Woodchip boilers tend to be suitable for commercial and large domestic applications, particularly where space is not constrained. The woodchips themselves are just chopped up bits of wood, generally around the size of a finger. It is a simple fuel, but slightly awkward to handle as it does not ‘flow’ in the same way that wood pellets do. It also has lower energy density so fuel stores either need to be larger or deliveries more frequent than a comparable wood pellet installation.

Benefits of Woodchip Boilers

Woodchips tend to be the cheapest biomass fuel that is commercially available (‘free’ logs are cheaper, but at commercial scale are hard to come by!) and it is easy for those with space to use their own timber to make fuel thus further improving the economics. They are fully automatic so, provided there is fuel in the store, can be left to run on their own without intervention. Most woodchip boilers can also be converted fairly easily to run on pellets (whereas dedicated pellet boilers cannot be converted to run on woodchips). Woodchips, along with logs, have the lowest carbon footprint of the standard biomass fuels at around 25kg CO2/MWh (compared with heating oil of around 350kg CO2/MWh).

Our designers evaluate individual situations before advising you on: woodchip specifications, sourcing woodchip and handling and receiving woodchip.

Drawbacks of Woodchip Boilers

Since woodchips do not ‘flow’ in the same way that pellets do, the fuel store needs to be adjacent to the boiler with fuel feed into the boiler by means of an agitator and auger system. This does constrain the system layout. Also, due to the relatively low energy density of the fuel, the store either needs to be larger or deliveries need to be more frequent than for an equivalent pellet installation. Where space and equipment are available, many woodchip boiler operators opt to have a ‘bulk’ store nearby and transfer woodchips to the boiler store by means of a tractor with a loading bucket or similar.

Types of Fuel Deliveries

Many users of woodchip boilers produce their own chips either from their own logs or by buying bulk loads of timber. Once the timber has seasoned, they hire a chipper to process it into chips and store it in a bulk store from where they transfer it to their boiler by means of a tractor with a loader bucket. For those that don’t have space or inclination to operate in this way, there are a wide variety of delivery options although, since it is a relatively low value and bulky product, supply tends to be a local affair. Deliveries can be made in everything from a walking floor articulated lorry delivering loads of around 90m³ at a time to dumpy bags of 1m³ but include agricultural trailers, high lift trailers and blown deliveries.

Woodchip Boilers are Suited For:

Domestic and commercial applications where fuel costs are particularly important and either space and equipment are available for chip handling or a local woodchip supplier is available who can keep the fuel store topped up.