Four inch flue

Will a pellet stove (4 inch flue) work efficiently if connected to an 8 inch flue, or will I need to run the 4 inch flue pipe up the 8 inch flue?

 

It's my (albeit limited) learning from this site that it is acceptable to go from a smaller flue pipe to a larger size pipe, but not to go smaller.

However, going from 4" to 8" may cause draft issues.

If you can run the 4" up the 8" stack, it may be the safest option.

$.02

 

Since an 8" pipe is 4 times the area that a 4" has (12.5 vs 50) I'm saying it won't draft well without going to the top with the 4"

 

I ran a 4" pipe into an existing 10" wood stove pipe (see pic). No problems at all.

 

Thanks for the input, this is what I was thinking would be the case.

 

I guess I should have asked if it was natural draft, or has a blower...I'm sure that makes a difference too...(maybe all pellet stoves have a draft blower?)

 

that being said, a central chimney (no sides exposed to the elements) will draft better than a chimney with 3 sides exposed to the elements, the idea being the exhaust gasses cool more before reaching the top of the chimney and slow down. So, a 4" exhaust adapted to a larger, intact flue will work better in a central chimney. Also do not forget that virtually all (with the exception of the Wiseway) modern pellet stoves use a fan to expel exhaust (combustion fan), so this system actually doesn't rely solely on natural draft to expel exhaust. Of course, the chimney should be checked for structural integrity first. If thats questionable, use a liner. If its an old brick or stone chimney without a good clay liner, use a liner anyways. And of course you all know not to use a liner smaller than the stove outlet.

 

The pellet stove being a FORCED draft the 4 to 8 connection is going to work just fine.

The only caveat will be the possible build up up ashes in the lower "ledge" where the transition occurs.

Depending on the chimney height this could be a paint to clean out.

 

I have absolutely no problems with that.
Using the same ~40 year old chimney that I have used with
Wood stove
Coal stove
Now pellet stove...

Dan

 

Never seemed to be an issue with mine. That said, I still ran the Lint Eater brush high enough so I knew it was at the "ledge" level, let it flop around for 5-10 seconds there, and that was it. Even if some ash built up on that ledge, it would form a small triangular shape, and not affect air flow at all.

 

Seems like y'all have things under control over here in pellet land...I'll just crawl back in my log now...