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AM15 Biomass heating (2014) (pdf)
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AM15 Biomass heating (2014) (pdf)

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This Applications Manual concentrates on biomass systems with biomass boiler outputs in the range of 50 kW to 5 MW burning woodchips or wood pellets. The major application areas for biomass boilers will be for heating systems for existing buildings, and those with substantial heating and hot water loads throughout the year. Batch-fed boilers are briefly mentioned but it does not cover hot-air heaters, biomass gasifiers or biomass CHP systems.

The design of biomass boiler systems is considerably more complex than that of oil and gas boiler, heat pump and chp systems, and requires an informed design approach. Integrating biomass boilers with oil and gas boilers with load circuits to form efficient and controllable hydronic systems requires a detailed understanding of the dynamics and subtleties of biomass boilers. Hence, this Applications Manual is designed to help readers understand biomass boiler systems to a level where they can make knowledgeable decisions on system design. With the exception of specific hydronic arrangements for integrating biomass boiler systems with oil or gas boilers in Chapter 7 and specific advice on health and safety requirements, this manual does not provide prescriptive solutions nor does it attempt to cover every eventuality. The primary readership of this manual is intended to be professional building services engineers in the UK.

Low-carbon related legislation and regulations are changing rapidly, and also vary significantly country by country. Reference is made throughout this manual to the UK’s Renewable Heat Incentive (RHI) scheme and guidance is provided on measures which may be required to secure accreditation under the non-domestic RHI. Those installing boilers to provide heat to domestic properties, and seeking support under the domestic RHI, should refer to the appropriate guidance available on the Ofgem RHI website.

Acknowledgement is made to the Carbon Trust for their extensive support to the early draft of this AM under the Biomass Heat Accelerator programme and to the contribution of the initial authors.

Note: AM15 updates and supersedes KS10: Biomass heating 2007 which has now been withdrawn.



1 Introduction and scope

2 Biomass fuels, combustion and emissions

3 Fuel delivery, storage and extraction

4 Biomass boiler types and characteristics

5 Designing with buffer vessels and thermal stores

6 Sizing a biomass boiler and suitability of biomass

7 Connecting biomass boilers in parallel or series

8 Controls, pressurisation and headers

9 Heat metering

10 Flues

11 Summary of key considerations for biomass boilerhouse design



Key to symbols used in schematic diagrams



Principal author: David Palmer

Contributing authors: Colin Ashford, Jim Kinnibrugh & Graham Smith

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