How to heat water with a woodstove, - the Safe way!
Coils placed inside the firebox of a woodstove are exposed to high temperatures and corrosive agents. The high temperatures can in some situations create very high pressures inside the water coils. Results can be catastrophic. Coils attached to a woodstove most likely invalidate EPA/CSA certifications. Heat-Booster Energy Systems have developed a method for collecting hot air from sides, top and rear of woodstoves. This is done by enclosing the woodstove in a sheet metal "box". A specially designed finned coil heat exchanger is then attached to the rear of the box. The hot air is drawn downwards through the heat exchanger using a high quality in-line blower. Water is circulated through the heat exchanger to a tank or hydronic heating system. A thermostat (temperature controller) can be used to control blower and circulating pump. Stop blower to stop heat transfer. It is as simple as that. Temperatures in heat exchanger cannot get high enough to create excessive pressures. Most of the heat from a woodstove can be captured for water heating purposes. Radiant energy from bottom and front of stove will not be available for water heating. Stoves operated at high burning rates lose heat via hot flue gases. This wasted energy can be used for water heating by installing a Heat-Booster with a heat exchanger. A Draft-Booster (a Draft-Inducer) is often required to compensate for reduced chimney draft resulting from cooler flue gases.
Combine the two different water heating systems if needed. Up to 75% of the heat from a woodstove can be captured and transferred to water. The high efficiency finned coil has a 7 m² heat transfer area. This allows you to capture the heat off the largest woodstoves. The heat transfer coefficient for air to finned coils is in the 284 W/m²·℃ range where ∆T is the temperature difference of the hot air and the water in the coil.
Thermal efficiency (%)=100×(T₁-T₂)/T₁ where T is in Kelvin. ℃+273=K
The water heating systems are custom built. Price is USD 795.00 plus shipping and handling. Any applicable taxes are extra.
