hanee
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Posts: 23
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Post by hanee on Nov 18, 2020 4:12:02 GMT -8
I had planned on putting together a 4" system, but 4" insulated chimney is, as far as I can tell, only available from one specialty boutique with a 4 month back order (I am guessing imported from Europe). The only 4" pipe in the US readily avialble appears to be single wall (black) and pellet stove vents, usually galvanized with just an air gap.
5" is listed in the big manufacturers catalogues as an option at least, but doesn't seem to actually be carried by anyone.
6" is of course the commodity item. Readily available and generally cheaper.
So I may be forced into a 6" chimney as the one fixed part of my experiments (planning on experimenting with 4" DSRII and 4" Vortex).
I remember reading at some point on the forums a rule of thumb about chimney sized but am unable to locate it. I believe it was a post where Peter had said a 6" chimney would be ok (but the outer limit of ok) for a 4" system. But I may well be mistaken. Concerned because CSA is 225%.
If the CSA is too much, I'm curious whether there are any tweaks that could help it to work out, such as.
1. Running 4" pipe on the interior and then switching to 6" as I exit the roof and switch to insulated pipe (the chimney will likely have about 10' internally and 4' externally). 2. Adding some kind of restriction (already may need to jog over slightly with an elbow, more harm than good)? 3. Running 4" uninsulated inside the 6" possibly? (Tricky connection details/potential condensation management issues/safety?)
That said, I'm also fine increasing the system size but hopefully it's not that far off. I'd rather not build a 6" system when a 4" can suffice but maybe 4.5" (177%) or worst case 5 (123%) is okay.
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Post by josephcrawley on Nov 18, 2020 6:19:26 GMT -8
I built a 4 inch stove and had a similar dilemma about using 4 inch duct. Instead I used a 4 to 6 converter at the stove exit and it works just fine.
I say go for it. By the way the 4 inch firebox is very very small.
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Post by belgiangulch on Nov 18, 2020 7:49:07 GMT -8
I agree with Joseph; 6" adapter off your 4" pipe. However I suggest building a 6". Much easier to load , last longer , larger wood... win win The batchboxs do not have to be run full of wood. You can build any size fire your space needs. With a 4" firebox you are limiting yourself.
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hanee
New Member
Posts: 23
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Post by hanee on Nov 18, 2020 13:51:55 GMT -8
josephcrawley - I know Peter's multiplier allows "4-5.5 x base" for the depth of the firebox, out of curiosity did you chose to go for the deeper measure? I'm aware that the 4" is quite small (though, much, much larger than my original "tiny wood stove" options that I had originally planned when I started building our house). belgiangulch - The problem with the larger units is the larger foot print of the mass, but if I *knew* I was only ever going to fire with a half-load of wood I suppose I could run a larger foot print core (for the sake of the firebox) with a smaller, low ISA mass. 6", though, seems like quite a jump: both in terms of BTU and space used as compared to my needs. I know Peter's test-model DSRII is a 5" system and I got the impression he felt it to be more powerful than the standard 5" system. In any event, if a 6" chimney is fine, that solves the chimney problem AND allows me a broad range of trial-and-error on the heating system. Perhaps it would be wise to consider a 5" as something that worst case is a 25% too big or a 20% too small, vs something that risks being 50% off from ideal. But in either event, I can cross that bridge when I am in a position to be building the core, as right now I'm just framing the addition it's going in and ordering the chimney . Only about 2 years behind schedule!
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Post by josephcrawley on Nov 18, 2020 17:43:38 GMT -8
josephcrawley - I know Peter's multiplier allows "4-5.5 x base" for the depth of the firebox, out of curiosity did you chose to go for the deeper measure? I'm aware that the 4" is quite small (though, much, much larger than my original "tiny wood stove" options that I had originally planned when I started building our house). belgiangulch - The problem with the larger units is the larger foot print of the mass, but if I *knew* I was only ever going to fire with a half-load of wood I suppose I could run a larger foot print core (for the sake of the firebox) with a smaller, low ISA mass. 6", though, seems like quite a jump: both in terms of BTU and space used as compared to my needs. I know Peter's test-model DSRII is a 5" system and I got the impression he felt it to be more powerful than the standard 5" system. In any event, if a 6" chimney is fine, that solves the chimney problem AND allows me a broad range of trial-and-error on the heating system. Perhaps it would be wise to consider a 5" as something that worst case is a 25% too big or a 20% too small, vs something that risks being 50% off from ideal. But in either event, I can cross that bridge when I am in a position to be building the core, as right now I'm just framing the addition it's going in and ordering the chimney . Only about 2 years behind schedule! I went with the max depth as my wood was already cut to a cubit give or take in length.
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