flue question

[juniorbill]

We're adding a 2nd story onto our house and will be having a second HVAC system installed to service it. However, the flue from the existing system comes through the roof at a part of the first floor that is behind the 2nd-story addition by about 5 feet. I know we'll have to do something to change that because it's within 10 feet of the new 2nd-story wall. That section of the house has an attic that's about 3 feet high. I'd like to be able to reroute the flue to a new chase in the 2nd floor, but it would require an angled run between the run from the basement to above the first-floor ceiling and the run up the 2nd floor. ... I'm sorry I'm having trouble explaining this. My question is, can a near-horizontal run of flue be put between two long vertical runs, as long as it slopes at least 1/4" per foot? We would have the HVAC contractor handle it, but we're framing up the 2nd floor and I want to have an idea about how to handle this.

Here's the idea:


http://us.f13.yahoofs.com/bc/43eb9606m3090e92c/bc/images/flue.GIF?BCfaPpGBs_MhBIoK

[RoBoTeq]

That should not be a problem at all as long as all flue piping is of the same material and type.

[firecontrol]

You should be involving your HVAC contractor now before you start pounding nails. There might be an isssue later as far as the venting is concerned that would be very easy to solve now, but impossible or very expensive later.

[contactor]

How long will horizontal be ? Our type B vent manufacturer instr. state to keep main vent offsets as close to 45 deg as possible. Under 45 is a lateral run that should not exceed 1 1/2 times length in feet, of vent diameter in inches. (ie. a 4" vent can't exceed 6' lateral.), and reduces vent capacity by 20%. Added height will increase capacity.
You should really get a contractor to properly size and install new vent system.

[juniorbill]

Thanks for the input. It sounds like it will be doable based on our situation. I'll give the HVAC contractor a call in the morning to discuss specifics.