Burning firewood has been used as a primary heat source by humans for millennia, yet until the invention of a reliable combustion chamber e.g. the wood burning stove, much of this heat was lost to the environment.
In 1646 the first US foundry began the production of wood stoves, which would be one of the first steps on the road to improving the efficiency of wood heat. Stoves provided the means to trap the heat for longer, and the metal casing conducted the heat allowing it to more slowly radiate into the surrounding space, practically revolutionizing how people heated their homes.
To this day, the wood heat technology revolution continues and the first pellet stove was made commercially available in 1983. Pellet technology is seen as a huge innovation to their wood rivals, they are considered safer, more user-friendly and so clean that the EPA doesn’t even monitor their use.
So how do these seemingly complex pellet stoves work? Believe it or not, they work in much the same way as wood burning stoves but have a few important modifications. These, in turn, have provided them with their efficiency, convenience and safety advantages
1. The Hopper
The hopper is usually located at the top of the pellet stove, but sometimes can be found on the side or bottom. Essentially, this is a large storage hold, where pellet stoves are placed and is the first “stop” on the pellets journey through the system.
The average hopper in pellet stoves has a pellet holding capacity of between 40 – 100 pounds of pellets. This means larger stoves will allow more pellets to be stored and therefore fewer refills will be required.
The time the stove takes to use the pellets stored in the hopper is governed by both the size of the hopper and the rate of burn selected. This means if the pellet stove is placed on a high heat output setting it will burn through the store much faster. The typical pellet stove needs to be refueled every few days.
2. The Auger
Another key component of the pellet stove is called the auger system, which is responsible for transporting the pellets from the hopper into the combustion chamber. This could be thought of as the next step of the pellets journey through the system.
Augers vary greatly in their designs but are typically constructed from metal and bear a drill-like spiral design. The auger is powered by a motor, which typically runs off electricity. For this reason, many people don’t see them as a viable off-grid option, but there are more and more models available that now have a battery powered motor instead.
3. The Combustion Chamber
The combustion chamber is where the pellets are set alight and heat production occurs. Inside the chamber is a burn pot in which the pellets are fed and an electrical ignition begins the process of combustion.
Overtime, the burning of the pellets produces waste in the form of ash, which is collected in the burn pot. When full, the ash is emptied, typically this is done using a lever that opens a catch allowing the ash to be deposited into the ash pan underneath.
The combustion chamber is also typically lined with a fireproof material such as fire bricks or a steel lining, although bricks are often preferred as they last much longer. The combustion chamber can be viewed from the outside, with heat proof glass providing a safe barrier.
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4. Heat Exchanger & Convection Blower
A major component of pellet stoves is the heat exchanger and convection blower. In combination, these components allow modern pellet stoves to achieve maximum heat efficiencies up to a considerable 80%.
The convection blower draws cold air from the living space and drives this oxygen rich air over the flames creating a more intense fire and heat.
The majority of the hot air produced in the pellet stove is then directed over the heat exchanger, this is a metallic structure that naturally conducts the heat. A blower or fan then also works in combination with the heat exchanger to blow the now warm, clean air out into the living space.
5. Thermostat Control
Many pellet stove components are atomized and powered by motors. This includes the auger, convection fan, ignition, and blower. As a result pellet stoves are largely automated and typically include a remote control that allows you to alter the thermostat on demand.
The majority of stoves also allow you to control the heat output via buttons found on the rear of the appliance, typically including a low, medium and high setting as standard. Most units also have a reset button that allows you to start the combustion process from the beginning.
Although venting is not strictly a component of the pellet stove itself, it is fundamental to how a pellet stove works. The combustion of wood and pellets produces hot toxic fumes and water vapor that must be safely directed to the exterior of your home.
Like wood stoves, pellet stoves are installed with a vent pipe that usually feeds to the exterior wall of the property or the roof.
As you can now appreciate, pellet stoves are quite sophisticated, especially when compared to wood-burning stoves. For this reason, pellet stove owners can enjoy a superior heating experience, which is safer, more efficient and offers greater convenience.
Although, it’s not all positive as many critics of pellet stoves highlight that more running parts usually means there’s an increased propensity for something to break. In addition, many individuals looking for energy security and off-grid solution do not like the components that rely on electrical power.
Still, for many people, pellet stoves offer a reliable, comfortable and rewarding heating experience that’s difficult to beat.