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Expert grain drying solutions
for Scotland and the North of England

Grain drying systems

Harvest tunnels, Challow tunnels and fan rooms for grain drying

Harvest Tunnel

Fabricated from hot rolled steel section, the Harvest main air tunnel frames provide exceptional strength and rigidity. Built to handle not only high storage loads, they can accept the loads created by the action of the Harvest Maxi Stirrer. A galvanized finish throughout ensures a long trouble free life with minimum maintenance.

Harvest tunnel and fan house

Frame centres are set to an extremely economical 1220mm, meaning fewer frames per tunnel. Frames also align with most timber floor designs, and the full length air doors ensure uninterrupted airflow under the drying floor.

The low profile corrugated cladding is manufactured from high tensile pre-galvanized sheet to match the extended service life of the tunnel frames. These corrugations are designed to eliminate crop hang up and minimize dust traps.
Overall this tunnel has proven to be extremely durable over many years of service.

Our installation team can provide fast and efficient erection of all tunnel components ensuring a first class product finish to your grain store. Easy access tunnel doors are available to fit end plates or the load bearing side wall. Heavy duty galvanised steel ladders are purpose designed to fit easily into any store layout.

Specifically designed for use with the Harvest Maxi Stirrer the tunnel is available with storage heights of 2.4m, 3.0m, 3.6m and 4.2m and width of 1219mm or 1524mm. All tunnels are complete with extended side panels above the maximum storage height in order to prevent grain spillage onto the walk way, and angle stirrers track in lieu of the hand rail. Completing the specification are resin bonded holding down bolts and mastic.

The strength of the Harvest main air tunnel makes installation of catenary cable supports simple and the strength of the main frames enables internal fan houses to be mounted directly onto the tunnel. The internal fan house simplifies the design and location of the building and the containment of fans, burners and acoustic inlet cowls enables noise to be reduced to acceptable levels. The design of the fan house means that single of multiple fans either centrifugal or axial can be used with space for humidity of temperature controlled Harvest Burners.

Main air tunnels used with stirring systems and the temperature method of drying can be internally insulated with foam giving a considerable reduction in energy required to give the necessary temperature lift.

Challow Tunnel

Challow main air ducts are of proven strength and stability. The plywood cladding, which forms the flush outer skin, is tongue and groove jointed for strength and provides an airtight seal. The engineer designed and specified Challow duct range has the high performance and specification to complement the Challow drive-on drying floor. Between each hardwood frame is a slide control to optimise the distribution of airflow below the drive-on drying floor.

Challow tunnel

The air duct frames are bracketed to the concrete floor and the sides are extended without cross bracings to provide safe, unobstructed walkways within the air duct and on the catwalk above. The smooth, vertical faces readily accept internal dividing walls.

The air duct can be installed either centrally or, depending on the store width, to one side. A variety of sizes are available to give the correct capacity for efficient air flow through the drying system.


Storage height

Storage width


TC42 2400mm 1024mm 42000 cfm (70,000 m³ /hr)
TC60 3000mm 1244mm 60000 cfm (100,000 m³ /hr)
TC78 3000mm 1524mm 78000 cfm (130,000 m³ /hr)
TC87 3600mm 1524mm 87000 cfm (145,000 m³ /hr)
TC115 4000mm 1824mm 115000 cfm (195,000 m³ /hr)

Internal Fan Rooms

Internal fan rooms provide an alternative to the traditional external fan house, particularly where space is at a premium. Positioning the fans above the main air duct has the advantage of utilising space within the store that is not normally used.

Challow tunnel fan house

Internal fan rooms are suitable for both centrifugal and axial fans, with ample room for the addition of gas burners and bio-mass heat exchangers if required. Further advantages include the ability to introduce acoustic materials within the structure to reduce noise levels, reduce the footprint of the store, and closing off a potential entry route for vermin at ground level.

Contact us if you have any questions about any of these grain drying tunnels and fan rooms.

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