Any summer resident is not against having a convenient and reliable automatic machine for airing greenhouses.
Throughout the season, this becomes a real problem, because overheating and draft affect the growth of plants and can destroy them. They require fresh air and normal temperature.
Types of structures for ventilation of greenhouses
An electric machine is a fan and a thermal relay that operates at a certain temperature. The device is highly accurate, and its power can be any. One sensor can signal the opening of any number of vents.
Machines of varying complexity exist on the market, but you can also make the unit yourself. The disadvantages are the dependence on the supply of electricity and the cost of it.
The use of a solar battery with a battery allows you to make the ventilation system non-volatile. In addition, a similar energy source can be used for pumping water from the well, recharging the phone and other purposes.
The signal from the sensor can also open the vents for natural ventilation.
Devices based on different values of thermal expansion of materials are simple and reliable, for example, bimetals. The device contains as an actuator a composite metal plate made of metals with different temperature expansion. When heated, it bends, due to which the vent opens. The disadvantage is low power.
The self-made hydraulic system works due to thermal expansion of the fluid, which flows from one container to another and opens the transom with the action of its weight. To create the necessary effort, you need to make a bulky device.
The most common hydraulic systems. They are simple in design and have high power. The principle of action consists in expansion of oil with which the hydraulic cylinder is filled. The fluid presses on the piston, which moves the rod with the transom connected to it through the lever system.
Methods of airing greenhouses
The microclimate for plants in protected ground is maintained as follows:
- Open the vents, transom or door. The best option is to arrange two vents at different heights.
- Through ventilation of a long and narrow greenhouse through 2 doors located at the ends.
- Automated ventilation system for industrial greenhouses with temperature sensors. Some cultures do not like draft. To prevent it, the ventilation frames are placed evenly in the greenhouse at the same height or with air circulation in the upper part.
All devices must be reliable and withstand the effects of wind. To do this, they are made powerful and equipped with special springs and stops.
“Dusya-san” - automatic machine for airing greenhouses: reviews
A simple device with a hydraulic cylinder does not require batteries and electricity.
The automatic machine for airing greenhouses “Dusya-Sun” is installed on the transom, door or window leaf. The principle of operation is to expand when heated fluid that moves the piston of the hydraulic cylinder.
When the temperature in the greenhouse decreases, the liquid decreases in volume, the device returns to its original state, and the vent is closed.
The machine develops not very big efforts. Maximum load on it does not exceed 7 kg. Proper installation and configuration allows you to use the device for many years. Opening operation starts at a temperature of 15 - 25 0 С, and the setting is done manually. When the air in the greenhouse heats up to 30 ° C, the vent opens to the full length of the stem movement - 45 cm. When it cools, it will again be closed by a certain amount, maintaining the set temperature. The small size of the cylinder allows the liquid to quickly warm up or cool. Increasing the temperature in the greenhouse above 50 0 С does not guarantee reliable operation of the device. Strong winds also adversely affect the performance of the machine.
Automatic “Dusya-San” enhanced
Manufacturers have released a reinforced machine for airing the greenhouse “Dusiasan”. It differs as follows:
- wider lever;
- replacement of aluminum threaded connections for cylinder with steel;
- increase the power of the return spring.
Strengthening the design of the machine allows you to increase its resource and ability to withstand a strong wind load. Customer reviews suggest that the design of the machine should be made even more powerful. The maximum load also remained at 7 kg. The body is made of thin aluminum, which is easily bent. The fastening to the window leaf is constantly loosened by the wind, and it must be periodically tightened. Many craftsmen prefer designs of automatic machines for opening greenhouses of their own making.
The automatic machine for airing the greenhouse “Dusya-Sun” is sold unassembled. Aluminum lever system attached to the window and the frame of the greenhouse. Then a cylinder with a holder is screwed into it. The device is installed at the closed window, when the temperature inside the greenhouse does not exceed 15 0 C. The beginning of the opening of the window is regulated by twisting or unscrewing the cylinder.
Consumer reviews on the automatic machine for airing the greenhouse “Dusya-Sun” reinforced note the following advantages:
- Easy installation do it yourself.
- Reliability of work.
- Large amount of stock movement.
Maintenance of the machine consists of periodic lubrication of moving parts with engine oil, control of attachment to the frame and frame and checking the settings.
Do not allow sunlight to enter the hydraulic cylinder. It should operate on the air temperature in the greenhouse, and not on the radiation. For this install screens.
Constructions where hydraulic fluid contains paraffin should not be installed in early spring and late fall. The liquid may solidify at low temperature and the device becomes inoperative.
“Dusya-San” - automatic machine for airing greenhouses - works only during the warm period of the year. After the end of the season it is dismantled until next spring. Before reassembly, the ease of stroke is checked.
How to choose a machine for ventilation of the greenhouse: thermal drive
The thermal actuator is a universal device for opening doors, ceiling and hinged windows of greenhouses. Its basis is a hydraulic cylinder with a piston and fluid inside. When heated, it increases in volume and pushes the piston, which through the system of levers opens the vent.
Domestic construction "Ufopar" creates a force of up to 100 kg and moves the stem to a distance of 45 cm. It contains accumulative and opening cylinders, which makes it quite powerful. For the machine must be provided appropriate support in the greenhouse, so that they can withstand heavy loads. To do this, they often have to be strengthened, since they are designed only to retain a transparent coating, which is polycarbonate. In addition to the pressure from the vents, wind loads are transmitted to the supports. Adjustment to actuation is done with the help of nuts and an adjusting stud.
Air entering the cylinder is a problem for all hydraulic cylinders. It is replaced by motor oil, which is poured through the neck.
Similar specifications have the machine "Tuymazy."
The imported Autovent XL thermal actuator (made in England) provides for lifting frames weighing up to 5.5 kg to a height of up to 30 cm. The design is made of a light alloy, and the cylinder is filled with hydraulic fluid with stable temperature characteristics.
The automatic machine for airing greenhouses “Megavent” of Danish production lifts transoms weighing up to 24 kg to a height of 45 cm. A device of greater power is 2 times more expensive (5 thousand rubles) compared to previous models. It is equipped with a hydraulic shock absorber that protects it from damage in strong winds.
At the choice of model proceed from design features and the area of the greenhouse. The effort to open doors, transoms or vents should not be greater than the specified capacity of the machine. Measurement can be easily performed using a balance sheet by hooking it at the point of contact with the hydraulic cylinder rod.
If the device can not move the transom, then it is necessary to put the automatic machine for airing the greenhouse reinforced.
You can also use 2 models for 1 object. If the vents are small, then opening one will not be enough. It is advisable to install in the greenhouse 1 a machine on an end door or several on the vents located close to the roof.
Self-made automatic ventilation devices
Many make an automatic machine for airing the greenhouse with their own hands on different principles of operation. This is mainly a change in the shape of the device or the volume of a substance.
1. Hydraulic system of two tanks with liquid
Homemade machine for ventilation of greenhouses, where the working fluid is water, works reliably and does not require costs. A metal hermetic tank of larger volume, filled with liquid, communicates with a small can, suspended and connected to the vent through a system of blocks. When heated, the liquid flows from a large capacity to a small one, which communicates with the atmosphere. The weight of the can thus increases and transmits the force to open the vents. When the temperature inside the greenhouse decreases, the liquid flows back into a large container, and the sash closes under its own weight.
The installation of the automatic machine for ventilation of the greenhouse is carried out at a low temperature corresponding to the closing of the greenhouse.
To do this, the weight of the vents must slightly exceed the weight of the small container, which is balanced by the additional load. When the temperature in the greenhouse begins to rise, the fluid heats up and flows into a small container through a flexible hose. That it was visible, it is better to take it from transparent plastic. The weight of the latter increases, and the sash begins to open. In the evening, when the temperature in the greenhouse begins to decrease, the sash should close.
The automatic machine for airing the greenhouse with your own hands can be made from improvised means. But it is rather bulky, and there are no such systems on sale. Low power makes it impossible to work with large transoms. In the greenhouse, you should open at least two vents at different heights to ensure the circulation of fresh air.
2. Automatic with pneumatic actuator
The device works by expanding the air when the temperature rises in a sealed container of large volume. It is placed under the roof of the greenhouse and connected with a flexible hose to a plastisol ball. The latter is placed in a closed space - between the cylinder and the piston. With increasing temperature, the volume of air in the tank increases, and the ball begins to inflate and presses on the piston, which moves the transom sash through the rod and bowstring.
The system is adjusted at a temperature of not more than 15 ° C. To do this, air is pumped into it so that the balloon will slightly inflate. The bowstring is tensioned, but the sash must be in the closed position. As the temperature in the greenhouse rises, the transom should open, and return to its original position as the sun goes down.
The pneumatic actuator is cumbersome, but many use it because of ease of manufacture.
A device is known, where the movement of the vents is made using a bellows, and the system is filled with acetone. It must be airtight and resistant to aggressive media.
Simple and reliable is a machine for airing greenhouses, containing the following tanks:
- Accumulative, filled with air.
- Closing, filled with water, suspended on a cable and transmitting the force of its weight to the rotation of the greenhouse door.
- Opening, suspended above and communicating with the atmosphere.
As a sealed container filled with air, a sewer pipe can be used, closed from the ends of the plugs. In the initial position at low temperature there is no pressure in it. It is communicated with flexible hoses with opening capacity and closing, which holds the door in the closed position.
When the temperature inside the greenhouse rises, the air in the storage tank expands and transfers the pressure to the closing tank, the water from which is displaced into the opening tank. The rotational force of the door is redistributed and it opens. In this case, it is necessary to overcome only the resistance in the hinges of the door, since there is no return spring. When the temperature in the greenhouse decreases, a vacuum appears in the storage tank, which provides for the overflow of water back into the closing tank. In this case, the door of the greenhouse returns to its original position.
3. Airing with valves
The simplest overheating protection device consists of inlet and outlet valves. The principle of operation is based on the difference in temperature inside the greenhouse and outside. A valve of lightweight material is inserted inside a section of a large-diameter pipe. One is installed at the bottom of the greenhouse, and the other at the top, on the opposite side.
The flow of warm air opens the upper valve. Due to the vacuum inside the bottom opens. So that it is not influenced by the wind, a protective shield is installed in front of it. The number of valves may be more.
4. Bimetallic systems
The principle of operation is based on the bending of the metal plate when heated. When cooled, it returns to its original position. However, the magnitude and force of bending are small, and you can only slightly open the window. Often, some designs are described, but their effectiveness is doubtful due to extremely small temperature distortions.
On any homemade machine for airing greenhouses reviews come the most controversial, since its production requires skill. Most of the devices are complex and take up a lot of space in the greenhouse.
The undeniable advantage here is the lack of costs and the ability to repair their own hands. But some designs require considerable investments, for example when using an electric drive.
For closed ground really need a machine for airing greenhouses. It should work constantly, maintaining the microclimate necessary for plants. One overheating may be enough to kill the entire crop.
There are many types of machines that can be made by hand, and they work reliably. The most popular devices with thermo drive of foreign production, but their price remains high. The choice of design depends on the right balance of cost and efficiency.