Powercorn 30-75kW Biomass Boiler

The Guntamatic Powercorn biomass boiler burns grain or miscanthus.

Guntamatic: The Powercorn Range

Powercorn boilers have outputs from 30-300kW (up to 75kW from a single unit). We often use a cascade approach, installing two or more boilers in the same system to achieve outputs up to 300kW. This kind of flexibility allows us to install the most efficient system in modulation.

This range is, where necessary, MCS accredited and all models are RHI compliant.

Seriously Low Emissions

The Powercorn's emissions have been measured as significantly below the maximum emissions set out as a requirment for the RHI. The values of each model are in the table below and you can see the certificate here.

Boiler PM NOx

Maximum Emissions

30 g/GJ 150 g/GJ
Guntamatic Powercorn 75 Emissions 11 99


Guntamatic’s Powercorn boilers are famed for their ability to maintain 96% efficiency between 26-100% of output. So you’ll enjoy maximum value for money through a more complete burn.

Burn Wood Pellets, Grain or Miscanthus

The Powercorn can burn ENPlus A1 or A2 wood pellets. Where specified, then Powercorn is designed with a stainless steel liner, meaning it’s happy to deal with the acidic nature of Grain or Miscanthus.

You can store your fuel in a variety of ways from converted buildings to shipping containers. Your fuel can be blown in automatically for total convenience.

Fully Automated

These boilers are designed for a quick and easy start with automatic hot air ignition and a lambda probe to add just the right amount of oxygen. The result is optimum combustion and optimum efficiency.


The Powercorn features Guntamatic’s innovative self-cleaning system, where turbulators move constantly to keep heat exchanger tubes from buildup of deposits.

Control Panel

Your Powercorn boiler comes with a touch screen panel fitted as standard which allows you to quickly and easily change between fuel types.

This puts you in control and gives access to efficiency, fault and maintenance information. Plus, if you opt for the additional GSM module, you’ll be able to control the boiler’s settings from your smartphone.

Low Ash Content

For the volume of fuel, just 0.5-1% ash is generated, meaning that you’ll only need to empty the vast ash bin every six to eight weeks.

Flexible Fuel Delivery

The Powercorn comes with the option of fitting a Flex fuel delivery system. This consists of a vacuum hose which connects your biomass boiler to a custom-built fuel store (of any size) and feeds pellets into your boiler via an auger.     

​When planning your fuel store, evaluate your likely usage so that you can build a store that’s big enough. Ideally, you shouldn’t need to refill it more than three or four times a year.

The outfeed auger is available in a variety of lengths of up to 5.4m to fit a variety custom-built fuel stores:

Flex Size Auger Length Options
Flex 1 1,080 – 1,559mm
Flex 1.5 1,560 – 2,039mm
Flex 2 2,040 - 2,519mm
Flex 2.5 2,520 -2,999mm
Flex 3 3,000 – 3,479mm
Flex 3.5 3,480 – 3,959mm
Flex 4 3,960 – 4,439mm
Flex 4.5 4.440 – 4.919mm
Flex 5 4.920 – 5.399mm

Prefabricated ‘Box’ Fuel Store

We also offer a prefabricated fuel store solution that’s suitable for up to 9 tonnes of ENPlus A1 and A2 wood pellets. The storage box arrives flat-packed, has a stable, steel base, filling tubes and a suction coupling and it’s adjustable in height. Also supplied is a vacuum tube for feeding the pellets into the boiler.

The Box system comes in five sizes:

Box Model Dimensions Fuel Capacity

Box 5.2

170 (w) x 170 (l) mm 2 - 3.4 tonnes 3 - 5.2m3
Box 7.5 210 (w) x 210 (l) mm 3 - 4.7 tonnes 5 - 7.5m3

Box 8.3

290 (w) x 170 (l) mm 4 - 5.4 tonnes 6.1 - 8.3m3

Box 11

250 (w) x 250 (l) mm 5 - 6.7 tonnes 8.3 - 11m3

Box 14

290 (w) x 290 (l) mm 6.5 - 9.1 tonnes 6.5 - 14.1m3

System Dimensions

50 Years’ Experience Built In

Having recently hit their 50-year anniversary, it’s clear that Guntamatic are market leaders in renewable energy technology. This level of experience means that every boiler they make is created with huge industry expertise, and the Powercorn is no exception.

Parts Available for 20 Years

Guntamatic are unique amongst biomass boiler manufacturers as they make all of their own structural components. Every single part of the Powercorn is of the highest standards, offering you maximum return on your investment, low maintenance requirements and a long service life. You can get hold of spare parts easily as Guntamatic guarantee to make parts available for 20 years.

European Training Academy

They put an equal amount of effort into developing installers at their European Training Academy, so an authorised, highly trained and experienced engineer will fit the system for you.

We're Here to Help

make an appointment to find out more

Powercorn Technical Data 30 50 75
Wood Pellets ENPlus A1 or A2 6mm
Grain To ONORM M7139
Miscanthus Chopped, below 25% moisture
Boiler Performance (kW)      
Wood Pellets 7-30 12-50 22-75
Grain 7-25 12-25 21-70 (with additive)
Miscanthus 7-25 12-25 21-70 (with additive)
Draught Requirement (mBar) 0.15 0.15 0.15
Boiler Temperature (oC) 60-80 (70 Grain) 60-80 (70 Grain) 60-80 (70-80 Grain)
Return Flow Temperature (oC) >40 (55 Grain)

>40 (55 Grain)

>40 (55 Grain)


Elevation of Return Flow Pump (RA60 When Buffered)

Pump (Return Temperature Boost When Buffered)

Water Contents (Ltrs) 128 147 256
Operating Pressure (Bar) Max. 3
Ash Storage Volume (Grate) Ltrs 60 60 80
Ash Storage Volume (Heat Exchanger) Ltrs 12 12 12
Width (mm) 1,574 1,574 1,875
Depth (mm) 950 950 980
Height (mm) 1,670 1,670 1,845
Flue Connection Dia (mm) 150 150 180
Weight, No Feed Auger (kg) 550 585 865
Feed Auger (kg) 75 75 75
Safety Heat Exchanger Yes
Power Supply 400V 16A


General FAQs

Can you install abroad?

At the moment, we only install boilers in the UK. We specialise in installations within the Wye Valley.

Can Biomass be burnt in a smoke controlled area?

Approved biomass fuel can be burnt in a smokeless zone, check here to see if your project is located within one,

What is the annual maintenance cost of a biomass boiler?

Annual services of our boilers start at £440 (plus VAT).

How controllable are the boilers? Are they still efficient when ticking over?

You can control your boiler to 1°C and it’ll run at full efficiency (96%) even when it’s operating at 26% of its capacity. This results in a high turn-down ratio and biomass boilers can also be ‘cascaded’ within small district heating schemes and in larger buildings such as hospitals.

Are the boilers fully automatically controlled?

Yes, they are. Your boiler has a touch-screen control panel that allows you to regulate temperature, automatic running and fuel.

What is so unique about the biomass boilers you supply?

The ranges of boilers that we supply offer fantastic efficiencies (up to 96%), reduce CO2 emissions by up to 96% and can save you between 50-80% on your current fossil fuel bills. We only supply the highest quality boilers to guarantee you the best performance for your investment.

What type of flue is required for the boilers?

Our boilers require a twin-wall, stainless steel system.

What is the lead time between placing the order to receiving my boiler?

After you have paid your deposit, the lead time is four to six weeks.

Could the boiler be fitted by our own plumber?

Indeed, but we do recommend using our services so that you can be sure all safety checks have been performed and that the boiler is set up to your specific requirements. You’ll also benefit from full training on how to look after your boiler, something our existing customers have really appreciated.

Do I need a special power supply?

Most of our boilers require a 16amp power supply but some need a 13amp. To find out more about individual boilers, please feel free to contact us. We can supply you with circuit breakers and triple-phase adaptors.

Please could you send information on any grants that are available?

We have covered the Renewable Heat Incentive here so have a read and let us know if you have any questions.

What warranty do you offer?

Our service comes with two years’ onsite warranty.

Can you burn shavings used for horse bedding?

Because of the high levels of ammonia, we don’t recommend burning this as a biofuel.

Can you burn Plastic?

Absolutely not, sorry!

What are the benefits of using biomass as a sustainable fuel?

Available widely throughout the UK, biomass is a low carbon fuel that’s renewable and brings fantastic environmental and social benefits. If managed correctly, biomass is sustainable and can significantly reduce net carbon emissions compared to fossil fuels.

The benefits of biomass are vast:

  • Biomass is carbon-lean meaning it produces a fraction of the carbon emissions of fossil fuels. You can find out more here.
  • Biomass can be sourced locally across the UK, on an indefinite basis. This contributes to the security of supply.
  • UK-sourced biomass can provide opportunity and support the rural economy.
  • Establishing local networks of production and usage minimises the financial and environmental costs of transport.There is no area within the UK that can’t produce biomass.
  • Using biomass fuel provides a firm economic incentive for managing woodland which in turn improves biodiversity. To read more, click here.
  • Many biomass fuels produce lower levels of atmospheric pollutants like sulphur dioxide, which contributes to acid rain.
  • Biomass residues, co-products and waste that aren’t used for energy (or any other purpose) will usually rot. This will generate CO2 in any case, and could produce methane (CH4), a greenhouse gas which is 21 times more potent than CO2.

Wood Pellets

What are wood pellets?

Wood pellets are made from compacted sawdust or any other waste produced from sawmills and other manufacturers.

What is the calorific value of wood pellets?

It’s 4.8kWh per kg, meaning you only need one third of the storage space that you would need for chips. Plus you get three times as much heat.

  • Wood Chips = 250KG/m3
  • Wood Pellets = 650KG/m3
How much do I need, compared to oil?

1 litre of oil is equivalent to 2kg of wood pellets.

What is the cost of wood pellets?

You can expect to pay between £180 - £220 per tonne.

Where is the nearest supplier of wood pellets?

We always recommend using the fantastic Biomass Suppliers’ List (BSL) for a comprehensive list of high quality suppliers across the UK.

Can I use any kind of pellets?

The pellets will need to be ENPlus A1 or A2. These are 10-12mm long and 6mm in diameter. Your wood pellets need to be dry, clean, mechanically robust and possess an ash content defined by appropriate standards. They need to be able to flow freely and delivered via a pneumatic system. Check out this handbook from HETAS for more information about wood pellets.

Wood Chips

What are wood chips?

Passing small logs or wood waste through a chipping machine produces 3mm pieces (also known as G30). Find out more here.

What is the calorific value of wood chips?

Approximately 3.5 kWh per kg, depending on the moisture content of the chips. We recommend a maximum of 30% moisture and you can check this with a moisture meter.

How much space do I need to store them?

Wood chips need approximately three times as much storage space as wood pellets;

  • Wood Chips = 250KG/m3
  • Wood Pellets = 650KG/m3
Where is the nearest supplier of wood chips?

We always recommend using the fantastic Biomass Suppliers’ List (BSL) for a comprehensive list of high quality suppliers across the UK.

What is the cost wood chips?

If you get bought-in wood chips, you can expect to pay £120 per tonne. Alternatively, if you have your own wood supply, you can arrange for contract chipping for around £50 a time. Contract chippers charge about £150 per hour and they can chip around 15 tonnes in an hour. So you can potentially chip your entire annual supply in half a day and load it straight into your fuel store.


What is miscanthus?

Also known as ‘elephant grass’, Miscanthus is a perennial grass which grows and spreads quickly, even on land of poor quality. It’s so easy to cultivate and requires little to no intervention. This is why it’s such a popular option for biofuel.

What is the calorific value of miscanthus?

Miscanthus has a calorific value of 3.6-4 kWh per kilogram and weighs 70-90 kilograms per metre cubed. It’s less dense than grain and therefore you’ll need more storage space.

Which boilers will burn miscanthus?

The Guntamatic Powercorn and Powerchip models will both burn Miscanthus (in chopped or pelleted form). To ask about other models, please get in touch.

What moisture content should miscanthus be in order for it to burn?

It’s imperative that Miscanthus is kept dry and ventilated to get the best out of it. Its moisture content cannot be above 20% and it must conform to W20 standards for chopped, air-dried Miscanthus and W30 for storing and drying.

We advise adding around 0.3 – 0.5% by weight of slaked lime (calcium hydroxide Ca(OH)2) to your fuel before using it in boilers with ratings up to 50 kW and 0.5 – 0.8% for boilers with ratings over 50 kW. This increases the calcium content of your fuel and raises the ash fusion point. This reduces the amount of clinker that can form.