Greenhouse Heaters
Greenhouse heaters are used to maintain a specific temperature within a greenhouse, to prevent plants dying through unexpected cold weather. Electric space heaters are particularly popular for use in greenhouses, although paraffin heaters can also be used.
Greenhouse Heaters
Greenhouse heating is very ancient, and it is believed that the Romans used water heating in their greenhouses. This may have been done using bronze circulation pipes, and water pipe heating is still used today.
Larger greenhouses still use warm water pipe heating systems to maintain the air temperature inside; however this option is too expensive for most greenhouse owners. The advantage of the warm water piping systems is that they maintain a constant temperature throughout the greenhouse.
Portable Greenhouse Heaters
Smaller greenhouses often use space heaters to maintain the temperature. Portable heaters powered by electricity, gas or paraffin are used. They are able to respond to changes in temperature, and give air circulation around the greenhouse.
Kerosene Heaters
Paraffin or kerosene heaters can be used in greenhouses. It is important to only buy paraffin heaters which were specifically designed for use in the greenhouse. Paraffin emits gases which can be harmful to plants, and heaters designed for greenhouses emit less of these gases. Special types of paraffin can be bought which emit less sulphur dioxide.
Electric Space Heaters
Electric space heaters are popular in greenhouses. They do not emit any gases, and pose less of a fire hazard than a paraffin heater. They usually have a thermostat, allowing the user to set the temperature to the desired level. Some electric space heaters are designed specifically for greenhouses, and have a frost watch setting which increases the temperature if the outside temperature unexpectedly falls.
Electric space heaters with a fan have other advantages in a greenhouse. The constantly moving air created by the heater can reduce dampening in the greenhouse, which can reduce disease in the plants. They are also easy to set up.
Greenhouse Heating
When buying a greenhouse heater it is important to buy heaters that were designed specifically for greenhouses, as household models may not be safe inside a greenhouse. Greenhouse space heaters should be placed where they cannot be easily knocked over, or near flammable objects, to reduce the fire risk. This is particularly the case for paraffin heaters.
Care must be taken when placing a greenhouse heater, especially if they have a fan. Plants which are in close proximity to the fan may lose moisture and be at too high a temperature. If plants are kept on a bench, placing the heater on a floor may be beneficial as the heater will be far enough away.
Polytunnels
Space heaters have also been used in polytunnels. These plastic tunnels are placed over crops to protect them from the elements. They are often used in vegetable plots or allotments. Paraffin heaters and electric heaters can be used in polytunnels. Electric heaters have a fan, which allows the heat to circulate evenly in the polytunnel. Paraffin heaters may be suitable if it is difficult to use an electricity supply.