John Smith Swarbrick Hall Farm – draperHEAT

The challenge

Early  2016, plans were set in motion to extend the existing 2 house broiler farm with an additional 2 new 50,000 bird houses. The existing two houses are heated by a single 600 kW pellet boiler with centralised 600 KW LPG, both houses within a single boiler room. Whilst the existing pellet boiler meets demand efficiently, there is no spare capacity for additional heat loads to serve new sheds.

So, the challenge was to review the whole energy mix to serve the existing two houses, proposed additional two new and consider future houses or other heat loads on the farm. It was concluded to consider two new plus two future houses all 300 Kw peak /house and possibly pick up some of the heat load from the existing two houses.

draperHEAT’s modelling looked at all scenarios and fuel options, which has many drivers tailored to suit the individual farming business.  CHP modelling looked viable until the tariff changes mid 2016 which unfortunately lead to CHP systems becoming unviable at this capacity.

So, heat only options were modelled, with the various fuels contrasted against each other plus the associated operational, running and maintained costs evaluated.

With the pig side of the farming business being reduced, on farm straw at John’s cost of £28/T became a low-cost fuel option with long term stability being the grower and supplier.

The solution

  • • Justsen Flex 17 – 995 KW automatic straw boilerReka 22m auto fuel feed table with auto straw chopper
  • • Hoval SR1200 Kw diesel fired back up boiler
  • • Turn key boiler room mechanical/electrical installations including load sharing controls
  • • Steel pre-insulated underground heating mains provide low heat loss and long life.
  • • Turn key design, project management, H&S compliance commissioning.
  • • RHI compliance and applications.

draperHEAT drew on many years’ experience in combusting a variety of fuels and have strategic agreements with several boiler manufacturers who offer ’best in class products’ and technical support for the years to come. As with most biomass systems, fuel feed and logistics play an important role in the success of the system as a whole. Straw poses many challenges to go from Heston bale to heat. The solution for John is a Danish Justsen boiler with slow rotating automatic chopper and 22m Heston bale feed system. The system is designed to operate with a variety of straws including rape, wheat & miscanthus. Key to the system is a slow rotating chopper, fully water cooled grate and automatic ash extraction, clinker and ash being the challenges with straw.


The heating system was commissioned Dec 2016, 10 days ahead of chick placement, allowing time to pre-heat and raise the concrete floor temperatures. Initially running on wheat straw, the boiler system is now into the 6th crop and operated on wheat and rape straw with no problem maintaining around 88 deg flow to the sheds. The backup boiler has been automatically enabled on occasion to maintain constant flow to the sheds. Fuel costs for home grown straw are below 1p/kWh so offer good savings against LPG currently around 4p/kWh and pellet around 3.8p/kWh

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