What kind of wizardry allows fires to burn in both the upper and lower chambers of a fireplace?
The highly technical burn system in the Twinfire wood stove from Wittus involves convection fans and baffles that direct gasses from the primary burn chamber into the lower chamber for a secondary burn. The system gives the stove a 93 percent efficiency rating, rivaling new furnaces and gas heaters.
Its looks have got the notice of such venerable publications as The New Yorker, and its efficiency makes it the darling of the green set. But the price $6,000 to $10,000 coupled with very specific burning requirements make the Twinfire more of a stove for the casual user than a working whole house heater.
Very dry hardwood is not only recommended, it's required. Elm, oak, ash, maple and beech are the preferred species. Wood at the recommended moisture content of less than 20 percent has to be cut, split and aged for one to two years in a dry, covered location.
Unlike stoves designed to burn overnight or for other extended periods of time, this stove needs frequent tending. The manufacturer recommends no more than three to four pounds of wood at a time about two pieces of cut, split and dried logs. The stove must be carefully reloaded, both because of the danger of falling embers and to avoid introducing too much air too quickly into the fire.
The stove can't be damped down for a long untended burn. That will damage the unit. And if your chimney is too cold you'll have to feed small pieces of wood into the fire box for one to two hours before the stove will draft properly.
The manufacturer acknowledges that the stove is designed more for the casual user than someone trying to heat a house.
Imagine it in a penthouse apartment or an elegant mountain vacation home where it can provide a dramatic design statement as well as some heat.