Over a thirty year period there have been many manufacturers of outdoor furnaces. An outdoor furnace is simply a structure that burns wood and heats hot water. This in turn is circulated to and from buildings and equipment that require heat. Many early models had what is called a natural draft air feed. This method caused a slow and cold burn of the fuel. The early versions also surrounded the fire with a water jacket that also created a colder burn. These two designs would then create heavy amounts of exhausted smoke and use large fuel consumption.
As time passed, an air injection fan was incorporated and controlled by an aqua stat. This improved the burn by increasing the oxygen to the fire but the water surrounding it still created some cooling effect. When an outdoor furnace is filled, the wood is often at outside temperatures and until it heats up, it will also add to what is know as a cold fire dirty burn.
This industry is evolving with the development of models of a third generation class of outdoor are a wood gasification, indoor/outdoor hot water wood furnace. How this class of furnace differs from past outdoor furnaces is that they have fire bricks incorporated into their burn chamber design. The fire bricks can reach temperatures of 1700F thus burning off the gasses and smoke. In doing this gasification properly, the manufacturer is able to obtain an EPA Phase 2 qualification. This means that the particulate matter leaving the furnace is extremely low. This creates a highly efficient and clean burn that is very desirable for owners and neighbours alike.
There are models of this class of furnace that have a rating of 160,000 BTU maximum output and have acquired a heat transfer efficiency of 88.4%. Another larger model has a 200,000 BTU maximum rating with a heat transfer efficiency of 90.1%. These models have the ability to adjust the BTU output with ease, to suit seasonal heat loads and wood types. This creates a simple design that is reliable and user friendly while setting a new benchmark for performance in efficiency and reduced emissions for an outdoor furnace.
Some of the leaders in this industry have been testing their newer models to the most recent test criteria (EPA Test Method 28 WHH For measurement of Particulate Emissions and Heating Efficiency of Outdoor Wood-Fired Hydronic Heating Appliances). These results are of a more accurate and realistic nature that in turn relate to actual outputs, burn time expectations and emissions of an outdoor furnace.
These leading manufacturers are an EPA Hydronic Heater Voluntary Program Phase 2 Partner.
In supporting this initiative it improves the outdoor furnace industry and what it has to offer to the general public. This is a safe alternative heating option using wood that is a less costly fuel, that is carbon neutral and a renewable resource.
This product can heat your home, domestic hot water, garage, workshop, swimming pool, hot tub and greenhouse all with one properly sized unit.
This type of hot water wood furnace can be connected to any type of existing heating system by means of Pex piping, water to water or water to air exchangers and a low power usage circulation pump(s).
In these economic times, the implementation of indoor/outdoor hot water wood heating can be a financially viable and environmentally friendly alternative method of heating.