The WK400′s unique wood combustion chamber.
- It’s oval shaped.
- It’s lacks firebricks or wood grates.
- It’s thoughtful design and construction.
Hand welded, and constructed of 11 gauge, 1/8″ thick steel, the combustion chamber is the heart of the unit. It measures 18″ High, 21″ wide, and 24″ deep (This means that it can handle more than one 24″ log!)
As you may already know, smoke contains much of the wood’s total energy, and will spiral by it’s very nature. Benjamin has built a uniquely different combustion chamber and heat exchanger that facilitates that effect. A conventional square combustion chamber, or box frame heat exchanger restricts this natural flow. The smoke will rise up to the corners and swirl around there, cooling as it does so. This cooling process allows creosote and soot to form on these surfaces. They act as an insulator, and restrict the ability of the combustion chamber and heat exchanger. Benjamin’s oval combustion chamber design allows the smoke to spiral and release it’s heat cleanly and efficiently.
The oval design also eliminates the need for firebricks or wood grates. These were also found to reduce efficiency. Wood grates will allow too much combustion air to enter under your burning wood. Your wood will be consumed ineffectively and the heat will go up your chimney, instead of into your home. Firebrick, in essence, will do the same thing. BTUs and time will be lost as the unit is forced to heat the unneeded thermal mass.
Maine Wood Furnaces have a better idea.
We want you to always keep a layer of coals and ash in the base of the wood burning combustion chamber. These are to be used in place of the conventional wood grates or firebrick. This will slow your wood burn down to a manageable level, allowing you to effectively remove heat from all three of the stages of combustion, and it will allow the smoke to do what it wants to do naturally.
Also note that the door to access the wood burning chamber is made out of cast iron. Benjamin is one of the few remaining wood burning manufacturers that still utilize a cast iron door. They do this because the cast iron will not flex the way a steel door will. This ensures a tight gasket seal and a reduction in lost BTUs due to a constant air leak draft.