Help in understanding Ecxel Chimney please

[holg]

O.K. This question comes under the heading of something that doesn't jive with my previous understanding of things, but I know my previous understanding of many things is flawed. I have searched for similar posts on this subject, and in reading replies to turbocruiser's post of earlier this month regarding chimney pipe comparisons, I did learn a few things.

As for my "previous understanding": I was under the assumption that one ALWAYS had to maintain 2" from class A chimney pipe to combustibles such as ceiling joists.
I will be putting in Excel's class A 6" insulated chimney pipe for my new Heritage. In looking at the square support box that extends into the living area from my attic, I notice that the clearance from the outer edge of the actual pipe is ~ 1 inch to the square support box that will presumably contact framed joists in the ceiling. Reading their instruction manual, this information is verified.
Knowing that Excel has one of the really good reputations out there, and believing I am correct in understanding that they have met the U.S. and Canadian standards, I suppose I should say, "good enough". Has anyone else had to rethink what they thought they knew on standard clearances? Or does anyone care to shed a little light on presumably when 2 inch clearances were changed dependent upon testing results?

Thanks.

 

[oldspark]

Excel is the only one that has the 1 inch clearance I believe, all others are the 2 inch.

 

[Delta-T]

i think that the 2" is the standard, and Excell went out of their way to design and have certified, the round and square supports for the specific purpose of reduced clearance. I'm not sure when this happened, just that it happened. The 2" clearance is still the "norm" and should be followed, UNLESS there is a specific reference to reduced clearance certification.

 

[Wood Heat Stoves]

Clearances can be less when the pipe is inside it's own support box. Another example would be 8" ID Dura Chimney which is 12" OD. The support box is 14 1/4 " square to fit in between standard 16" on center supports. That only gives a 1" clearance on both sides even though the clearance on Dura Chimney is 2". It's OK because it's been tested in this configuration and you're OK as long as you use all the same brand components and you install it according to the chimneys installation instructions.

 

[summit]

1" only if using the support box, or radiation shield, or ITH, or the many other firestops/supports the have devised... but to bare naked excel pipe it is 2".

 

[holg]

Thanks to old spark, Delta-T, Wood Heat Stoves and summit for the responses. I've been educated and again feel good regarding my decision to go with the Excel system. As it's been 80s and 90s around here, I don't think I'll be testing out the system for awhile.

 

[oldspark]

One things for sure you cant go wrong with that brand, happy heating.