The benefits of a greenhouse are hardly realized if the temperatures within are not regulated. Greenhouse heaters become handy especially at night or in the cold spells as they help to heat up the structures. Without the heaters, the crops become frosted and may suffer abnormal growth. Available in the market is a wide range of greenhouse heaters for different applications. This exhaustive guide explores the different greenhouse heating devices, their applications, and pricing.
Types of Greenhouse Heaters
Greenhouse heaters are essentially grouped according to the substance used to generate heat, or by the type of heating involved. Convection/space heaters warm the greenhouse space by heating the enclosed air and in effect rising the temperatures of the items therein. On the other hand, radiant or infrared heaters convey heat directly to the objects without relying on the air in between. Conduction heaters are hardly used in orangeries as this would mean crops to come into contact to a hot conductor.
Space heaters are the most common type for hobby greenhouses and the bigger systems as well. They come in different configurations, with or without a circulation fan. Some are inbuilt with temperature controllers while others have to be adjusted manually.
1. Paraffin space heaters – paraffin heaters are some of the oldest innovations still in use today. Their popularity grew because they are greenhouse heaters non electric and require little attention.
These heaters offer various benefits
I. They give out carbon dioxide that promotes crop growth
II. Most models have large reservoirs that run for a whole day without the need to refill
III. They are easy to maintain as paraffin is relatively cheap
IV. They are self-contained and do not call for the need of electric supply
V. Are readily available in various sizes
2. Gas greenhouse heaters — gas heaters are good alternatives to paraffin heaters as their burner only lights when the thermostats tell them to do so. Users have to choose between greenhouse heaters propane and butane, but propane greenhouse heaters suit the application better since butane easily freezes under cold. They also produce the much needed carbon dioxide alongside water vapor that must be vented out. Gardeners with greenhouse heaters gas mains in their facility may opt out of the bottled propane as the former is more convenient.
3. Electric greenhouse heaters — greenhouse operators with electric supply to their conservatories are better placed to use the more efficient electric heaters. Once connected to the mains, an electric current passes through an element that generates heat. A fan strategically placed near the element passes air over it and helps in warming the space.
I. Greenhouse heaters electric are thermostatically controlled, meaning they only deliver heat when necessary.
II. They are portable and applicable in small rooms
III. An electric heater is a non vented greenhouse heater as it does not have harmful emissions
Forced Air Heaters
Forced air greenhouse heaters find wide application in larger structures as they are designed to propel heat across large spaces. They incorporate a duct laid across the length of the structure and a blower to force the hot air through. Forced air heaters are permanently installed and have a low maintenance demand.
Just like electric heaters, infrared heaters are powered by electricity. Most greenhouse operators resolve to these heaters when they want to create warmth to a small zone directly beneath the appliance. Infrared heaters are a good source of warmth to growing crops as well as germinating seeds if installed properly. The best results are achieved if used alongside accessories such as mats.
Tips on How Best to Use Greenhouse Heaters
• To get the best out of your greenhouse heaters, insulate the structure so that the heat does not escape. However, you should install a vent to prevent accumulation of harmful gases if you are using a fuel-type of heater.
• Installing a ceiling fan for your greenhouse helps to improve heat circulation, effectively utilizing the heater output. The law of convection demands that the heated air rises up while the heavier cooler air moves to the bottom, so the fan should force the hot air downwards. A fan with reversible motor provides the best value for money as it supplies heat during winter but vents out air during summer.
• Electric greenhouse heaters perform best if used alongside automating accessories such as thermostats, thermometers, and programmable controllers. This helps to regulate the on/off switching of the device. Digital controllers are the most effective as they closely monitor all the variables and need minimal user input. While analogue temperature controllers are still in use, they are less accurate and efficient than their digital counterparts.
• Take extra caution not to cause short circuits when running extension cables to your greenhouse. Considering the high amount of moisture in the greenhouse, ensure all connections are snug and well terminated.
• For convectional heaters, installing vent tubing improves heater efficiency while cutting down on installation cost. Vents are sheet tubes that run along the length of the greenhouse and emit hot air through pre-drilled holes. An alternative would be to use metallic tubes but at a higher cost.
• Use heated propagation to hasten the germinating process. Heated propagation mats help to keep the sapling warm after germination, as well as heating the benches and roofing cuttings.
• A high number of operators still use open flames such as wood heaters for their greenhouses. Care should be taken not to use such appliances in plastic-covered structure as they may melt.
• Electric fan heaters are best placed at a spot central or on one end of the greenhouse where it is less likely to come into contact with water. The airflow of the fan should be directed away from young foliage but above stronger plants if possible.
• Use horticultural-grade fleece during extra cold nights to insulate the heat and extend the advantages of the heater to plants in greenhouse border soil. Always remove this cloche during the day for the crops to receive adequate ventilation and light.
• In the case of large greenhouses, economize by only heating the areas in dire need of heat. Perspex and bubble wrap insulation are a good means for partitioning greenhouses to achieve economical heating.
Greenhouse Heater Pricing
Greenhouse prices vary according to size and how complex they are. For the greenhouse heaters non electric category, paraffin heaters are the cheapest. On the other hand, electric greenhouse heaters are fairly priced especially those without complex control circuitry. Portable heaters are usually cheap owing to their small size, while infrared heaters rate higher on the pricing ladder. Additionally, a vented heater is more expensive than non vented greenhouse heater due to the extra accessories involved. On average, greenhouse heaters range between $60 to over $1,000 for units with high BTU ratings.