Air temperature is the most important factor in the glasshouse environment as it has a major effect on plant growth, yield and quality. In the UK for the majority of the year, ambient temperatures will fall below that required by most crops and consequently glasshouse heating will be required.

Equipment for green house heating is subjected to a very harsh environment, being exposed to high humidity, watering and corrosive chemical sprays. It is important that green house heaters are designed to cope with the green house environment.

Activair electrical fan heaters have been successfully utilized in commercial glasshouses and polytunnels for over 40 years providing:

• Frost protection in larger glasshouses and polytunnels

• Heating in medium size green houses

• Back up heating - providing extra heating capacity or emergency heating to large gas or oil fired heaters

Care should be taken siting the heaters to ensure that efficient air mixing takes place and hot air is not directed onto the plants. Activair polythene ducting is widely used to ensure uniform air distribution of the warm air and elimination of temperature gradients which adversely affect crop growth and increase heating costs. The ducts can be suspended overhead, run under benching or laid between rows of plants.

An additional benefit of using fan heaters in warm weather, is that the fan can be run without heat to provide air movement for workers and plants.