Mixing 3 and 4" pellet vent pipe....better or worse?

[scdngy]

It's become obvious from reading here at Hearth.com that a 4" vent will aid in creating a draft and a good burn when electric power is unavailable. However, i have a tight install to make therefore 3" pipe would work better for locating the stove. So....are there any benefits when power is unavailable if i use 3" pvp for the first leg and then convert to 4" about 8' up, and run the last 15' with 4"? Thanks for any feedback.

 

[johneh]

Don't know if there is a benefit to what you propose but my stove goes from to 3in double-walled
pipe a class to a class A 6in chimney and I have never had a smoke problem. I live in an area that has
more than its share of power failures.

 

[Washed-Up]

4” is better draft yes…but I’ve used 3” on my personal and 4” on a couple installs…They both work and I’ve seen no negatives on a 16’ 3” run…I would go 3” the whole way if it were me