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Orchard Heaters

Each year, approximately 5-15 percent of the world’s crops is damaged by cold temperatures.
Orchard heaters are commonly used in various areas of the world to prevent frost damage to fruit and fruit trees.
The use of heaters of various design, or lighting fires using various combustible materials are one of the oldest frost prevention systems.
There are several advantages to using heaters that alternatives do not provide. Most heaters are designed to burn fuel and can be placed as free-standing units or connected by a pipeline network throughout the crop area. Experience has however shown that a large number of small fires burning throughout the orchard provide better protection than a few large fires concentrated in spots. 
Traditional heaters have been found to be less user-friendly and can lose up to 85 percent of the heat produced due to radiation into the earth and sky (known as the "stack effect").
LPG's high heat content combined with the unique designs of modern heaters ensures that a greater percentage of heat to radiate directly into the crops, thus increasing the efficiency of crop protection.


Generally, the heaters fall into two categories. There are heaters that raise the temperature of metal objects (e.g. stack heaters) and there are those that operate as open fires.
Heaters provide frost protection by direct radiation to the plants around them and by causing convective mixing of air within the inversion layer. 
Protecting with heaters is technically dependable and growers preferred heaters until pollution problems and high costs of fuel relative to the crop value made the method too expensive for many crops. Now heaters are mainly used to supplement other methods during extreme frost events and for high-value crops. 

Most of the energy from heaters is released as hot gases and heated air that mainly warms the ambient air by convection. Radiant energy from the heaters travels directly to nearby plants that are in direct line-of-sight of the heaters. 
There are three types of heaters suitable for use in horticulture.

Direct fired heaters provide economical and efficient frost protection during the cold months, but can also supply fresh unheated air for summertime ventilation. Indirect fired and unit cabinet heaters are capable of increasing the heat by 10-15° without damaging crops.

For frost protection, radiant energy is more efficient than heated air, and the radiation emanates best from a hot, solid surface (e.g., a steel smokestack of a heater). Radiant heaters directly warm a precise location by radiating infrared heat. No heat is wasted nor do they circulate dust, so they are ideal when a clean atmosphere is required. A portion of the combustion is converted to sensible heat as heated air and gasses from the flame. As this heated air rises and mixes within the inversion, it can warm the leaves, fruit, and branches.

All of these heating systems are compatible with LPG, which means you get the added peace of mind of a reliable, clean burning energy supply.

Models like the AgHeat propane heater possesses a pyramid shape which allows more heat to be directed to the air surrounding the crop than vertical pipe designs.

Networks of connected heaters have the advantage of the ability to control the rate of burning and shut all heaters down from a central pumping station simply by adjusting the pump pressure.



LPG provides a clean-burning and efficient option for orchard heating compared to diesel-fuelled heaters. In contrast to diesel spills that pose a significant risk to surrounding orchard trees by contaminating water and soil, LPG vaporizes into the air and is nontoxic and insoluble in water, eliminating any risk of soil or water contamination.

LPG-fueled orchard heaters also offer major operational benefits over diesel-fuelled heaters:

  • Ease of use—LPG gas flow rates are controlled by a single pressure regulator.
  • Reduced ignition time— In standardised tests commissioned by the PERC, it was discovered that LPG burners required one hour compared to two hours for diesel burners, which must have their air-vents adjusted by hand to achieve the proper setting.
  • Reduced shut-off time—Closing the valves to the sub-main supply lines for the LPG burners only took five minutes, while diesel burners required one hour.

Manufacturers (1) and Resources