The in-wall fireplace you're looking for may well be closer than you think. In fact, it can be something like this Tahoe Deluxe Clean Face Direct Vent Gas Fireplace that has all of the heating capacity, and lots of other useful features to boot.
This unit features a realistic six-piece log set, a large heat-resistant tempered glass viewing window, and remote-ready millivolt controls that make operation easy. As stated, the fireplace can be installed in a wall, plus it can operate without electricity and has a contour burner that generates up to 20,000 BTU's for your home's comfort.
There's also a discreet air distribution channel that eliminates the need for louvers but allows for the use of an optional blower. Add in heater-rated design and a 3-year limited warranty, and you come up with a package that has all of the heating strength you need and a fantastic in-wall look you'll love.
Features
Realistic six-piece log set
Contour burner generates up to 20,000 BTUs with an 82% steady state efficiency
Large heat-resistant tempered glass viewing window
Discreet air distribution channel eliminates the need for louvers, yet still allows use of an optional blower
Convenient in-wall installation
User-friendly direct ignition
Can use natural gas or propane - arrives as a natural gas unit, but includes a propane conversion kit
Heater-rated design
Hem-bent seams replace unreliable screws and fasteners
Uses 4" x 6 5/8" diameter vent pipe
3-year limited warranty
Approximate Dimensions: 37" W x 35 5/8" H x 16 3/8" D