Electric Heating Systems
The most common way to heat a small glasshouse with low target temperatures is using electricity. Harrier GD offers two main types: Circulating Fan Heaters and Electric Tubular Heaters.
1) Circulating Fan Heaters
This is the least expensive way of purchasing heat for your glasshouse. If the structure is small (up to 15m2) and you don’t want to maintain a high temperature, one or two fan heaters could be the answer. They have the added advantage that the heating element can be turned off in the summer and they can be used as a circulating fan.
- Each unit provides up to 2.8kw of thermostatically controlled heat output.
- The fan heater is supplied in dark green as standard.
- Installation only requires an exterior rated socket – so very easy!
- The cost of each unit is £280 + VAT
2) Electric Tubular Heaters
As the glasshouse gets bigger (15 – 30 m2) or the temperature lift increases and demands heat inputs of 6 – 8kw, the more important it is that consideration is given to the way the heat is put into the glasshouse. Electrical Tubular Heaters produce slow convected heat which will be the better option for uniform heat distribution, and will avoid dehydration of plants, which can be caused by fast moving air from fan heaters. They are easierand cheaper to install than a typical Hot Water System, but are less economical to run in a larger greenhouse.
- Each unit is approx 1.0m long with an output of 1kw per unit – making them a compact solution for glasshouse heating.
- They are made from finned galvanised steel pipe, which is robust and is rated to IP65, meaning they can be can be kicked, covered in soil and water and will keep running regardless!
- Placement of the heaters is important from both an aesthetical and functional point of view. Obviously if you have all the heaters at one end, then that end of the glasshouse will be hotter than the end with none! Also, it is worth bearing in mind that a wall is much more insulating than glass, so if you have a lean to for example, then more heaters should be placed at the front than at the back of the greenhouse.
- They can be positioned in a heating duct under cast iron grates, or on the internal wall of a glasshouse, and even under a bench.
- They can be installed either individually or stacked on top of each other.
- How many to install is of high importance to ensure your plants are kept at the right temperature, whilst minimising installation and running costs. In order to achieve this you need to establish the temperature lift required – see details of Temperature Lift in ‘What Temperature?’ section.
- Contact us with details of your glasshouse and our heating engineer will calculate the number required.
A Thermostat is required to set the desired temperature. Harrier GD uses a high quality weatherproof thermostat with an IP56 rating.
For installations using a larger number of Tubular Heaters, and /or when vent mechanisms are electrically controlled, we would recommend upgrading to an HH2 or HH3 Controller. Details of these can be found in ‘Hot Water Heating Systems’
A Contactor Box (Heavy duty switch) should be ordered with heaters. It is connected to the control system, and has the capacity to run high power requirements of multiple tubular heater installations
All projects will be slightly different, so the following is only a guide. If a customer required 4kw of heat they would need:
- 4 x Tubular Heaters
- 1 x Thermostat
- 1 x 4kw Contactor
‘Supply Only’ cost for the above, including delivery would be £1770 + VAT (Nov 2013)
Customers should contact us to establish how many Tubular Heaters they need for the desired temperature lift in their glasshouse. The Tubular Heaters can be sold as ‘Supply Only’ or can be ‘Installed’ by a Harrier GD fitter.