We want to install a community woodfuel stove or boiler

News flash: Government is giving £2000 vouchers to households that install woodfuel boilers.  To be eligible, the home must not be on mains gas, it must be well insulated, and the new boiler must be operational by 31 March 2014.  This is an excellent and one-off opportunity, similar to the early high feed-in tariffs for photovoltaics.  Click here for more information. 

Do you live in Oxfordshire and own a woodfuel boiler? – log batch, pellet, chip or wood stove with back boiler?  If so, please fill in our survey at at http://www.surveymonkey.com/s/9SZBD9TClick here for the results so far: hopefully they will help others to decide on the purchase of their own boiler.  Thank you.

 

Wood pellet boiler (and proud friend) at Stadhampton primary school

A wood burning stove or boiler is much more efficient than an open fireplace.  Burning wood in an open fireplace typically wastes more than 90% of the heat.  It may even add to your fuel bill if the draft from the fire pulls in a lot of cold air from outside.  Burning wood in a stove or boiler, instead, uses about 80% of the heat.  A stove provides direct heat for the room it is in.  A boiler heats water and pumps it through pipes to several rooms or several buildings (‘district heating’).

Wood burning stoves/boilers take a long time to get going, and so are unsuitable for venues that are used only sporadically or for only a few hours per day.  However community buildings like schools, hospitals and shops that are in use for many hours per day can benefit from a wood boiler.

Switching to a woodfuel boiler will be particularly attractive for community groups whose boilers are nearing the end of their lives, and who would anyway have to pay for a new boiler.  Wood is also particularly good value compared to heating oil: English Wood Fuels provides a useful cost comparison between different fuels.

If you decide to get a woodfuel stove/boiler, you will need to check if you are in smoke control area, get the size right, think about what type of fuel you want, and talk to an expert.

Checking if you are located in a smoke control area.  In smoke control areas, it is an offence to emit smoke from a chimney of a building, from a furnace or from any fixed boiler.  This means that only certain kinds of fuel can be burned.  Smoke control areas can be found below for

Defra’s smoke control areas website gives useful information on what kinds of stoves and fuels can be used in smoke control areas.

The boiler at the Earth Trust in Little Wittenham burns straw bales and wood

The boiler at the Earth Trust in Little Wittenham burns straw bales and wood

Getting the size right.  If the stove/boiler is too large, it will burn inefficiently.  If it is too small, it will not provide enough heat.  A competent fitter will be able to advise on size.  Under-sizing is probably better than over-sizing.

Choosing the type of fuel.  The choice of fuel depends in part on the amount of heat you need, how much space you have, how much time and energy you have to handle the fuel, and the cost of the stove and fuel.  The Forestry Commission has put together a useful flowchart to help decide what kind of stove or boiler might be best for you.

Wood burning stoves/boilers come in all shapes and sizes, from small stoves that can heat a single small room to large boilers that can heat large buildings or clusters of buildings.  The Forestry Commission leaflet Woodfuel burning systems gives many examples.  Wood stove providers will be able to help you decide on the size and type that you need.

One big choice that you will need to make is whether your system should burn logs, woodchips or wood pellets: 


Logs are easiest to provide locally (say from a community woodland) but require a lot of handling to store and move, and most log-burning stoves require regular stoking.

Wood chips are logs that have been chipped by a fuel grade chipper.  The kind of chippers used by tree surgeons do not produce the consistent length chip that is required, so providing chips from a community woodland may not be possible. Wood chip boilers are typically larger, more expensive, automated systems that work best where heat demand is high and there is plenty of storage space.

Wood pellets are typically made of waste sawdust which is dried and shaped into pellets.  The nearest wood pellet manufacturers are in the Surrey Hills and Andover (Hampshire), so ‘woodfuel miles’ can be an issue.  Wood pellets are more expensive than logs or chips, but provide more energy per volume or weight than Logs are easiest to provide locally (say from a community woodland) but require a lot of handling to store and move, and most log-burning stoves require regular stoking. Pellet boilers are relatively compact, automated and closest to fossil fuels in terms of convenience.   

Cherwell District Council have installed both a wood pellet and a wood chip boiler.  Their experiences are described here.

Wood stove technology is advancing rapidly at the moment.  New technologies include more effective combustion chambers, secondary baffling on top of stoves that stop gases from escaping too fast, tertiary air systems that improve the efficiency of the burn, and automated burn control.

Oxfordshire Fire & Rescue recommends that anyone with a wood burning stove or boiler reads their web-page on chimney and open fire safety.

Case studies of community woodfuel boilers include:

Click here to find out more