Interpreting minimum chimney length

[mol1jb]

Hey all,

So some manuals specify that minimum chimney length is X length measured from the bottom of the stove to the top of the chimney. Others don't specify but to say minimum chimney length is X. Is it general knowledge that you measure the minimum length from the bottom of the stove to the top of the chimney or does it differ with manufacturer?

Thanks,

 

[burnbabyburn139]

My usual understanding is this applies to the total system height, so including the height of the stove. What kind of stove do you have?

 

[mol1jb]

I dont have one currently. I am just making sure that whatever one I do end up with that I can make it work well.

 

[edyit]

my own personal interpretation was height of exterior chimney. this is only because i have 2 90 degree bends in it. i come 2 feet up from the stove then a 90 into a wall kit then another 90. from there it is 15 feet. if it was all straight up i would have just counted it from the top of the stove.

 

[mol1jb]

my own personal interpretation was height of exterior chimney. this is only because i have 2 90 degree bends in it. i come 2 feet up from the stove then a 90 into a wall kit then another 90. from there it is 15 feet. if it was all straight up i would have just counted it from the top of the stove.

Interesting. Perhaps this is not a bad way to look at it since there is some restriction with the elbows. My setup will be similar with a through wall then straight up

 

[Highbeam]

A stove isn't a chimney. So unless they specify to include the stove height, chimney height is chimney height from where the chimney attaches to the stove to the very top. Not length, but height. Each bend in the chimney subtracts from the effective chimney height since it adds restriction.

 

[begreen]

Stoves are testing on a 15' straight flue system. For best performance aim for that minimum unless the manual offers a shorter alternative. The measurement is for a straight up chimney. As a general rule one needs to deduct 2ft of height for each 90º turn in the smoke path. Horizontal runs also slow down smoke and need to be kept at a minimum, preferably pitched upward toward the chimney at least 1/4" per foot. Altitude will also affect the height requirement.

 

[mol1jb]

Stoves are testing on a 15' straight flue system. For best performance aim for that minimum unless the manual offers a shorter alternative. The measurement is for a straight up chimney. As a general rule one needs to deduct 2ft of height for each 90º turn in the smoke path. Horizontal runs also slow down smoke and need to be kept at a minimum, preferably pitched upward toward the chimney at least 1/4" per foot. Altitude will also affect the height requirement.

So basically if I have an elbow to a T then straight up I should try to hit closer to 19'?

 

[begreen]

Yes, though it depends on the stove brand, stove location, chimney location and terrain too. If 20ft is not going to tower over the house then that should work well. Remember the 10-3 -2 rule when planning.

 

[mol1jb]

The house is a ranch with a 12/5 pitch roof. 8' ceilings on main level. So if I am thinking this out right, from the stove (assuming height of 3ft to make it simple) 5ft to ceiling and 5ft to the peak of the roof. I am looking at 2 used stoves right now. PE Super 27 and Napoleon 1100 Pedestal.

 

[mol1jb]

The PE Manual states 15' minimum chimney from the floor of the stove. The Napoleon manual doesn't specify.

 

[begreen]

Yes, that's the tested height. I've seen several installations with a bit less that still draft ok. A friend has the Summit working on 12' of chimney with a pair turns. It should draft terribly but it works ok. PE stoves have a larger, less circuitous secondary air manifold. Look back here on Napoleon complaints and I think you'll find that most are either wet wood or too little chimney.