Newly patented technology has improved the energy efficiency of natural gas fireplaces. Rated at 93% efficient in the government’s Annual Fuel Utilization Efficiency standard (AFUE), the new Mantis™ fireplace from Empire Comfort Systems combines the aesthetics of a gas fireplace with the efficiency of a modern furnace. Compared to a conventional direct-vent supplemental heating system, which achieves an average of 64 percent AFUE, this new technology can help save you up to $200 each year.*
The heart of this new technology is the three-stage heat exchanger:
Stage one is the firebox itself, where the temperature range can reach 750 to 900 degrees F. Ceramic glass at the front of fireplace helps transfer this heat into the room, while forced air circulation around the outside of the rugged steel firebox carries more heat to the room.
Stage two is a large diameter marine-grade stainless steel tube that carries the flue products out of the firebox. Its corrugated walls enhance turbulence, which helps transfer heat.
Stage three consists of multiple small diameter stainless steel tubes with internal turbulence generators and external fins that wring the last of the heat from the exhaust before it exits the fireplace.
The unit is so adept at drawing all the heat out of every drop of gas, that the exhaust venting requires the standard 1 1/2-inch PVC pipe. This small-diameter PVC pipe can be routed up a wall and out the roof, down through the floor and out a crawlspace or basement wall, or straight out the back. This versatile PVC venting makes this new technology ideal for sunrooms, cabins, basements, or any installation where a conventional vent pipe is impractical. It’s the first and only condensing vented gas fireplace system certified for use in the United States.
While a conventional fireplace relies on heat rising to carry the flue products out of the room, the Mantis(TM) system cools its exhaust to the point so it does not rise on its own. Instead, a power-vent exhaust blower carries a measured amount of fresh air into the unit to support combustion, and carries the flue products to the outdoors. This precise air-to-gas ration ensures a clean-burn for lower emissions.
For added efficiency, this new design eliminates the need for a standing pilot, and relies instead on a hot surface ignition system. When the unit cycles on, the vent blower runs for 40 seconds to purge any unburned gases from the firebox. After the purge, the ignitors begin to glow and the gas valve opens to create one clean-burning fire.
Moisture, which is present in any combustion product (wood, pellet, or gas-fired), condenses out of the exhaust and is captured in a holding tank. A built-in pump moves this distilled water onto a tray above the firebox, where heat and air circulation evaporate it to add moisture to the air. The result is increased room humidity during the dry winter months.
The Mantis does not carry an Energy Star rating. The reason? It is so new to the U.S. market that it doesn’t fit any Energy Star category. However, it outperforms most Energy Star rated central furnaces in heat transfer efficency. In Australia, the Mantis earns a 5.52 out of 6.0 on that country’s Star Rating system. No vented zone heating system – U.S. or Australian – outperforms it.
*Based on natural gas cost of $1.00 per therm; heating efficiency rating AFUE of 93% (Mantis) vs. 64% (conventional); cost per million btu input of $10.00 over the course of a heating season.