HEATİNG FOR GREENHOUSES - SERALARIN ISITILMASI, SICAKLIGI

Cold House vs. Heated Greenhouse

A cold house is the simplest of greenhouses, it is not equipped with any artificial means of heat and thus the growing season is shortened when the outside temperature drops below freezing. It is not possible to grow frost sensitive plants between late fall and the middle of spring unless you provide heat (which would not make it a cold house!). A cold house does extend the growing season from that of the outdoors by trapping the heat from the sun during the day. And it provides a cozy respite for you to work away from the elements of wind and rain; it also protects plants from these same elements too. When you install a heater into your cold house it becomes a true greenhouse and it transforms the hobby of gardening into a year-round hobby. The minimum temperature required to grow greenhouse plants through the winter is 45° F (7.2°C), so be sure to allow for this extra cost for heating to be included in your monthly budget. Also, be sure that when you begin planning for your greenhouse construction that you build it as near as possible to your house as this will reduce costs for digging and installation of electrical wires (and plumbing if you need that too). It is also better for quick access during the winter months if you have your greenhouse closer to your house.

Gas Greenhouse Heaters

1. All Two Wests' gas heaters have been designed for safe and efficient operation in moist greenhouse environments. Your plants not only benefit from heat but also from growth enhancing CO2 which they generate at the same time.
2. Propane Gas Heaters are easy to install running off bottled gas. Supplied without fittings simply purchase what you require from our high quality range.
3. Natural Gas Heaters provide continuous reliable heat running off a supply of natural gas. These heaters should be installed by a corgi registered fitter.

N.B. these heaters are not flued outside and should only be used in well ventilated greenhouses.

Electric Fan Heaters the easiest way to provide heat

Raise the temperature easily and efficiently, with heaters specially designed for safe operation in a greenhouse environment.

1. ready to use simply plug straight to your mains electric
2. evenly distributes, internal fans circulate the heated air
3. reduces damping off and disease by constantly moving the greenhouse air.

Blue Flame Paraffin Heaters - efficient heaters with variable output

It"s easy to vary heat output and reduce fuel consumption by adjusting the circular wicks of these heaters. Neatly designed with in-built drip trays and a convenient carrying handle.

Parasene Paraffin Heaters - heats greenhouses in any location

These paraffin heaters safely and efficiently heat your greenhouse and at the same time generates CO2, a main plant food for healthy growth.

N.B. Designed for use in greenhouses do not use in domestic situations.

Greenhouse Heating Requirements

Heating is a major concern to commercial greenhouse producers. This is due primarily to the costs involved in the purchase and operation of heating equipment as well as the potentially disastrous effects of a poorly designed system. Although solar energy represents a significant factor in greenhouse heating, supplemental systems are a necessity for year round production.

Sources and Methods of Distributing Heat

Coal, oil and gas are the most common forms of energy used for greenhouse heating. The choice of which of these to use is based primarily on economics. In Texas gas is the most readily available, as well as economical.

Gas burns efficiently, but all forms must be vented to avoid toxic fumes. Many types of gas heaters have been designed for use in greenhouses and they too effect efficiency. When selecting this type of heating equipment it is important to consider fuel and cost factors.

Heat from gas units may be distributed in several different ways. Perhaps the most common method used is through polyethylene (PE) vent tubes. These PE tubes are generally attached near the heater and are inflated when the blower fan is turned on. The heat is forced through the tube and distributed into the house from holes perforated in the PE. These systems may also be used in combination with ventilation and circulation equipment.

The arrangement of PE tubes in the greenhouse greatly influences efficiency as well as plant growth. When tubes are hung overhead, heat is more likely to move out of the "plant zone" and into the upper portion of the structure. When tubes are placed under the benches efficiency is improved and heat is maintained in the appropriate area for optimum plant growth. This type of tube arrangement requires floor mount heating systems or ducts that move the heat from overhead units to the under bench tubes.

Although boilers and traditional hot water/steam heating systems are not used extensively in this area, there is a variation of these systems that is becoming increasingly popular among Texas growers. The use of hot water for "under pot heating" has been proven to be extremely effective and efficient. In these systems, water is heated in a modified hot water heater and pumped through an extensive tubing system that is mounted to the bench. The heat is radiated from the tubes and absorbed by the pots that are placed directly on them. The media in the pot is maintained at a constant temperature which allows air temperatures to be held much lower than with traditional systems. The overall effect is improved plant growth and reduced energy costs.

Thermostats and Controls

There are several types of thermostats and environmental controllers that are available for commercial greenhouseproduction. Regardless of how sophisticated this equipment is, there are some very basic factors that must be considered if the system is to operate properly.

Sensing devices should be placed at plant level in the greenhouse. Thermostats hung at eye level are easy to read but do not provide the necessary input for optimum environmental control. It is also important to have an appropriate number of sensors throughout the production area. Often times environmental conditions can vary significantly within a small distance.

Do not place thermostats in the direct rays of the sun. This will obviously result in poor readings. Mount thermostat so that they face North or in a protected location. It is also sometimes necessary to use a small fan to pull air over the thermostat to get appropriate values.

Calculating Greenhouse Heating Requirements

The key to efficiently heating a greenhouse is matching the equipment to the types of crops to be produced. The first step in this process is to determine the heat loss of the greenhouse. Based on this information the type and capacity of a system may be selected. The following is a series of formulas which may be used for these calculations.