Northern Polytunnels has introduced a new roof fan to help remove excessive heat from polytunnels and polythene clad greenhouses.
Usually used with a temperature switch, the fan can remove 4,600m³/hr (2,700cfm) of air and is supplied with a mesh guard on the inlet. It is installed by cutting out a 30-35cm hole in the polytunnel cover. The fan is then inserted from the inside in a rotating motion, and clipped on to the support bars. Northern Polytunnels says that the seal around the 7.5 kg unit is watertight, even in extreme weather conditions.