Low point allowed in boiler vent / intake lines? (water collection)

Hi all. Per the image below, is a low point allowed in a boiler vent or intake run? I'm concerned about the possibility of water collecting at this point and obstructing air flow.

The boiler, a TriangleTube Prestige 110, is on the 1st floor, with parallel 3" PVC snaking its way up three floors to a rooftop combo vent / intake.

In the photo, I've put together mock-up: the vent line penetrates through the top plate of a wall on the left, uses dual 22° fittings to duck under some roof framing members that cross the joist bay, then makes a 90° turn and continues climbing to the floor above.

The horizontal section in the middle of the photo is a low point, and could trap and hold water.

Do these lines have a slope requirement? Is this "trap" allowed? If so, is it permissible for me to add a drain to it?

As always, thanks for any and all input.

http://www.booboodog.net/images/hous...oiler-vent.jpg

The installation instruction book should say. Most I've looked at require there be a constant slope like a drain line so any condensation or rain water can drain to the drain point. So, yes, I think you may have problems with this.

Also, the instructions will say what the limits are in length. Each elbow shortens the effective length. You need to ensure you stay within the specs on length as well.

Quote:

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Originally Posted by jadnashua

The installation instruction book should say. Most I've looked at require there be a constant slope like a drain line so any condensation or rain water can drain to the drain point. So, yes, I think you may have problems with this.

Also, the instructions will say what the limits are in length. Each elbow shortens the effective length. You need to ensure you stay within the specs on length as well.

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Thanks, Jim. I just searched through the install PDF again and can't find any reference to slope, but nevertheless I'll keep working on finding a way around this unless somebody else here can tell me otherwise.

BTW, run length & # of bends are good! At least, per the standards my plumber provided.

Ok, so I basically just cut 4" holes into my 2x4 framing in order to fit those 90's into the actual wall (using the term "fit" very loosely -- or tightly, as it were). Yeah, it's ugly, but I'll be able to rock around the protrusions after my inspector is done criticizing my mess.

Curses to my architect who designed a concrete-walled basement mechanical room with no provisions for clothes dryer or boiler venting, nor floor and condensate drains. *sigh*