For your extra-large existing fireplace, select the Jackson XXL insert. All the terrific features of our other 2 gas inserts with a 21" x 35" glass size! With numerous customizing options, you're to sure to complement your decor.

40,900 BTU/hr Input-NG High Efficiency: 80%   39,700 BTU/hr Input-LP High Efficiency: 80%   High Quality Lifetime Borofloat Glass (21" x 35")   Quick-Latch Glass with Standard Arched Valance   Seasonal Heat-Dump Baffle   Co-linear Air Duct (Manifold)   Seasonal Heat-Dump Baffle   Millivolt board with 30 second delay   Patented burner & log design   Refractory Firebrick Panels (Back & Sides)   Automatic fan (2-75 CFM) w/variable speed control   Tested to 50 Pascal of negative pressure which passes the Minnesota Energy Code for Residential Ventilation   The highest quality materials and workmanship   Variable heat output control allows you to adjust the flame height and heat output   Limited Lifetime Warranty   Co-linear vent system 25ft. of 4" & 3" flex pipe   Brass, Black, Chrome or Brushed Nickel grills   Arched Valance Brass Glass Trim   Numerous decorative door options   Remote Control or Thermostat Remote Control   Wall-Mount Thermostat (wireless available)   Decorative (Beveled) Paneled Design Glass   3-Piece Shrouds (Masonry Style Only) with On/Off switch mounting hole   Brass, Black, or Chrome Molded Trim for Shrouds   Custom Shrouds (Masonry Style) & custom trim available

From Grill Outlet on the Insert to Combustible Mantel 16"   From Side of the Insert Glass (glazing) to a Side Wall 4.5"

Always consult the installation manual for venting requirements #815-CL Direct Vent Kit - 25 ft. of 3" x 4" Co-linear Vent System - with Termination Cap #510 Extension kit - extends #815-CL up to a max. of 40 ft. Minimum chimney height: 12 ft. Maximum chimney height: 40 ft.