Stack size can I go from 12 to 10

[twitch]

I've got a new to me evaporator coming. It's the very clean 30 x 10 with the steam away that has been in the classified. Very well kept rig. I have a 10 inch double insulated pipe threw my roof already and the evaporator has a 12 inch stack . I not to crazy about ripping my roof apart this time of year . Just wondering how much effect it would have if I come out of evaporator with 12 inch then step down to 10 to go threw the roof. I plan to change it over this summer but would to just plug it in for now. Thanks for any input.

[Woodsrover]

I'll go out on a limb here and say you'll be fine. If you have enough height you'll get enough draft.

[maple flats]

If it doesn't draw enough you have 2 options without going to 12" now. You can add more height or add a blower.
Then next summer make the change. Some 3x10's only had a 10" years ago, in recent years most have gone to a larger stack size because the work better.

[twitch]

The arch has a blower it an older inferno style arch . If 2 other people think it will be fine that's enough for me. Thanks for the reply

[bowhunter]

The velocity through the 10 inch pipe will be about 45% higher than through the 12 inch pipe, so it will make a difference. I think the recommendations to increase the stack height should be enough to overcome a short section of 10 inch.