Simple! The interior workings of the outdoor wood furnace consist of a firebox, and within the firebox is a chimney, a grate with a powered blower that forces air up into the fire for a greater and more efficient burn. Wood is loaded into the firebox the same way as a traditional fireplace.
Surrounding the firebox is at least a 120 gallon water jacket.The wood is burned in the firebox, thereby heating the water in the surrounding water jacket.
A pump at the back of the outdoor boiler sends the heated water on a continuous loop to the house through an insulated PEX line to a heat exchanger on your furnace and the water heater inside your home, then back again for reheating.
More connections can be made to heat a pool, a sauna, a hot tub, a garage and other buildings. For this, a second pump would be installed and a second set of PEX lines would be connected to the outdoor furnace for running to another heating load. Insulation surrounds the water jacket so that the water temperature is not compromised by weather.
The firebox is surrounded by water along with the ash pan and a portion of the chimney as well, extracting as much heat as possible from the red hot coals. The chimney protrudes down into the firebox about 1 foot from the bottom so that smoke, and more importantly heat, is trapped so it doesn’t quickly escape out the flue. This also creates a second burn sequence to more completely burn the gases and wood. Efficient design ideas with proven results!
A wood BBQ pellet is a small, 1 inch long, 1/4 inch diameter piece of hardwood. Because of their small size, wood pellets burn cleanly and quickly to a fine ash. Wood pellets burn at about 8,500 BTUs per pound. Wood pellets come in a wide variety of “flavors” ranging from hickory and oak to cherry, apple or maple. The pellets in a normal pellet grill are fed from a storage hopper to a burning box at a controlled rate. This rate is adjustable based on whether you want a high temperature for grilling or a low temperature for smoking.
Because of the automated feed of the wood pellets you can literally turn the unit on, give it 10 to 15 minutes to heat up, and be ready to grill in almost no time. This makes it as convenient as a gas grill but with the added flavor of hardwood cooking.
Automation is also great when it comes to smoking. You can smoke for hours in a temperature controlled environment with little work from you. It is also virtually impossible to get a flare-up on a pellet grill. On high a pellet grill will consume about 2 pounds per hour. This would be the temperature you grill steaks and burgers at, You probably wouldn’t want to have the unit running for a full hour. On the smoke setting it will consume about 1/2-pound per hour so if you plan on smoking for 10 hours you will use 5 pounds of pellets.