Indoor wood and pellet boilers are widespread in Europe and are steadily gaining in popularity in the US. Indoor wood boilers have been used in America for many decades, but they tend to be a more basic technology that is not very efficient or clean. Modern, automated pellet boilers (hot water) and furnaces (hot air) using bulk pellets offer homeowners virtually the same convenience as a fossil fuel furnace by feeding fuel automatically from a large storage area. Both New Hampshire and Massachusetts offer generous rebates to install these systems.
|Modern indoor wood boilers can have oxygen sensors, microprocessors, and catalyst capabilities. This allows them to achieve very high efficiencies, in the mid 80s, HHV. They need to be loaded once or twice a day and hot water storage tanks ensure that they burn as cleanly and efficiently as possible. Hot water storage allows the full load of fuel to be completely burned, while extra heat is stored in the tank. This prevents the boiler from cycling on and off.|
|Modern pellet boilers and furnaces also have automated sensors to control combustion, along with automated fuel loading so that the operator may only need to clean out the ash tray once or twice a month. Pellet boilers and furnaces can be loaded daily with 40-pound bags of pellets, just like stoves. They may also have a bulk storage bin that holds several tons of pellets and is only refilled once or twice a winter.|