3 inch or 4 inch exhaust liner?

[pelletshopper]

I am considering purchasing an Enviro EF3 pellet insert. The dealer told me that he does all his installs with 3 inch exhaust liner, regardless of height. He says that a 4 inch liner creates draft problems on all pellet stoves. Most manufacturers recommend 4 inch liner for installs exceeding 15 feet. The EF3 manual just says to use 3 inch or 4 inch liner and does not mention height. The height of my install will be about 25 feet. Who's correct? The installer or the manufacturers?

 

[Wet1]

You'll have to have at least one 90* in there, in addition to that 25', so I'd most certainly use 4".

 

[BrotherBart]

The particulars of an installation exactly like you are talking about are discussed in the last example at the bottom of the page here:

http://www.nevelsstoves.com/articles/Venting-your-pellet-stove.htm

Use four inch liner to reduce the frictional resistance of the liner to the positive exhaust pressure from the insert.