Wood stove hot water heaters have started gaining popularity again, especially in Northern parts of United States owing to spiraling prices of Oil and Gas based fuels. The rise in prices and the fact that most of the fuels used for heating today are non-renewable has forced many people to look at alternatives, which are renewable in nature like firewood, corn or wood pellets. While there was skepticism initially about the use of wood stoves and boilers, EPA’s support has helped many manufacturers to come up with highly efficient yet cost effective designs.
Another advantage of using a wood burning stove or boiler unit is that it eliminates the need for indoor heating and helps prevent various kinds of breathing related ailments caused by inhaling particulate matter like ash and harmful gases like Carbon monoxide and Carbon dioxide. An outdoor wood burning stove or furnace for this particular reason is well suited and placed at least 30 feet away from the house.
How it works? Well, wood or wooden pellets or corn is fed into the boiler and allowed to burn at a controlled rate by automatically manipulating the rate of air flow and temperature of fluid flowing in the jacket of the boiler. This jacket consists of pipes filled with water or glycol based liquid on the outer surface of the boiler. The heat produced by combustion of wood inside the boiler is picked up by the fluid flowing inside the jacket and is then transferred via underground insulated pipes to a heat exchanger which further transfers the heat to the desired areas.
Now where at all can such a system be used? Well, it can be used in domestic as well as smaller commercial establishments where maximum pressure never exceeds 435psig and the maximum operating temperature remains below 430F.
So what role does a wood stove heat exchanger play here? It is highly efficient and compact and therefore best suited for smaller establishments and domestic usage. The heated fluid cannot be mixed with the drinking water supply or the domestic water tank for obvious reasons. However, by using a wood stove heat exchanger, one can effectively and safely transfer the heat from hot fluid coming from the boiler to heat drinking water supply or water tank. During the heat exchange process heated fluid flows inside the wood stove heat exchanger form one end and colder fluid from the other. The highly brazed surfaces of the plates of this heat exchanger create maximum turbulence in the flowing fluids and therefore allows for maximum transfer of heat without any physical contact between the two.
One of the major problems that are resolved by using a brazed plate type heat exchanger is that of the pressure difference between the outer loop (boiler) and inner loop (home). The outer loop is generally non-pressurized (maintained at atmospheric pressure) whereas the inner loop is pressurized. Another huge advantage that a wood stove heat exchanger enjoys over some of the traditional heat exchangers like tube and shell heat exchangers is that of the space requirement which in case of the former can be as little as 1/6 of the latter of similar capacity. Needless to say, a wood stove heat exchanger is safer and easier to maintain too.
A wood stove heat exchanger helps in quick transfer of heat from the outdoor boiler and then sends back the colder water for reheating. Most of the wood stove based boilers today come equipped with thermostats and similar devices. These devices help in controlling the temperature, ensuring uniform heating throughout the day and in increasing the efficiency of the entire setup resulting in savings on energy and heating costs. It has been estimated that savings of up to 70% in domestic heating costs can be achieved by using a wood stove heat exchanger along with an outdoor wood burning stove or wood furnace when compared with the more commonly used oil or propane fired boilers using traditional heat exchangers.