Draft Question

[timfromohio]

Hi everyone

I posted earlier in the year (pics included) asking advice for stove install locations. My preferred location would result in a chimney that would not be higher than the apex of the roof of the house, though certainly high enough to meet safety requirements (2' higher than anything within 10', right?). My preferred stove is a Jotul F55, chimney height would be on the order of 16', 2/3 of the length external.

I'm now in the process of getting several estimates for the install. One potential installer is telling me that draft will be inadequate so long as the chimney height is not higher than the apex of the roof, even if a shorter length meets safety requirements.

Any opinions on this last statement?

Thanks!

 

[gzecc]

Could be right. Always variables with chimneys. Sometimes you don't know until its in.

 

[begreen]

Chimney draft is a bit more complex than than just location. It also depends on the prevailing winds, topography, adjacent structures, internal house pressure, outside temps, etc.. Your chimney may draft fine. If not, add a couple feet of pipe and a roof brace.

FWIW, our chimney is similar. It is a first floor chimney in a 2 story house, 20ft high, with about 7 ft sticking out of the roof and the cap is definitely a few feet lower than the roof peak. There is a roof brace at 5ft. The chimney is on the north slope of the roof with our prevailing winter winds from the southwest. Though not perfectly located this chimney drafts very well so far in all kinds of weather including very windy spells. With the T6 I can start a fire at 50 outside without smoke spillage.

 

[DougA]

Have to agree. Without seeing all the variables, it's hard to know. I changed my stove location 20' inside the same room with a similar chimney height. I went from so-so draft to probably too much draft. The old location was on the far side of the roof peak from the prevailing winds, the new one is right at the peak (1' off).

If you have problems, add the extra 3 or 4 ft. plus a brace. If the draft is fine without it, save the money. It's actually a good thing the installer is making the suggestion. Many refuse the believe the stove's problems are related to draft since an installer said so.

Don't forget that your stove's draft is also the sum of other variables. Dry wood & interior stove pipe (single vs. double wall) can make a big difference in how easily your stove burns.

 

[timfromohio]

Thanks for replies.

Begreen - any evidence of ash, etc. on the roof?

You know, I had a PE insert that ran 24/7 in the winter and a Napolean in another part of the house. Never thought too much about draft - both worked just fine. I was lucky.

 

[begreen]

No ash on roof that I've ever noted.

 

[timfromohio]

Thanks begreen. Meeting potential installer tomorrow afternoon and will provide an update afterwards.