Pardon the crap tastic drawing, forgot AutoCAD isn't installed yet and I suck with photoshop lol.

As shown in the picture...
I've always heard from manufacturers that all venting must slope towards the unit, and option #2 was the only pictures they had (providing you don't just come straight out, or into some form of termination kit).

Today I was told that option #1 will work, and also told option #1 will freeze up. The lenth of the run outside of the house isn't very far, lets say around 12" or less for the sake of using numbers.

Option #1, everything slopes towards the unit (inside) accept for the last short run thats outside (after the last elbow), that length of pipe slopes away from the house to allow everything to drain out of the pipe.

Option #2, everything slopes towards the unit (inside) all the way.

Lets also throw in the variable of either both ways insulated, or both ways uninsulated.

Answer options, will work, will work but it's right, won't work, or any variety inbetween.

I know there are many answers that aren't right, but aren't really wrong, just bad practice. I'm curious to see what ya pro's have to say.

My personal answer is #2 is best (since I've seen it in so many installation books), but #1 would work in a pinch. I really don't see it icing up too bad if it's a short run.

Thanks fellas and ladies.

[Edited by amickracing on 01-26-2005 at 07:07 PM]