still a bit confused on whether to vent horizontal or vertically through chinney. My friend is telling me it won't come out hot enough to make it up the chimney and it might sink back down. He recommends running along the wall and punching out the wall near the window to keep all possible leaks contained. If venting out the chimney should I plug into the pipe sticking out and close the flue below it or just have an elbow facing up at fireplace level and open the flue? Thanks (:
What size is the existing chimney flue? And how tall? What condition is it in? If it is lots larger than your RMH system size, or if it is in poor condition, you may want to put in a liner (I have heard of stainless ducting used for this). Otherwise, as long as the chimney is at least partially built into the house, you would be better off using it. A cold plug on starting is an issue in some circumstances. How cold are your winters?
Going straight out the wall will not help you; you would then have to run a new metal chimney all the way up above the roof, and it would get even colder than the masonry chimney. A terminal at room level will only work if you have 100% reliable prevailing winds and your exit is on the downwind side. There are only a few places in the world where that is true.
How thick is the masonry on the exterior side of the fireplace? Is there an air gap or any insulation? What does the outside look like? (Is it beautiful or visually prominent?) If it is not visually important outside, you could cover it with some insulation and a new shell. This would let you use the fireplace mass as part of your system, which could save you some space in the room.
I'm not sure if I understand your questions. The chimney is a foot and a half by just over 4 feet wide. Probably 20 feet tall. It seems structurally intact. I live in Detroit so it gets to be as low as -40 sometimes? The chimney is pretty built into the structure. I don't understand your last paragraph. It comes out maybe 1.5 feet to 2 feet outside. I think the whole system is straight brick but I couldn't say for sure. What do you mean by using the fireplace as part of the mass? If I exit outside can't I just put a wind cap around it? Is there a chance that venting into the chimney it might not be able to rise out the top? I just don't want it to sink back down and kill me. Having kickback out the feed tube is one thing, having it not make it out the chimney is another. It would be better functionally if I can vent out the wall because I could make a longer bench. Regardless aesthetics are of no concern. Thanks!
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
if you want to be sour you on the safest side from the first time, put a new 6" duct into the old big chimney. the duct should go vertically until the upper end of the old chimney.
if you want to try to save money, you can try venting to the old chimney first.
don't listen to the friend.