Choosing a biomass boiler

When choosing a biomass boiler, be prepared that it may need more attention in comparison to a regular gas or oil boiler. As with gas and oil-fired boilers, biomass boilers will need an annual safety and maintenance check to qualify for RHI payments. Biomass boilers produce very little ash because they combust fuel very efficiently and cleanly. The ash can be disposed of as low-grade fertiliser in your garden or removed by your fuel supplier when they deliver your fuel.

Biomass boiler maintenance

Depending on the type of wood fuel you will either have to pay it a little bit less or more attention. Wood chip, pellet and logs will create different amounts of waste as they burn differently. Make sure to maintain your biomass boiler according to the manufacturer instructions. In general, however, it is advisable to:


Have a weekly visual inspection of the boiler to make sure it’s running without issues. Keep an eye on ash levels and dispose of it if necessary.


On a monthly basis, we recommend that you check the gate. You should also clean the chamber and remove the excess of ash.


Every quarter clean the lambda probe and flue gas sensor which allow to monitor the oxygen levels.

Half a year

Every 6 months you should check and wipe flue gas return, check the motors and drives and clean heat exchangers and combustion chamber.

Biomass boiler cleaning routine

Best way to start cleaning your boiler is by reviewing the manufacturer instruction. This is because there are many types of boilers on the market from non-self cleaning to automated ones that will tell you exactly when you need to empty the ash bin. Good quality wood fuel will produce less ash, but it still needs to be removed on a regular basis even if it’s only once every year.

Servicing of biomass boiler

To make sure your boiler works well and remains efficient you should maintain it on regular basis.

Typically a boiler should be serviced once a year, but it really depends on the manufacturer’s instructions. It is more appropriate to service the boiler in accordance with the actual operational hours. For example, large biomass boilers for commercial purposes, have a higher number of safety systems, motors, fans and cleaning components. For that reason, they may need to be checked every quarter. The best solution is to put biomass boiler under a maintenance contract and enter a Fuel Supply Agreement such as the one offered by Woodyfuel. This is to ensure that you receive the best quality wood fuel that won’t damage your boiler.

Choosing the right fuel

Biomass boilers are designed to burn different types of biomass. Typically they are specific to wood chip or wood pellet and the variation within these categorisations.

There is a significant difference in performance between well dried and high in moisture content wood chip. Therefore you should always make sure to use the best quality wood chip. It is worth knowing that wood chip is typically cheaper than a wood pellet, but it also displays lower calorific value. This means you will need more pellets to obtain the same amount of energy and as a consequence more storage space or more frequent fuel deliveries.

Fuel monitoring

There are few things you can do to inspect the quality of the fuel as well as automate the process of renewing your wood fuel supplies on regular basis with no effort:

Moisture content

You can check moisture content through touch test. You can also choose a professional method by oven drying or by using a timber conductivity meter.

Particle size

Typically for precise measure, a sieve or sifter needs to be used to determine particle size, but you can also complete a quick visual inspection yourself.


Complete a visual inspection to look for foreign bodies like plastic or stone, or you can complete more accurate tests by sending a sample to a laboratory.

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