Hi Hearthman,
Thank you for responding.
Hearthman wrote:Actually, the answer is right under our noses. IFGC 503.5.4 Chimney terminations ....."and is at least 2 feet (610 mm) higher than any portion of a building within a horizontal distance of 10 feet (3048 mm)."
However, I have a question: The IFGC does not apply to single-family dwelling units and that is not a chimney, thus does that still apply?
The IRC for Type B Gas vents has different requirements, and does not specifically state the same as for chimneys.
We tend to think of this rule pertaining just to adjacent gable walls and such but it includes roof turbines because they are a "portion of a building". By locating 2 feet above this feature of the building, you get the flue gas outlet into clear, undisturbed wind and above this opening.
Thus, my referencing the IRC requirements for Type B Gas Vents being 8 feet from vertical obstructions would pertain as well? I was not sure if they would.
Though turbines normally exhaust, all it takes is a wind eddy to recirculate air. By maintaining this separation, you should reasonably prevent recirculation of flue gases.
That was my concern, yes.
Now, if you want, you could cite an ASHRAE Standard, 62.1, Ch. 5 that deals with such separations from 'hazardous exhausts' at a min. 15ft for normally bad stuff and 30 ft. separation for extra bad stuff. Based upon personal experience, I find the 2/10 rule sufficient.
Okay, now you are getting into what really might help!
Here is another question, that references "hazardous exhausts", what defines an "exhaust"? In the IRC it refers to mechanically exhausted exhausts, and a Type B gas vent is simply a hole up through the structure which vents stuff out by gravity. Is a Type B gas vent considered an "exhaust"?
If so, then the IRC "Exhaust Systems" would address this:
- From the 2006 IRC. (underlining and bold are mine)
- - M1501.1
Outdoor discharge. The air removed by every mechanical exhaust system shall be discharged to the outdoors. Air shall not be exhausted into an attic, soffit, ridge vent or crawl space.
- - - Exception: Whole-house ventilation-type attic fans that discharge into the attic space of dwelling units having private attics shall be permitted.
However, that again refers to "mechanical" exhausts.