Rasmussen nominal log set sizes are based on the approximate length of the front log (or combined length of two-piece front logs) of the set. Heights of the log sets vary based on the multiple ways of stacking the top logs.

Minimum Depths for vented log sets are:

13" "F" Flaming Ember Burner Sets
15" "FX" Flaming Ember XTRA Burner Sets (12" to 30" set sizes)
18" "FX" Flaming Ember XTRA Burner Sets (33" and larger set sizes)
13" "CS" and "CA" Custom Pan Burner Sets
12" "CXF" Custom Embers Pan Burner Sets (12" and 15" set sizes)
14" "CXF" Custom Embers Pan Burner Sets (18" - 30" set sizes)
16" "CXF" Custom Embers Pan Burner Sets (36" set size)
16" "LC" Multi-burner Sets (18" - 30" set sizes)
20" "LD" Multi-burner Sets (30X set size)
22" "LD" Multi-burner Sets (36" - 96" set size)
12" "TNA" Tipi/Andiron Burner (20"-36" set sizes)
14" "TNA-E" Enhanced Tipi/Andiron Burner (20"-36" set sizes)

 

Minimum Depths for Chillbuster vent-free log sets are:

11" "C1" and "M1" Single Burner Sets
16" "DFC1" Single Burner Sets for See-Through Fireplaces
14" "C2" and "M2" Dual Burner with Embers Sets
14" "C3" Triple Burner with Embers Sets
14" "C5" Triple Burner with Embers Sets
12" "C7" Single Burner with Embers sets
16" "DFC7" Single Burner with Embers sets for See-Through Fireplaces
14" "C8" Single Burner with Embers sets (minimum 22" rear width)
9" "C9" Dual Burner CoalFire Sets (C9A=16" front width; C9B=20" front width)
14" "CR" Dual Burner with Infrared sets

 

Minumum Depths for Alterna vent-free sets are:

11" All Single Sided Sets
13" All Double Sided Sets

 

Another consideration is the location of the gas supply line. In most fireplaces the gas supply enters from the side wall. Entering from the floor can be problematic if in the center of the fireplace. If this is so, the CS on legs (2.25" clearance underneath the pan) and LC (due to the open space underneath the rear burner) burners may be the only viable burner options.