Chimney height too short?

[Komatsu350]

I am getting ready to install my new buck 74, so today i was measuring the chimney height to order a new liner.
From top of flue down to finish floor of chimney is 16'6", the stove stands 20" tall which makes only a 14'8" flue. The buck 74 takes a 6" liner. The liner will be insulated along with a block off plate and roxul top and bottom. Does the flue seem to short? Im worried about drafting problems? If not would you order the 15' kit or would you bump up to the 20' to be safe????

 

[Komatsu350]

** it is also an exterior masonry chimney is sw ohio.

 

[stovelark]

Measure 4 times, buy once. Most companies list a minimum chimney- 11 to 14 feet. you'll have to try it and see. Give it good seasoned dry wood. You'll probably find it works great. Insulating the liner and sealing it properly will only enhance the operation.

 

[begreen]

I think most companies list the minimum chimney height for their EPA stoves as the EPA tested height of 15', but there are notable exceptions. PE and Enviro stoves work ok with shorter chimneys. My theory is this is because the airflow in secondary manifold path is less restricted. Not sure about the Buck 74, but agree that it's worth a try to see how it performs with the 14'8". It may work fine.

 

[Ella Rollins]

Chimney which is too short may cause serious fire hazard like setting fire in the roof and too short heating flue can cause dangerous CO poisoning hazards. Normally the top of the chimney flue must be at least 2 ft above that point.

 

[mellow]

I would order the 20ft insulated kit, I always find it best to have more on hand "just in case" than not enough. I ordered 5 feet extra on mine and have ended up using it through the years.

Buck says the 74 will work on 12-15ft minimum height chimneys, so you are within "specs". Specs is usually for middle of the winter when your draft will be best, during shoulder season you will probably see some smoke spillage when you open the door.

Buy it, install it, see how it runs this winter, if it gives you draft issues you could install a base plate and switch to class a for extending above the chimney a couple feet.

 

[kennyp2339]

You can always add an anchor kit to the top of the chimney and then add an additional 3ft of class a pipe with a cap to get extra height.

 

[Highbeam]

Chimney which is too short may cause serious fire hazard like setting fire in the roof and too short heating flue can cause dangerous CO poisoning hazards. Normally the top of the chimney flue must be at least 2 ft above that point.

I think you are mistaken about what the OP is describing. The overall chimney is 17 feet tall and he is worried that it is not long enough to draft properly with his stove. Not the same as saying that the portion of chimney above the roof is shorter than code. We often hear about the 10/2/3 rule when designing the portion of the chimney above the roofline. That is the top of the chimney, not the top of the cap, must be at an elevation 2' above any roof within 10' and also no less than 3' above the roofline.

The buck is a non-cat and will work great on 14-15' of vertical liner. Even better if that liner is insulated and tightly sealed to the stove and the cap. Leaks in the flue cause a loss of draft.

If you only need 14'-8" then you can do this with the 15' kit but you'd better be sure that you've accounted for non-vertical wiggles and even the flue connection that are non-vertical can burn up overall length. It may be possible that the liner vendor actually sends you 16+ feet with a 15' kit. Might as well ask. I hate buying extra and wasting it.

 

[Ashful]

Insulated 6" liner with block offs above and below... you're giving it the best possible shot at working, and I'm sure it will work well in colder weather. The usual penalty for a chimney of less than optimum length is reduced draft on warmer days, which may be something with which you just choose to live. I have two chimneys, one very tall, and another only a foot longer than yours. I choose to just not load stove on the shorter chimney in weather much above 40F, whereas I routinely run the stove on the taller chimney on days peaking above 60F. Luckily, this agrees well with the dynamics of my house, so it's basically no penalty.


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