During the operation of the greenhouse, one of the most important tasks is to maintain the optimum temperature at the natural humidity level. It is easiest to solve the problem by airing the room.
However, manually doing this is often problematic due to lack of time. Therefore, it makes sense to arrange automatic adjustment of the position of the valves using a thermal drive.
How to make a machine for airing greenhouses with your own hands? How to properly organize automatic ventilation in the greenhouse? How to make a window-pan for a greenhouse from polycarbonate?
The principle of operation of the thermal drive
Regardless of the design of the thermal drive, the essence of his work is to open the window leaf with increasing temperature. When the air in the greenhouse cools down, the thermal actuator automatically closes the vent to its original position.
The main elements in the device are two:
- sensor;
- actuating mechanism.
Wherein design of the sensors and actuators themselves may be completely arbitrary. Additionally, devices can be equipped with closers and locks, ensuring tight closure of the transom.
To their merits include great power and wide possibilities of programming behavior.
Disadvantages - if there is a loss of electricity supply, there is a risk of either venting the plants due to the remaining vents open at night, or to cook them on a hot day with unopened ventilation.
Scope of application
Where can I install a thermal drive for greenhouses with my own hands?
Installation of thermal actuators (photo on the right) can be made absolutely for any greenhouses: film, polycarbonate and glass.
In the latter case, to the choice of drive you need to be especially carefulSince the glass window has a considerable mass and it can take quite a powerful device to work with it.
Besides, the size of the greenhouse matters. It makes little sense to install such a device in a greenhouse with an area of one and a half square meters. There is simply not enough space here, and the frameworks of such structures are often unable to bear the additional burden.
In very large greenhouses, some problems may also arise. This is due to the need to simultaneously open several vents, often also of considerable size. The power of a self-made thermal drive is simply not enough to do such hard work.
Most harmoniously Thermal drives fit into the design of greenhouses made of polycarbonate. The vents made of this material are light enough to be controlled even by an improvised device. At the same time, polycarbonate is reliable enough to make it possible to make a strong window leaf suitable for multiple opening and closing cycles.
Execution options
According to the mechanism of action There are several main groups of thermal actuators. How to arrange automatic opening of the vents in the greenhouse with your own hands?
Electric
As the name suggests, in these devices the actuator is driven electric motor. The command to turn on the motor gives the controller, which focuses on information from the temperature sensor.
To the merits electric drives include high power and the ability to create programmable intelligent systems,including a lot of a variety of sensors and allowing the most correctly determine the mode of ventilation of the greenhouse.
Main disadvantages electrothermal drives - dependence on electricity and not the lowest for a simple gardener cost. In addition, the humid atmosphere of the greenhouse does not contribute to the long-term operation of any electrical appliances.
Bimetallic
The principle of their work is based on different coefficients of thermal expansion for different metals. If two plates of such metals are somehow bonded together, then when heated, one of them in size will necessarily become larger than the other. The resulting bias and is used as a source of mechanical work when opening the vents.
By virtue such a drive is its simplicity and autonomy, a disadvantage - not always enough power.
Pneumatic
Pneumatic thermal actuators based on the supply of heated air from an airtight container to a drive piston. When the container heats up, the expanded air is fed through a tube into the piston, which moves and opens the transom.When the temperature decreases, the air inside the system is compressed and pulls the piston in the opposite direction, closing the window.
With all the simplicity of this design, it is quite difficult to make it yourself. It will be necessary to ensure a serious sealing not only of the container, but also inside the piston. Complicates the task and the property of air is easily compressed, which leads to a loss in the efficiency of the entire system.
Hydraulic.
Hydraulic Thermal Drive Mechanism set in motion by changing the balance in the weight of a pair of tanksbetween which the fluid moves. In turn, the liquid begins to move between the vessels due to the change in air pressure during heating and cooling.
Plus hydraulics is its relatively high power at full power independence. In addition, it is much easier and cheaper to assemble such a structure with your own hands than for other drives.
How to independently organize automatic ventilation of greenhouses (thermal actuator, which one to choose)?
Making your own hands
How to make a device for ventilation of greenhouses with their own hands? For self-made the simplest and most effective option.thermal drive for greenhouses is hydraulic.
At its assembly will need:
- 2 glass jars (3 l and 800 g);
- brass or copper tube with a length of 30 cm and a diameter of 5-7 mm;
- a plastic tube from a medical dropper with a length of 1 m;
- a piece of wood bar length equal to the width of the opening transom. The cross section of the bar is selected based on the weight of the window, because it will be used to make a counterweight;
- hard metal wire;
- sealant;
- two covers for cans: polyethylene and metal;
- nails 100 mm - 2 pcs.
The assembly sequence will be:
- 800 grams are poured into a three-liter jar;
- a jar with a seamer tightly sealed with a metal lid;
- a hole is punched or drilled into the lid into which the brass tube is inserted. It is necessary to lower a tube until 2-3 mm to the bottom;
- the joint of the tube and the cap is sealed with sealant;
- one end of the plastic tube is placed on the metal tube.
Then they work with a can of 800 g, only it is left empty, closed with a plastic cap and a plastic tube is inserted into the second end. From the cut of the tube to the bottom of the bank also leave 2-3 mm
Final stage place banks on jobs. To do this, three-liter with the help of nails and metal wires are hung near the rotating window, so that at any position of the window, the length of the plastic tube is enough.
A small jar is also fixed on a nail and wire and fixed on the upper part of the frame of a horizontally rotating window leaf. In order to balance the mass of the can, a bar-counterweight is nailed to the lower part of its frame on the street side of the window.
Now, if the temperature in the greenhouse rises, the air heated in a large jar will begin to squeeze out the water through a plastic tube into a small jar. As water is drawn into the small jar, due to the increased weight of the upper part of the window, it will start to turn around its axis, that is, it will start to open.
As the air in the greenhouse cools, the air in the three-liter jar will cool and compress. The resulting vacuum will pull the water back out of the small jar. The latter will lose weight and the frame window under the weight of the counterweight drops to the "closed" position.
