IF I ADD 4 FEET TO MY CLASS A CHIMNEY DO I NEED TO SUPPORT IT - SEE PIC

[JotulOwner]

My setup has a Class A T- connection and a 90 degree stove pipe elbow. After taking a closer look at the impact this has on my draft, I learned (with the help of another Hearth.com member) that my overall chimney height probably is not quite enough. I always thought there was something wrong because, despite dry wood and a lot of attention to other details, I never seem to avoid some small amount of smoke rolling out of the stove when the door is opened (even slowly and even when the door is open for a period of time). I also never seem to see the stove temperatures expected under ideal conditions. My glass door also tends to get dirty easily and people tell me that Jotul stoves really need optimal draft conditions to avoid problems.

The photo shows my chimney which has an overall height from ground level (also just above sea level where I live) of 22 feet. If this was a straight pipe, that would be more than fine. However, when you figure in the loss of effective chimney height caused by the pipe turns and the 2.5 feet above ground level the stove pipe connects to my stove, I have about 11.5 (effective) chimney height which isn't enough for proper draft.

Anyway... my question is whether or not I need to add an exterior support to the pipe if I add a 4 ft section to what I have. My chimney chase (enclosure) extends above the roof line and the pipe presently extends about 2 feet beyond that. An additional section will be a total of 6 feet above the top of the chase. I am not sure where the highest support bracket is inside the chase, but it mounts to the side of the house somewhere within the chase. I imagine that the stainless cover on the chase acts as the highest support point. BTW, I can't effectively extend any supports to the roof because the pitch is ahallow and it would really be a long run to the roof.

Any opinions or advice would be appreciated.

Thanks
Art

 

[jacobk]

I'm not sure if different brands of pipe require different support. I just installed some class A from Selkirk and in the manual it says anything over 5 feet requires a roof guy kit.

 

[begreen]

That is correct. Every 5 ft over the roof penetration should be supported. However, an additional 4 ft is going to look awkward. Is there anything that can be done to soften the interior 90 deg turn (s). How is the stove connected to the tee? How many 90's?

 

[JotulOwner]

That is correct. Every 5 ft over the roof penetration should be supported. However, an additional 4 ft is going to look awkward. Is there anything that can be done to soften the interior 90 deg turn (s). How is the stove connected to the tee? How many 90's?

Three feet of double wall stove pipe above the stove into one 90 degree elbow then 1.5 feet horizontal into the Tee (another 90 degrees) all adding up to the need for an additional 8 feet over a typical minimum height chimney for proper draft. I could add a 3 ft section of class A (total height above the chase 5 ft) to eliminate the need for a brace or I could have the chase extended which won't be cheap. I could also try to reduce the angle of the stove pipe, but that isn't the easiest solution either.

 

[begreen]

I was thinking using 45's also, but see what you mean. In 6", if the 45 came right off of the thimble, then the 18" piece, then a second 45, you would need about a 10" length to connect to the stove.

Have you put a level on the 18" section to see how much pitch there is heading toward the chimney? It should be at least 3/8-1/2" over the 18" length.

Is the stove rear or top vented? What is the class A sized pipe - 6 or 8"?

 

[JotulOwner]

I was thinking using 45's also, but see what you mean. In 6", if the 45 came right off of the thimble, then the 18" piece, then a second 45, you would need about a 10" length to connect to the stove.

Have you put a level on the 18" section to see how much pitch there is heading toward the chimney? It should be at least 3/8-1/2" over the 18" length.

Is the stove rear or top vented? What is the class A sized pipe - 6 or 8"?

The horizontal pipe looks like it has a slight pitch , but not very much. The stove is top vented. 6 inch ID pipe.

 

[woodmiser]

Can you post pics of the stove setup?

 

[Backwoods Savage]

Code usually calls for 1/4" rise per foot of horizontal as a minimum.

On the chimney height and smoke problem I still wonder if perhaps it is more of a problem with wood than with the chimney. I say that because our chimney is also too short according to theory but we get along just fine. We also have a horizontal going through the wall with 1/2" rise per foot of horizontal. We also burn very dry wood.

 

[JotulOwner]

The wood I use is very dry. In fact, on a windy day, using wood from the same pile, I find a huge difference in draft.

 

[begreen]

If the stove pipe is indeed pitched upward toward the chimney, it sounds like you have done things by the book. I would expect draft to be adequate, not great, but sufficient when temps get in the 30s or below. Two areas to check would be sealing the flue collar if there is any leakage there and checking the tee cap for a tight fit.

In a prior thread you mentioned that you used an 8" brush to clean the chimney. Is this 8" class A or was that just a typo?

 

[JotulOwner]

If the stove pipe is indeed pitched upward toward the chimney, it sounds like you have done things by the book. I would expect draft to be adequate, not great, but sufficient when temps get in the 30s or below. Two areas to check would be sealing the flue collar if there is any leakage there and checking the tee cap for a tight fit.

In a prior thread you mentioned that you used an 8" brush to clean the chimney. Is this 8" class A or was that just a typo?

Good observation. The brush I now use is indeed 8" and the pipe is only 6". I know what everyone thinks when they hear that, but I find that a larger very soft flexible bristle brush works much better than a rigid one. I am not scraping thick caked-on materal (just light dusty soot) and I find this works much better because there is more surface contact.

Thanks for the pointers regarding pitch and leakage. I do use stove cement at some points to decrease leakage. Like you said, my draft is adequate under most conditions. I will see what minor changes will improve it, but otherwise, I will probably keep things as they are until I need to make larger repairs or upgrades.

 

[begreen]

Sounds like you have done stuff pretty much by the book. Check the small details to see if they need improvement, but it could be that cold weather is the best solution for increasing draft with no modifications. Have you tried cracking open a nearby window when the stove is starting to see if that makes any difference?