Heating is a major concern for 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.
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.
Coal, oil and gas are the most common forms of energy used for greenhouse heating. The
choice of which to use is based primarily on economics. For example, in Texas gas is the most
readily available, as well as economically feasible.
choice of which to use is based primarily on economics. For example, in Texas gas is the most
readily available, as well as economically feasible.
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.
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.
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.
There are several types of thermostats and environmental controllers that are available for commercial greenhouse production.
Regardless of how sophisticated this equipment is, there are some very basic factors that must be considered if the system is to
operate properly.
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.
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.
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.
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.
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.
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High heat loss: 25% of your heat loss is downwards. If you insulated under your slab or soil on the floor, you could save 25 % of
your heating cost.
your heating cost.
The typical ground temperature is 55 degrees Fahrenheit. If you attempt to heat your Greenhouse to 75 degrees, you must first
compensate for this 20 degree difference through either heat or insulation in order to get the desired temperature. Further, your
side walls present the same problem.
A.I.M. sells a fabulous insulation product. Similar to bubble wrap (but significantly stronger), it consists of foil on both sides to
reflect the radiant heat, and can tolerate both water and moisture.
High heat demand: The average greenhouse today is heated by hot air. With this conventional method, you must heat the entire
volume of your space before you get the desired temperature where your plants are located.
compensate for this 20 degree difference through either heat or insulation in order to get the desired temperature. Further, your
side walls present the same problem.
A.I.M. sells a fabulous insulation product. Similar to bubble wrap (but significantly stronger), it consists of foil on both sides to
reflect the radiant heat, and can tolerate both water and moisture.
High heat demand: The average greenhouse today is heated by hot air. With this conventional method, you must heat the entire
volume of your space before you get the desired temperature where your plants are located.
Rich Morris,
Owner of Toadflax Nursery in South Glens Falls, NY
Owner of Toadflax Nursery in South Glens Falls, NY
“With conventional hot air heating, I used to spend
thousands per month, but with the Radiant Roots
bench heating design, I was able to have a payback on
the entire system in less than one year!”
thousands per month, but with the Radiant Roots
bench heating design, I was able to have a payback on
the entire system in less than one year!”
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 is
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 is
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.
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.
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.
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.
Greenhouses have several problems when it involves heating them efficiently:
- High heat loss
- High heat demand
- High-energy cost
A.I.M. can solve all your heating problems. We stock the most complete inventory
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of Radiant Greenhouse heating products on the market today. All of our products are designed for easy, do-it-yourself installation.