Thanks for the suggestion...just sent an inquiry off to them.tutu_sue said:Email Lehman's at [email protected] about the short leg kit. Tell them there is nothing in the manual about the R-value with short legs, but you need to be sure. They will ask Jotul directly and get back to you.
So far here is my train of thought: If I'm taking away 2.25 of air space then that is removing the equivalent of R=3.2175. With that mentality (lots of people think I'm a mental case, anyhoo...) then I will need the prescribed R=1.1 value PLUS the R=3.2175 value that was taken away by removing the 2.25" of air space. This is kind of like the Chinese do...reverse engineer it.
The original configuration:
F3CB Requirements
Tall Legs Inches R-Value
Required ? 1.10
Air Space (ventilated) 1.00 1.43
Air Space (ventilated) 1.00 1.43
Air Space (ventilated) 0.25 0.36
Totals 2.25 4.32
These are the clearances that I came up with between the top of the rear exit flue and the lintel:
Height Height
F3CB Tall Legs Short Legs
Lintel 27.00 27.00
Top of Flue -25.56 -23.31
Flue Clearance/
Hearth Thickness 1.44" 3.69"
And this is what I think it would take to get to the required R=4.32 which would leave roughly .6" clearance between lintel and pipe...might be enough for double-wall pipe?:
Inches R-Value
Ceramic Tile 0.25 0.01
Cement/Thinset 0.25 0.05
Durock Cement Board 0.50 0.26
Ceramic Board (Micore) 0.50 1.10
Ceramic Board (Micore) 0.50 1.10
Ceramic Board (Micore) 0.50 1.10
Ceramic Board (Micore) 0.50 1.10
3.00" R= 4.72
Maybe that wasn't too confusing, but I think that would work. Is having 2 inches of micor too much in regards to structural integrity (will it mash/sag)?
Ah, well I see the formating didn't work out very well...
Again...clear as mud,
Ed
....one cell at a time.