Boiler Fueled by Wood

This article tackles the following topics:

The firewood boiler

Boilers for heating only

Boilers for domestic hot water (separate)

Versatility

A wood boiler produces heat from firewood. The important advantage of wood and wood energy is that it is renewable, abundant, cheap and usable.

Wood burning is now considered the source of energy of the future due to the development of high efficiency wood-fired boilers. Wood is also used by some cogeneration plants to produce electricity and heat. Yields higher than 65% qualify for the Green Flame label and are rewarded with grants and subsidies. Fuel wood is now called "NF firewood" and the heating installers operating on this principle meet professional standards of quality.

Firewood boilers

Wood boilers can be installed only on the ground and have cast iron or steel radiators.

Wood boilers with cast iron heater

Firewood boilers are used primarily for heating. They distribute heat through the central heating system and have a domestic hot water tank. Several innovations have been made in the field of wood boilers in recent years. The most significant would be the replacement of fan-assisted combustion with natural draft, the clear separation of the primary air from the secondary air, the improvements in terms of control (variable speed systems with valves and oxygen sensors), the doubling of the autonomy by the enlargement of the storage compartment and the reduction of radiation losses.

Wood boilers use logs of different types:

Traditional combustion boilers: The wood is introduced and the entire load burns simultaneously. These boilers are controlled by a chain. The yield of these devices ranges between 40 and 60%.

 The investment is lower with these types of boilers. Irregular combustion is difficult to control and there are risks of tarring. The autonomy is low. The establishment of a buffer tank is recommended for the improvement of the device.

Horizontal or inverted combustion boilers: The wood chamber is separated from the combustion chamber. The air supply is optimized and it is regulated by a chain. The yields of these devices range between 50 and 70%. These boilers have an average battery life. The establishment of a buffer tank is recommended for the improvement of the device.

Inverted fan-assisted combustion boilers: The wood chamber is separated from the combustion chamber. The air supply is regulated and optimized through fans. The yields of these devices range between 70 and 85%. These boilers have a controlled combustion and a good battery life. The establishment of a buffer tank is required. The investment is relatively high.

Firewood boilers with hot water accumulation: The use of a buffer tank is particularly interesting with all types of wood boilers. This system improves the operation, performance and lifetime of the device. The heating needs are well below the boiler output throughout much of the year. The boiler operates at suitable parameters thanks to the storage tank. This wood boiler can provide hot water, too. The boiler filling can be reduced to 1-3 loads per day.

Heating boilers

There are specific models designed for heating only. However, the production of domestic hot water can be forced by the addition of a special preparer.

There are firewood heating boilers with cast iron radiators. These boilers have domestic hot water accumulation.

There are also firewood boilers for heating and domestic hot water separately equipped with steel radiators.

Some models can be equipped with an oil or gas burner, which comes into play when the wood supply has been exhausted.