Fisher Fireplace Insert Project

[coaly]

Hearth requirements are in the manual.
The 1 1/2" clearance under ash fender is the blower air intake space to prevent the slot under the Insert from obstruction.

 

[arodrigz]

Hearth requirements are in the manual.
The 1 1/2" clearance under ash fender is the blower air intake space to prevent the slot under the Insert from obstruction.

Yep, read those. It says "3/4" min thickness asbestos millboard or equivalent. If asbestos millboard is used, a noncombustible material such as tile or brick can be placed over it for decoration." I'm not familiar with asbestos millboard but I'm going to assume that concrete board or hardibacker board are the equivalent. If so, I'm ok, if not, someone let me know

 

[coaly]

The benchmark standard of 3/8" asbestos millboard is a common requirement used by many manufacturers with a k-value of 0.84. (R .45) Many materials are rated by R value (higher better) and must be converted to k, (lower better) but it doesn't look like you will be able to tell what the value of the material you have is anyway. (double k value of .84 is .42, double R value of .45 is .90 so that gives you an idea of what you need)
Thermal resistance and thermal conductivity are the different properties materials are tested by, so it's not a simple answer. Here's an article with table of common materials to give you an idea of what the value of your material is;
https://www.hearth.com/econtent/index.php/articles/k_values_what_does_it_all_mean

 

[arodrigz]

Thanks for the great info

 

[BigZ_87]

Mine measures 6" wide x 24 3/4" long with about 2" left for the flat mounting to the top of the insert.

 

[arodrigz]

Mine measures 6" wide x 24 3/4" long with about 2" left for the flat mounting to the top of the insert.

View attachment 127815

Thanks again. Much appreciated.