Heating

 

Currently, the energy cost is high. Therefore the concept adaptation of suitable heating system is highly important.
In some regions, heating is a costly requirement. Consequently, Netafim has put much effort into optimizing the utilization of the resources used for heating, taking into consideration the following factors:

 

    • Accurate and efficient temperature and humidity control.
    • The heat supply must be suited to the plants’ requirements.
    • The heating system must be suited to the energy sources available in the region.
    • Uniform heat dispersal in all the greenhouses.
During the heating-system design stage, Netafim calculates the required heat supply, and based on this calculation determines the size of the burner, the boiler and the heat dispersal system.
Greenhouse heat requirements are determined by:

 

    • Crop heat requirements,
    • Minimum means temperature in the region,
    • Expected heat loss from the greenhouse.
To estimate heat loss, Netafim takes into account:

 

    • Covering properties.
    • Volume of air exchange.
    • Greenhouse structure and shape.
    • Temperature differences between the exterior and interior of the greenhouse and air exchange.
    • Wind velocity.
Two heating options:

 

    • Heat dispersal by hot water, (steel or aluminum pipes).
    • Heat dispersal by hot air (polyethylene sleeves).
Hot Water Method:
This heating method is partly based on direct radiation, in which parts of the plant receive direct radiation from the heating pipes.
The water temperature is normally controlled by 3- 4-way valves, which control the ratios of hot and cold water.
The system enables the establishment of a continuous temperature regimen, with few fluctuations. Another advantage is that heat dispersal inside the greenhouse is uniform. Control and command are carried out by the central system computer.
Conducting the water in steel pipes is also a convenient method for transporting trolleys over the pipes, thus improving efficiency.
Hot Air Method:
The burner causes combustion in the burning cell. Heat thus produced is ejected and passes over the external walls of the burning cell by radiation and convection.
Cold air passing over the burning cell is sucked into the greenhouse cavity, is heated and is then released through the sleeves into the greenhouse.
The air circulation process is executed by a centrifugal blower operated by electric motor. Heat in the greenhouse is dispersed through a system of perforated sleeves.