Biomass burners have been popping up on farms and estates all over the country during the past decade thanks to some attractive renewable heat incentives that have helped subsidise installation and fuel costs.

The financial sweeteners have also made it viable for landowners to bring neglected woodland back into regular management, selling the hardwood and chipping the less-valuable softwood for heating buildings and grain stores.

However, the biomass market boom, combined with the lack of UK-grown softwood, has seen the price of timber rocket.

See also: Tips to help keep biomass boilers running trouble-free

According to the Forestry Commission, the UK’s biomass consumption is estimated at roughly 22m green tonnes a year, of which we imported about 17m in the form of pellets – with more than 80% coming from Canada and the US.

To avoid imports, many biomass burner owners stockpile vast quantities of timber lengths, either from their own woodlands or in the form of bought-in rounds, ready to be freshly chipped by contractors.

The downside of this approach is that it takes up yard space and it can be difficult to find and pay for huge quantities of timber at once.

One way to reduce the peaks in production is to chip smaller amounts of wood on a regular basis by investing in a machine with an output more in line with the boiler’s intake.

Owning one, either outright or in partnership with a neighbour, could also be useful for processing felled trees and any offcuts from around the farm.

We’ve rounded up a few different options designed to process timber between 400mm and 680mm in diameter, but all the makers featured offer a vast range of bigger chippers.

Heizohack HM8-400K

Fuelwood in Warwickshire has been supplying the German-built Heizohack range since the mid-1990s.

© Fuelwood

It recently introduced the HM8-400K model to fill the gap between the hand-fed chippers costing about £35,000, and the bigger, crane-mounted contractor units at more than £70,000.

The HM8-400K is capable of swallowing wood waste, sawmill offcuts, branches and trunks up to a diameter of 400mm.

It has a low-drag drum and 470kg flywheel that, once up to speed, keeps running with relatively low horsepower input from the tractor.

One of its key features is the use of eight small blades on the drum, which nibble away at the timber rather than taking huge bites to further reduce the power requirement.

Fuelwood says it has seen a number of biomass boiler owners take the chipping job in-house to avoid the infrastructure, material and storage required to keep a chipping contractor busy.

The HM8-400K has a more manageable output of 30-40cu m/hour and the size of chip can be altered by adjusting the feed-in speed or the interchangeable sieves.

These come in 50x50mm for G30 grade chip and 60x80mm for G50.

There is also the option to install a crane on the rear.

Mus-Max Wood Terminator 7 LZ

The Mus-Max range first arrived in the UK in 2008 and now consists of three types of chipper.

© Ben Price

Since 2019, the UK distribution job for the Austrian-built machines has been taken on by B Price Mus-Max Specialist, based in Shropshire.

There are six pto-driven models, led by the Wood Terminator 12, which is designed to churn out 300cu m/hour and demands more than 400hp.

The Wood Terminator 7 LZ is the smallest unit on offer. It is capable of producing 60cu m/hour and is the only model to have the option of hand and crane feed-in.

The 7 LZ is apparently as popular with estates and farms chopping their own wood as it is with arboriculturists making the step-up from a small chipper.

It can produce G30 and G50 chip with screen sizes from 20mm up to 80mm.

A key design feature is that the flywheel is connected to the drum, rather than the blower, to maintain chipping consistency.

The machine is controlled by a cable remote that uses electronic load control to manage the material feed. It also comes with an hour counter.

Pezzolato PTH 700

North Wales-based machinery dealer DA Hughes imports the Italian-made Pezzolato chippers and uses them in its own forestry contracting business.

© DA Hughes

The first customer unit was delivered into the UK in 2014.

The PTH 700 is a mid-sized, tractor-powered model in the 10-strong range, and is capable of swallowing timber up to 500mm in diameter and producing up to 80cu m/hour.

A large 1,250mm fan connected directly to the drum’s shaft can spin slowly – at less than 600rpm – to help reduce dust and improve chip quality.

The drum has three staggered blades that cut twice per revolution, but customers can choose to spec two full-width units.

There is also a choice between standard and “light” blade types.

Screens can be manufactured to meet the specification of chip required – typically G30 and G50 – and an onboard computer varies the feed-in speed to suit the screen fitted.

The chipper is controlled by an LCD screen wired to the tractor or crane cab, but radio remote-control is an option.

It can be ordered with Cranab or Epilson cranes from the factory, or fitted with a customer’s existing unit.

Jenz HEM 593Z

German manufacturer Jenz is well-known in the biomass world for its high-output chippers, and even one of its smallest pto-driven model is still on the large side compared with the others in this round-up.

© Westcon Equipment

Its size and price means farming interest will probably be limited to biomass boiler owners clubbing together to share the cost.

Jenz machines are imported to the UK by Westcon Equipment based in Sturminster Marshall, Dorset.

The HEM 593Z is its most popular model, but the smaller 540Z would be a good choice for farmers with multiple boilers and their own woodlands.

This is being updated next year to become the HEM 360Z.

The 593Z was introduced around 2014 and requires a minimum of 350hp on the front.

Jenz chippers are built to withstand up to 10,000 hours of working life, and the company favours a hydraulic blower setup, which helps to reduce power demand and improve chip quality. 

Output is dependent on tractor power and screen size, which includes G30, G50 and even G100 options, but users should get in the region of 230cu m/hour.