Ventilation in a greenhouse is not a fad, but a necessity, because the correct temperature regime plays one of the most important roles in the successful cultivation of various crops.
Watering, loosening the soil and timely extermination of weeds are no less important, but the greenhouse effect that occurs when moist air is heated can destroy an unripe crop in a matter of hours. Warm and humid air is an ideal microclimate for the development of most fungal diseases, and also makes it possible for an unlimited amount of pathogenic microflora to develop in the soil.
To avoid these consequences that are detrimental to the crop, timely ventilation of greenhouses is necessary, which will reduce the temperature and humidity of the air inside the structure. Also, when airing, fresh air enters, which is essential for good plant growth.
The easiest way to ventilate greenhouses
The simplest and most inexpensive way is to manually ventilate greenhouses. Each greenhouse structurally has different windows and transoms. By installing a thermometer and a hygrometer in the building, you yourself, based on their readings, will be able to open or cover the transoms, creating natural supply and exhaust ventilation in the greenhouse.
By independently adjusting the number and area of openings, you can quite effectively ventilate the greenhouse, focusing on the direction of the wind and the external air temperature. Like everything, manual ventilation has its advantages and disadvantages. The main advantage of this method is its low cost. You do not need to buy devices, but you can focus on your experience.
Anyone who has grown plants in a greenhouse at least once knows that one has to open and close the windows a dozen times a day. And here you can’t “break away” from this lesson. And there can be no question of leaving.
Using the experience of summer residents and simple devices, you can easily arrange natural ventilation in automatic mode. How good is automation? Yes to everyone: you will not easily create the necessary conditions for the growth of plants, but you will also make sure that the ventilation is carried out depending on the crop that you will grow in the greenhouse. And it is especially pleasant that the system will practically not need to be monitored.
To date, there are four ways to automate the ventilation of greenhouses:
- Using electrical equipment and systems for ventilation.
- By installing hydraulic ventilation automation systems in the greenhouse.
- Mounting bimetallic ventilation systems.
- Integrating automated vents into the design of the greenhouse.
Electrical devices for automatic ventilation
The simplest automatic device for arranging a greenhouse with natural exhaust ventilation is a thermostat with a fan connected to it. The principle of operation of this simple mechanism is as follows: when the temperature rises, the relay is activated and starts the exhaust fan. It will create a small vacuum and suck out heated air from the structure, and fresh air will flow in its place, through natural leaks in the greenhouse structure.
If you provide for the automatic opening of the window at the opposite end of the greenhouse when the fan is turned on, then you can make more efficient ventilation. The fan will drive cool air into the building and lower the temperature and humidity in the greenhouse much faster.
This ventilation design allows you to quite accurately set the parameters for turning on and off the equipment. Having somewhat complicated the design, you can configure the fan so that it creates a certain force of air flow depending on the temperature inside the greenhouse.
But such a simple and effective design is not without drawbacks. First and foremost is the dependence on electricity. The second disadvantage of electrical equipment for ventilation systems is the complex installation of drives for automatically opening or closing ventilation transoms. Many will say that such systems are reliable and when establishing alternative sources of electricity, dependence on a sudden blackout disappears.
They will say — and it will turn out to be right, but solar panels, as an alternative power source, are expensive and have a rather low efficiency, and a wind generator occupies a large area, is expensive and requires wind. Based on the foregoing, such devices cannot be considered as a complete replacement for the electrical network.
Hydraulic ventilation automation systems
This ingenious invention operates on the principle of communicating vessels, one of which is located in the greenhouse and is connected to a system of levers and a transom. The second vessel is installed on the outside of the greenhouse and is connected to the first hose. That’s the whole structure. The system works like this: when the temperature rises, it affects the liquid inside the vessel located in the greenhouse, it expands and opens the window through the system of levers. The container, located on the outside of the structure, compensates for the pressure, slowing down the sharp opening of the window. As the temperature drops, it also affects the liquid and everything happens in the reverse order.
Such automation of ventilation creates effective natural ventilation of the greenhouse, which is sufficient to maintain the desired temperature balance. In addition, the advantage of the system is complete energy independence and the almost complete absence of the need for constant supervision.
But even here it was not without drawbacks, the main of which is the slow opening and closing of the ventilation windows. The fact is that with a sharp increase in temperature, the inertia of the mechanism can play a trick on you, which will lead to overheating of the air and the death of the crop.
How to choose a hydraulic mechanism for arranging ventilation
Paradoxically, despite the rather serious shortcomings of hydraulic ventilation systems, there is an increased demand for them from gardeners. And demand creates supply, so there are a myriad of options for such devices from different manufacturers. What factors to look for when choosing this unit?
- Price category. Efficient hydraulic devices cost a lot. Their price varies from 1.5 thousand rubles. up to 3.5 thousand rubles for one piece. And they are needed for each window.
- Each such unit is designed to lift a window of a certain weight, so before buying the model you like, ask the seller how much it can lift and whether it has enough power to lift the window of your greenhouse.
- The hydraulic lift has a certain mass, so immediately decide how many kilograms your greenhouse structure can withstand.
- Another important factor to be determined before buying this device is whether it can be configured to operate at a certain temperature.
If you immediately determine which device you need before buying, then the efficiency of its work is guaranteed to you.
Each hydraulic opener has a specific opening angle. When buying, pay special attention to this.
Making ventilation with the help of such a device is very simple and not financially expensive. The window opening mechanism consists of a lever and two bimetallic plates, which have different expansion coefficients. In simple terms, it works like this: when the temperature rises, one of the plates bends, and pushing the lever opens the window. When the temperature drops, the plate returns to its original position and the window closes.
Simple, cheap, cheerful, but not without flaws. In such a system, it is difficult to calculate the correspondence of plate buckling to a certain temperature.
Air vents for automatically ventilating the greenhouse
This is a new trend in the arrangement of automatic natural ventilation in greenhouses. The automatic window leaf consists of an oil cylinder and a piston, which acts as a transom pusher. When heated, the oil in the cylinder expands and pushes out the piston, which opens the transom. With “exactly the opposite” everything happens when the temperature drops. Since we know from the physics course that oil cannot be compressed, the pusher piston can lift quite a serious weight.
A wonderful and effective invention, and most importantly — affordable. A simple device to install, it will perfectly replace the somewhat outdated, but effective automatic supply ventilation.
If you’re a fan of growing early fresh vegetables or flowers, then get serious about building a ventilation system in your greenhouse, which is essential for growing most crops.