A well designed and well maintained biomass installation should operate effectively for many years. However end users may experience operational problems in terms of higher emissions and increased fuel use that either reduce performance or at worst result in outages.
End users should seek expert help to identify the causes of any problems. A list of common problems with biomass installations is listed below
- Low delta T: if the difference between flow and return temperatures is very low it means poor efficiency, as hot water has been circulated around a system without being used for heating or domestic hot water (DHW).
- Boiler Combustion settings: if fuel is combusted incorrectly it increases clinker formation, ash and emissions and leaves unburnt fuel in refractory and ash augers. If there is clinker in the ash bins it is evidence of problems with the combustion settings and or the fuel specification.
- Boiler to buffer pipework and controls: typically the buffer should control the boiler and set-ups that simply seek to keep a buffer tank full of hot water are not efficient. Such an arrangement is like trying to keep a massive kettle hot when there is no requirement for a cup of tea.
- Flue design: the majority of a boiler’s losses are associated with flue gases and the flue must be designed to operate with the boiler.
- Integration with back up boilers: Controls that determine the lead boiler should maximise the role the biomass plays.
- Inadequate insulation: radiant heat losses in the pipework, buffers and heat exchangers should be controlled by well specified insulation products.
- Pumps set too high: flow rates and temperatures should be set to user needs and avoid unnecessary pumping costs that push high temperature hot water around systems.
- Boiler sizing: oversized boilers are common problem, and result in poor performance. Good advice should be sought to size systems for their heat loads.
- Buffer sizing: buffer tank sizing is important and should be considered at the design stage. They can be too big or too small.
- Cycling demand: the frequent firing on and off reduce performance and creates wear and tear. This can be resolved with good buffer to boiler controls and proper integration with a BMS.
In addition to these factors the fuel that is supplied into the boiler will have a major impact on performance. The key consideration is to ensure a consistent fuel in terms of moisture content and particle size and ensure the boiler is commissioned and set up for that fuel. If the fuel specification is changed the combustion settings will need adjustment. Find out more about fuel moisture content and wood fuel quality standards.