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What does a biomass boiler annual service involve?

Posted by Trish O'Flynn on 7 December 2016 at 12:30 pm

Biomass boilers that burn wood logs, chips or pellets, require more attention than gas or oil boilers when it comes to filling, cleaning and fuel delivery. They should also be cleaned and serviced regularly as build-ups of ash and clinker can stop the boiler working efficiently. Some of these tasks you will need to do yourself, such as regular cleaning and checking.

Other tasks, such as servicing, require extra skills. If you can’t DIY, you’ll need to get a qualified engineer. This blog tells you what is involved.

How often should the boiler be serviced?

A well installed and maintained biomass boiler should last for well over 20 years and, while you can service it yourself, manufacturers usually recommend that your boiler is serviced at least once a year by a Microgeneration Certification Scheme (MCS) certified installer. Large installations in constant use may need two services per year.

If you receive the Renewable Heat Incentive the boiler must be maintained in accordance with the manufacturer’s instructions.

How do I know the boiler needs servicing?

Apart from a regular time interval, there are a number of ways to tell that your boiler needs servicing. The boiler may have some or all of these signs, which you will see when cleaning or when the boiler is operating:

  • a lot of unburnt fuel within the ash deposit chamber
  • high levels of soot and clinker within the combustion chamber
  • excessive black smoke production during combustion

Your boiler control panel may also indicate that flue gas temperatures at the exit point of boiler are too high (indicating a build-up of ash is preventing heat exchange within the boiler) or show undue fluctuations in the O2 content of the flue gases (indicating incomplete combustion).

What does the service involve?

YouGen installer member Robinson M&E say a typical service might involve:

  • a general inspection
  • cleaning of airway ports
  • inspection and cleaning of the heat exchanger and combustion chamber
  • all seals and bearings checked, replaced and/or greased where necessary
  • replacement of worn components (such as grates)
  • inspection and testing of all safety equipment
  • inspection of associated fuel equipment
  • flue gas analysis to check combustion efficiency

You will also need to arrange to have the flue or chimney swept and the fuel store cleaned at least once a year.

How long will the service take?

It takes from a couple of hours to half a day to service a biomass boiler.

How much does a biomass boilers service cost?

The cost will vary, depending on the model and use of the boiler, and where you live. A basic service will cost from about £200, while for large installations it may cost up to £500.

Check with your installer whether VAT and parts are included.

How can you minimise biomass boiler problems?

Robinsons M&E find that the most common problem with biomass boilers is a lack of maintenance and burning poor quality fuel. It is a good idea to monitor fuel quality and consumption. Your boiler will operate more efficiently and require less maintenance if you use good quality wood fuel products.

Image credit: SuperHomes


Find a biomass boiler installer

More information about Biomass Boilers and Energy Saving and Renewable Energy on YouGen.

You can find an up to date list of wood fuel equipment and fuel suppliers on our Log Pile database.

About the author: Trish is a web content writer with the National Energy Foundation.

If you have a question about anything in the above blog, please ask it in the comments section below.

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1 comments - read them below or add one

David Brown

David BrownComment left on: 1 February 2017 at 3:50 am

Thanks Trish, this article will help me when I do my next check on my biomass boiler.

David Brown

Team Boiler

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