The “Dutch Oven” design.
The “Dutch Oven” or “Wet Leg” design is a concept where you completely surround the firebox with the cooling water heat exchange medium.
- Eliminate the need for firetubes.
- Prevent damage from overheating.
- Increase efficiency.
Firetubes can be very effective on a conventional oil fired boiler, but on a wood burning boiler a firetube design can quickly evolve into a nightmare. Because soot and ash are a constant part of the wood combustion process, firetubes can easily become dirty, or worse yet plugged completely. This means that the unit will require constant attention and care to keep it operating effectively. Because of its “wet leg” or “dutch oven” design, the Benjamin CC500 combination boiler does not require firetubes. The “firetube wood combustion application” headaches are eliminated, making it much easier to clean, and a delight to operate.
Damage from overheating
Because both the wood and oil fireboxes are completely surrounded with water, the temperature of the steel can never really exceed that of the water on the other side. This prevents a dangerous overheating condition that can potentially damage your boiler, your entire system, or possibly even your home.
If you were going to heat water on your stove top how would you go about it? I suspect that you would put it into a container, and then set that container over a flame. You can’t get much more efficient than that…Unless you could figure out a way to contain the fire inside of the water, then you would have something, as very few of the BTUs from the flame would be able to escape to the ambient air.