Three-Sided Fireplace: Gas vs. Wood, Venting and Placement

A three-sided fireplace, also called a peninsula fireplace, has glass on the front and both ends so the fire can be seen from three directions. It works as a room divider or the centerpiece of an open floor plan. Nearly all three-sided fireplaces sold today are sealed, direct-vent gas units, because an open wood fire with three open sides is very hard to make draw without smoking the room.

Why most are gas

A traditional open fireplace works because smoke rises and the chimney pulls room air in through the opening, carrying smoke up. The bigger the opening, the more air the chimney has to move to keep smoke from spilling out. Open the fireplace on three sides and the opening becomes huge, while side drafts push smoke sideways. Wood-burning peninsula fireplaces exist, but they need large flues, careful design and often glass doors to work.

A direct-vent gas three-sided fireplace avoids all of that. The firebox is sealed behind glass. A coaxial vent pipe pulls outside air in for combustion and sends exhaust out through the same pipe, through a wall or the roof. Room air isn't involved, so drafts and smoke spill aren't a concern.

Gas vs. wood at a glance

	Direct-vent gas	Wood-burning
Glass	Sealed glass on all three sides	Open or with doors
Venting	Coaxial pipe through wall or roof	Large masonry or factory-built chimney
Efficiency	Can heat the room	Mostly ambiance; loses heat up the flue
Maintenance	Annual service	Ash, sweeping, firewood
Install flexibility	High; can go almost anywhere a vent can run	Low

Venting and placement

• Vent route: direct-vent units can often vent horizontally through an outside wall within a set distance, or vertically through the roof. The maker's manual lists maximum vent lengths and the number of elbows allowed.
• Placement: peninsula units usually sit at the end of a short wall that juts into the room, so the back is against framing and three sides face out.
• Clearances: mantels, shelves and TVs above the unit need the clearances in the installation manual. Glass on three sides means heat radiates in three directions; plan seating accordingly.
• Glass safety: fireplace glass gets very hot. Since 2015, U.S. gas fireplaces with glass fronts are required to come with a safety barrier screen. Keep it on if there are kids or pets.

Cost factors

The unit's price depends on size and features, and installation often costs as much as the unit, especially when a gas line, framing, venting through the roof and finished surround are involved. Get quotes that include all of it: gas line, venting, framing, electrical (for the fan and ignition), finish materials and permit.

Questions to ask before you buy

1. Is the unit direct-vent, and can it vent where the house allows?
2. What's the heat output range, and is it right for the room size?
3. Does it have a variable flame and a fan, and does it need electricity to run in a power outage?
4. What's the warranty on the burner and the glass?
5. How often does it need service, and who services that brand locally?

If you want a wood fire, a conventional one-sided masonry fireplace or a wood stove will heat better and draw more reliably.