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Expert grain drying solutions
for Scotland and the North of England

Grain drying systems

Constant humidity and temperature control systems

The Harvest Constant Humidity Controller (CHC) gives you guaranteed drying conditions, 24hrs a day, every day.

Harvest constant humidity controller

The CHC system has a proven record of accuracy, efficiency and economy with thousands of units in use on all combinable crops and onions stores nationwide.

With a range of sizes from 200,000 to 4,000,000 BTU/hr (all using the same plate type burner head, independent burner fan and up to date electronics and controls) they have proved themselves for over 30 years.


Fan performance is critical to the efficiency, low power consumption and low running noise of Harvest Constant Humidity Controller units. The fans are carefully matched to each model in the range to achieve these goals.

Harvest’s own designed and manufactured plate type burner head gives maximum output in a compact design, combined with highly efficient use of available fuel.

Accuracy is everything

The CHC control electronics are mounted in our purpose built housing. Incorporating a large display and simple controls for easy setting of the CHC unit.
The across the range control system modulates 7 stages of heat output to control relative humidity or temperature. Levels of accuracy and performance (as verified by independent testing bodies) ensure efficient controlled drying without the fear of overdrying.

British built to British Standards

All Harvest equipment and components are manufactured to current regulations and each Harvest Constant Humidity Controller unit carries the CE mark. Factory testing of every burner prior to shipping ensures performance and safety from the very start.

High capacity

Onion conditioning and storage has led to the development of Harvest high capacity burners, and these are often assembled in multiples of two or three burners to accommodate the high airflows required.

Harvest CHC units can be supplied on one off with specially designed and built support frames to allow ideal positioning on these oversize installations.

With sensors placed in the main air tunnel, high heat output is possible with both accurarcy and efficiency. This combination gives the majority of UK onion growers the confidence to use Harvest CHC burners for all their drying and conditioning needs.

If you have any questions about the The Harvest Constant Humidity Controller please don't hesitate to contact us.

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