in another thred Don said something about chimney height increasing for each use of an elbow. does this include a 90 elbow used on a rear exit? I am installing a jotul 602 and have been trying to decide between a top and rear exit. total height of stove pipe and class a will be around 13 ft, and with the rear exit I would use doublewall. is this sufficent? don, can you explain again the requirements associated with elbows/chimney height? thanks.
elbows and chimney height
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Its just a rule of thumb, every 90* elbow adds 5' of chimney, the first 90* elbow is a free bee and doesnt count, so the one elbow would not count on the 602.
- Nov 21, 2005
- 827
I believe the 13 ft is too short isn't it? I don't know the exact length, but doesn't code say it has to be something around 16' tall at least?
Having a chimney that's too short creates poor draft. I'm all too familiar with the issues of poor draft. Things like, difficulty in getting a fire started. You light a fire, it looks to be going good, you close the door, and out it goes. Rinse, and repeat several times. Or, you go to put another load in, and open the door and whoosh smoke starts pouring into the area until you're done. It also prevents you from being able to use your unit when it's warmer out. You may not know this, but the colder it is outside the easier things are. A unit with good draft, might be fine to use when it's as warm as 50-55F. Not so with a unit with poor draft, they may prove to be finicky or very difficult when it's any warmer than 45F. Hope others can clarify.
Having a chimney that's too short creates poor draft. I'm all too familiar with the issues of poor draft. Things like, difficulty in getting a fire started. You light a fire, it looks to be going good, you close the door, and out it goes. Rinse, and repeat several times. Or, you go to put another load in, and open the door and whoosh smoke starts pouring into the area until you're done. It also prevents you from being able to use your unit when it's warmer out. You may not know this, but the colder it is outside the easier things are. A unit with good draft, might be fine to use when it's as warm as 50-55F. Not so with a unit with poor draft, they may prove to be finicky or very difficult when it's any warmer than 45F. Hope others can clarify.
The only code for hight is the 10/2/3 rule, it doesnt address over all hight. In a lot of parts of the country 13' is close to the minimum. It would never work up where i live, but it should work any place that is close to sea level. Your house realy determins the hight of the chimney, some places 13' will work fine, some places it wont. Lots of factors, the biggest being negative pressure, have the biggest effect on draft. If i had a choice, i would add a little more, what is the minumum the 602 recommends? I will have to look it up.
The manual doesnt give the minimum, worse case scenario is that you add more pipe if performance isnt what it should be. Of course the 10/2/3 rule has to be satisfied no matter what.
The manual doesnt give the minimum, worse case scenario is that you add more pipe if performance isnt what it should be. Of course the 10/2/3 rule has to be satisfied no matter what.
- May 1, 2006
- 118
MountainStoveGuy said:
Does that mean using the rear exit will yield as much draft as the top exit?
My system isn't much more than 13' - but it's a one-storey building (with small crawl in attic). 7 1/2 feet of chimney, draft is fine.
How about a side exit? I'm using a side exit now - it had been rear exit. Any difference? Does that count as another 90* more than rear exit? I can't really compare because I changed too many other variables at the same time as I switched to side exit - chimney diameter, stovepipe configuration, started using the smoke shelf/baffle.
top exit vs rear exit is a highly debatable subject. you dont get dinged with the five foot rule with the first 90* elbow, i cant realy comment on the combustion efficiency with top vs rear, but draft should be about the same.
MountainStoveGuy said:
That's good to know. I was counting my rear exit as one of my 3 90's. Draft is great anyway.
All elbows count for 90 degree bends but the 90 tee for some reason is not factored in to increase chimney height
I know they both turn 90 degrees or the use of one tee is permitted There is also a 180 maxx degree bend rule in the run
I got to run now I will add more later if needed
I know they both turn 90 degrees or the use of one tee is permitted There is also a 180 maxx degree bend rule in the run
I got to run now I will add more later if needed
thats because you always use a T and not a 90. A T and a 90* are the same thing. The same rule goes for up and outs, the first ninty going through the thimble, doenst count, but the T on the outside does. You dont add 10 feet extra pipe on a up and out, just 5'.
Since this was a long time pratice that i have used for the better part of the last 10 years, and i havent seen any documentation on it in a long time. I called hearthstone and jotul, and they both stated that the first 90 in the system does not figure in the equation, wither its a T in the back of the stove, or a 90 going out throuh a thimble.
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