The temperature regime, which is formed and regulated by several systems at once - heating, ventilation, air humidification, evaporative cooling and others - plays a major role.
For constant monitoring with the possibility of adjustment, an air temperature regulator in the greenhouse is used, which is an important element, since even a slight change in indicators can adversely affect the plants, up to their death.
Compliance with the temperature regime in the greenhouse is the key to high yields
As a rule, for most plants, the most comfortable temperature is within from 16 to 25 ° C, and a deviation even by a degree, if it does not lead to the death of plants, their appearance will be very eloquent: in this case, symptoms of wilting begin to appear.
It is important to regulate not only the air temperature in the greenhouse, but also the temperature of the soil. The speed and intensity of assimilation of nutrients from the soil depends on the interaction of these two indicators, respectively, they directly affect the growth and development of plants.
The optimum soil temperature is practically in the same range as from 13 to 25 ° C and is determined, as a rule, by what kind of crop is grown.
Attention! Temperature changes in the soil are sometimes even more noticeable for plants. For example, a decrease slows down or stops vegetation, and an increase affects the absorption of moisture by plants.
Methods, methods and devices for regulating the temperature regime in the greenhouse
The most convenient option is to make automatic temperature control in the greenhouse, taking into account the readings of the sensors connected to all systems. For this, various models of automatic regulators are used.
Some of the modern models are programmable:
- for a specific type of plant;
- for day and night modes;
- with the possibility of SMS notifications, etc.
On such models, all information is displayed on the board, and making adjustments, programming or reprogramming is easy and quick, thanks to an intuitive menu.
Advice. In private, it is economically unprofitable to buy an expensive system. In this case, for example, a mechanical apparatus or a home-made temperature controller in the greenhouse can be successfully used, which, meanwhile, successfully cope.
How to choose the right thermostat
A properly sized regulator (thermostat) must take into account several factors.
- The power of the apparatus, which should be:
- sufficient and appropriate for the capacity of the heating system;
- fit the size of the greenhouse;
- be complete or compatible with sensors and their quantity in which there is a need.
- Ease of installation and operation:
- functional capabilities of the device:programming; control; control of current parameters;degree of autonomy.
- timing of installation work.
How the thermostat works and works
Any thermostats for - temperature control unit based on the readings of the connected sensors. Such a device can be assembled by yourself. For this, a greenhouse thermostat circuit can be used, presented in professional literature and on specialized sites on the Internet.
All thermostats, even self-assembled ones, work according to the following principle: a signal processed based on the readings of the sensors is sent from the device to the system, for example, heating, about an increase or decrease in power.
How to properly adjust the device
For a self-assembled device using sensors, a so-called setup process must be carried out. In this case, the instruction should be clearly followed, according to which the process is reduced to the graduation of the resistor scale.
The essence of the setup is as follows:
- the sensors are placed in heated water with a known temperature;
- the data is used to calibrate and synchronize the scale;
- then the sensors can be installed and connected to the thermostat.
A simple, affordable and effective way to control temperature
For summer residents who have greenhouses on their site, but visit them only once a week, it is rational to assemble a device, the price of which is much lower compared to industrial counterparts. However, such devices meet all the requirements for them, they are reliable and accurate.
Solar energy serves as a power source for them, and air acts as a sensor. The regulator is a housing divided into sectors made of duralumin, an inspection cover with a push link and a rotary valve.
Further, an expansion tank, connected to a rubber chamber, for example from a ball. When the air is heated above 25 ° C, the chamber is filled, which, in turn, opens the greenhouse transom to the corresponding width. When the temperature drops, the opposite process occurs.
How to quickly change the temperature in a greenhouse in an emergency
It is often necessary to regulate the temperature in greenhouses, especially in small home or summer cottages, using some other available methods.
As a rule, such events are relevant when there is an urgent need to raise or lower temperatures, for example, during the off-season.
- The temperature can be easily increased, for example, in one of the following ways or in combination:
- covering with an additional layer of film,
- the use of a portable structure, under which plants are hidden in the greenhouse itself,
- the use of means for covering the soil, such as manure, film, etc.
- Activities such as:
- provide sufficient fresh air access;
- spray the greenhouse with chalk solution;
- in the summer, watering and spraying plants early in the morning, immediately after sunrise.
Conclusion
For each greenhouse, the calculation and scheme of temperature controllers must be done separately, depending on the design of the room, heaters, fans and crops that will be grown. Some options can be seen in the video in this article.
A thermostat for greenhouses is necessary to ensure comfortable conditions for the growth and development of various crops. One installation of heating equipment is not enough. The temperature to which air, water and soil are heated must be monitored and regulated around the clock. The fact is that, for example, the temperature in the greenhouse should be higher during the day and lower at night. Accordingly, the operating mode of the heating system should also change. It depends on external conditions, ambient temperature.
The thermostat in the greenhouse allows you to grow plants in any weather, providing a comfortable temperature.
Not only the air temperature inside the greenhouse should be monitored and regulated, but also the temperature of the soil in it. The ratio of these two parameters determines the intensity of plant growth and development, since the activity of assimilation of useful substances by them directly depends on it. For most plants, the following values are most comfortable:
- for air 16-25 ° С;
- for soil 13-25 ° C.
The need for temperature control and regulation also arises in the summer. The provision of the necessary conditions in this case is usually carried out using a controlled ventilation system.
The principle of operation of thermostatic devices
The principle of operation of structures of this kind is quite simple: a signal is sent to the actuator, which, depending on the type of this installation, can cause the following reactions:
- if it is a heating system, increase or decrease its power;
- enable or disable forced ventilation;
- open or close the natural ventilation curtains for ventilation;
- turn on or off the heating system for soil and water for irrigation.
This signal is generated by a thermostat relay that receives information from sensors installed in the greenhouse. A favorable microclimate for plants is determined not only by the ratio of temperature and illumination, but also by the value of air humidity. For this reason, the most perfect system will be a system that provides automatic regulation of parameters taking into account the readings of three types of sensors: temperature, illumination and humidity. The following devices are most often used as sensors:
- A thermistor (thermistor) is most often used as a temperature sensor. In home-made designs, the p-n junction of a semiconductor diode or transistor is often used as a temperature-sensitive element, since its direct resistance depends on temperature.
- The light sensor is most often a photoresistor, but in self-made designs, the same p-n junction is sometimes used, the reverse resistance of which is highly dependent on the illumination. To allow light to access the junction, the cap of the metal case is usually cut off at the transistor, and the paint is washed off the glass from the diode.
- Industrial sensors of the third necessary parameter often use the dependence on the humidity of the dielectric constant of the medium between the capacitor plates. In addition, the change in resistance upon contact with humid air of substances such as alumina can be used. The fact that the length of a synthetic fiber or defatted human hair changes with a change in the relative humidity of the air and so on is also used. In home-made devices, such a sensor is often a piece of foil-clad fiberglass with grooves cut in it. With increasing humidity, its resistance decreases.
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Types of industrial thermostats
Thermoregulators for greenhouses of varying degrees of complexity can be purchased in appropriate stores, or assembled by hand (if you have the necessary skills).
Today, there are three types of models of these devices:
- Sensor temperature controllers are quite expensive multifunctional systems. Designed primarily for large greenhouse complexes. It is possible to set a variety of programs that control the operation of the heating system. They can even take into account the heat generated by the liquid manure. They have a wide variety of functions, usually equipped with a backlit display.
- Electronic thermostats are devices, the number of functions of which is noticeably less than that of regulators of the previous class, but the price, respectively, is lower. Usually equipped with a switch that makes it possible to set a specific heating mode. For convenience, they are often supplemented with a liquid crystal display with the necessary information.
- Mechanical thermostats are the simplest in their design, but often no less effective devices than their electronic counterparts. It is economically inexpedient to purchase expensive equipment for a small summer cottage greenhouse. But an inexpensive mechanical thermostat would be the most suitable option for her.
When purchasing any of these devices, you should pay special attention to their characteristics:
- the power of the serviced heating installation and its capabilities;
- the specificity of the installations that may be required;
- whether this device has all the required functionality;
- ease of operation and suitable appearance.
In most cases, the so-called thermostats, which have become one of the most important ingredients required for a good harvest.
What is thermoregulation in a greenhouse for?
In greenhouses, it is very important to maintain the temperature of the air, as well as the soil layer at a certain level, regardless of what kind of vegetable crop is grown in them.
Thanks to the provision of round-the-clock temperature control taking into account the type of plant grown in this device, you can get a fairly high yield.
Otherwise, with sudden changes in air temperature, freezing, and overheating of the soil layer, it makes no sense to use greenhouses.
After all, a decrease in temperature is the reason that the greens begin to absorb all the necessary nutrients from the soil much worse, and its increase leads to the fact that the plant either begins to grow rapidly or almost completely burns out.
By regulating the temperature in the greenhouse and constant monitoring of various parameters inside the tempitsa, the maximum development of the root system in a particular grown vegetable crop and their correct growth are achieved. In addition, the correct formation of fruits takes place and the timing of their ripening decreases.
For each type of plant, it is necessary to maintain a certain temperature of air and soil. In most cases, such indicators differ by a couple of degrees.
On average, the temperature in greenhouses is set at + 20 + 22 ° С. However, when choosing the most optimal mode, it is imperative to take into account the peculiarities of the plant culture grown in this structure.
How to regulate?
Today, there are special devices that are designed to automatically regulate the temperature regime inside the greenhouse.
But this equipment sometimes turns out to be too expensive in order to export it, especially if the greenhouse is not one.
In such cases, you can use cheaper and fairly simple methods that allow you to effectively lower or increase the temperature. In addition, it should be noted that some of them are more effective in comparison with modern technical devices.
In order to quickly raise the air temperature in a structure, you must use one of the following methods:
- Covering the greenhouse with an additional layer of polyethylene film in order to create an air gap that does not react to various environmental factors.
- Inside, a so-called secondary greenhouse is made - an additional cover is attached to the previously prepared structure, so that it is located directly above the surface of the plants.
- Thorough mulching of the soil layer makes it possible to attract heat to the plants using plastic wrap or black spunbond.
There is also methods to lower the temperature level if necessary inside greenhouses. The most common ones include:
- Greenhouses should not be made too long.
- Free access of air currents from the environment should take place through the gables.
- The structure is treated with a special chalk solution.
- Watering grown vegetables with plenty of water in the morning.
If automatic devices are used, then you can use such effective methods as correct control of the system intended for heating the greenhouse, as well as opening the vents after the appropriate command is given by the thermostat.
Greenhouse temperature controller options
Nowadays are produced thermostats of several varieties:
- Electronic.
- Sensory.
- Mechanical.
They differ from each other in terms of design and the principle of operation of the mechanism.
Greenhouse thermostat mechanical is a device whose task is to regulate the operation of climatic equipment in order to maintain certain temperature parameters.
It can be used not only for heating, but also for cooling the greenhouse.
Its peculiarity lies in the fact that a separate device is completely independent. In most cases, the device is manufactured in the form of external wiring equipment, mounted directly in the greenhouse itself.
On electronic thermostats the role of the sensor is played by a thermistor. The main advantage of devices of this type is called the accuracy in maintaining the temperature regime. After all, they are able to react to even the smallest changes.
Thus, you can significantly save on the consumption of electricity, which is used to heat the greenhouse.
With sensor thermostats you can set a specific operating time of the heating system. In addition, at different times, you can set a different, most suitable temperature. Such devices, as a rule, are programmed for a fairly long period of time - it is possible to set the desired mode for a week, and in some models, even longer.
And here is a video about a homemade thermostat for a greenhouse (temperature control by opening the vents).
Operating principle
The main structural element of the thermostat, regardless of its type, is a special temperature control unit, which functions taking into account the measurement readings of the sensors connected to it.
A simple thermostat for a greenhouse: a diagram.
The device operates according to the following scheme: the heating system receives a signal from the thermostat, which automatically processes the readings measured by several sensors. As a result, the power of the system can either decrease or increase.
Thermoregulators are an irreplaceable thing in order to get a high yield of vegetables, berries and herbs grown in greenhouses.
It tells about an automatic greenhouse window with your own hands.
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A comfortable microclimate for plants in the greenhouse can be controlled with a thermostat. This device may well provide ventilation for the greenhouse in your absence. In order to make a thermal actuator from a shock absorber and other improvised materials with your own hands, you do not need special knowledge. And you can't do without drawings and videos published here.
What is a thermostat and what is it for
The essence of the thermostat is clear from the name, it is designed to regulate the temperature in the room. Thermoregulators (thermal drives) are indispensable for a busy summer resident who cannot devote much time to their greenhouse.
In winter, devices installed on heating systems monitor air and soil temperatures using special sensors. And in summer, thermal drives regulate ventilation in the greenhouse. Some (one-channel, two-channel and three-channel) deal with turning multiple fans on and off. Others open and close the vents themselves, depending on the heating or cooling of the air. Let's look at three simple options for ventilation thermostats that you can do yourself without any problems. More reliable - from a gas shock absorber (two types), and very simple - from plastic bottles and from an inflatable ball.
Thermal actuator from gas shock absorber - option 1
Quite often, the automation for the ventilation of the greenhouse is assembled literally out of nothing. The principle of operation of this option is the use of a substance that reacts to cooling or heating by contraction or expansion. In this case, automobile oil. To build a thermal drive, you will need:
- automotive shock absorber piston or automotive gas spring;
- metal pipe for oil;
- two taps.
Stages of work:
- On two pieces of pipe, you need to cut the threads and connect them with a tee.
- Seal the ends of the pipes with two plumbing plugs.
- In the gas shock absorber, it is necessary to cut off the stud, drill a hole and cut an M10 thread in it.
- Having inserted a 10-inch drill into the drill, you need to drill through the bolt from the brake hose and the plug.
- Tighten the screw with the lock nut and the plug.
- Screw the free part of the bolt into the thread in the shock absorber.
- Connect the plug with an internal thread to the tee with a squeegee with a lock nut.
- The thermostat is ready. In order to pour engine oil into it, you just need to unscrew one end cap.
- After filling with oil, the thermostat can be installed under the window.
Diy thermal actuator from a plastic bottle
This economical device is well suited for small greenhouses with two to four transoms.
You will need:
- two plastic bottles. One - with a capacity of 5 liters., The second - 800 ml. or 1 l.;
- black film;
- two pipes and a thin PVC tube about a meter long;
- wooden plank.
When a five-liter bottle is heated, the pressure in it increases, air expands and is transferred to the small bottle. She straightens, lifting the board, and she pushes the frame out. The higher the temperature in the greenhouse, the higher the pressure.
Thermal actuator from cylinders and rubber ball
This original ventilation device is very easy to make with your own hands. And you will need for this:
- wooden box with a lid;
- an ordinary inflatable ball;
- two cylinders;
- hose;
- board.
Stages of work:
- Connect a hose with a length equal to the height of the greenhouse to the communicating metal cylinders.
- Put the other end of the hose over the nipple of the inflatable ball.
- Put the deflated ball into the box so that when inflating, it pushes the lid.
- Nail a board to the lid of the box, and connect it to the window.
- You need to install the cylinders under the ceiling of the greenhouse, and the ball is in the box below, under the transom. As soon as the cylinders heat up, the ball will inflate and open the window.
In order to choose a particular device, you need to take into account its pros and cons. Thermal drives from bottles and a ball are less reliable, because everything depends on tightness there.
Shock absorber devices are more durable, but they are also more difficult to make. All the described self-made thermostats will help you ventilate the greenhouse in your absence.
Thermal drive for a greenhouse - video
In industrial greenhouses, a whole system of sensors monitors the stability of the microclimate. In private facilities, plants have to be saved from heat or cold manually - by ventilating or regulating the heating system. Round-the-clock service is not only tedious, but also tightly ties the summer resident to the beds, so sooner or later he has to think about whether it is possible to make a thermostat for the greenhouse with his own hands, and how reliably it can function.
It would seem, why not buy a ready-made device, because the market today offers many models, the price of which starts from 400 rubles? In fact, branded controllers, whose reliability you can trust, are expensive, and cheap analogs can fail at the most crucial moment, which is fraught with the loss of the entire crop.
Having assembled and tested the thermostat with your own hands, you can save money and be safe from its failure.
Automatic thermostat from the manufacturer
How to achieve the main goal - to adjust the temperature inside the greenhouse in automatic mode? The easiest way to do this is to open and close the vents at the right time.
Timely ventilation helps to keep the air temperature within a certain range, comfortable for the normal growth and fruiting of crops.
A lot of devices have been invented for automatic opening of the vents: some of them are created from improvised materials - plastic bottles, empty cylinders; for others, you need to stock up on some parts in advance, such as a car gas shock absorber. In both cases, the price of the device is minimal, but the level of its operation will need to be checked quite often.
Airing is the usual way of thermoregulation
Classic greenhouse thermostats, if necessary, limit the access of the coolant to the heating elements, or, conversely, contribute to a rapid rise in temperature. Thus, hypothermia and overheating of plants are excluded, and excess energy is not consumed. This significantly reduces the cost of heating the greenhouse, so this method of controlling the microclimate is preferable.
The principle of their operation, regardless of the type, consists in processing the readings of one or several temperature sensors and transmitting a signal to the actuator of the heating system, which then either reduces the power of work or increases it.
To create such a thermostat for a greenhouse with your own hands, you need knowledge of electronics and skills in assembling electrical circuits.
Homemade thermostat assembly
Video: How to assemble a thermostat yourself
Installation of thermostatic devices - mechanics and electronics
It is ideal when thermostats complement the work of fanlight thermal drives: in winter they turn off and turn on the heating, and in summer, the microclimate is controlled by opening and closing the vents. Thus, the summer resident can devote much less time to his greenhouse without fear for his harvest.
Pneumatic thermostat - removal of excess heat
The pneumatic device, the action of which is based on the ability of hot air to expand, is elementary in assembly and at the same time allows to solve the problem of thermoregulation for a long time. For its installation, the following elements are required:
- 2 paint cans with a capacity of 5–7 liters (with lids);
- several tubes from medical droppers;
- children's inflatable ball with a coverage of about 300 mm;
- thin plywood with a width of at least 300 mm;
- metal strips (strips) of any size;
- 3 copper tubes 50 mm long.
Schematic diagram of a pneumatic regulator
The assembly of a thermal actuator consists of a few simple steps:
- Seal cans by soldering or epoxy casting.
- Drill one hole to fit the copper tubing in one container and two in the other.
- Insert the tubes into the holes and seal the joints.
- To make a box of 300x300 mm from plywood. Leave it open on both sides.
- Cut the plywood plate to dimensions that best match the cavity of the box.
- Insert the plate inside the box and fix it with hinges.
- Attach the box with the open part to the window.
- Make a movable lever from two metal strips, one arm of which is rigidly attached to the window, and the other to the movable plate of the plywood box.
- Close the window and check the position of the plate - its angle of inclination relative to the walls of the box should be 45 degrees.
- Hang the tin containers under the roof and connect them with dropper tubes, while the length of the outgoing tube should cover the distance from the cans to the box.
It is necessary to close the entire system into a single mechanism in cool weather or in the evening. To do this, you need to put the ball in the box and inflate it exactly until the moment when, with further air injection, it starts to open the window.
After that, you should tightly connect the end of the outgoing tube with the ball and check the operation of the device when it gets warmer.
Pneumatic system in a different design
Gas shock absorber thermostat
By slightly modifying the air shock absorber from any passenger car (these are usually placed on the hoods or rear doors), you can get a device that can automatically open a transom or a window, thereby eliminating excess heat energy.
The part does not have to be new - just enough to keep the pressure in it. You also need to stock up on a brake hose and an empty car fire extinguisher in advance.
You can mount these parts into a single device in this way:
- Without breaking the tightness of the pneumatic cylinder, cut off the spherical part of its shank, leaving the maximum length.
- Drill a 2–3 mm diameter hole on the side of the formed end to bleed air from the cylinder cavity.
- Cut a thread on the shank (its pitch depends on the size of the thread on the existing brake hose).
- From a fire extinguisher (or an automobile cardan with a volume of 3 liters), build an oil reservoir with a connecting hole for a hose.
- Pour oil into the shock absorber and into the reservoir, and then connect them with a hose.
After installing the thermostatic system, test its functionality by temporarily increasing the heating output.
Homemade pneumatic regulator in the greenhouse
Electronics wonders - assembling a regulator from a household thermometer
To get at your own disposal a thermostat for a greenhouse, which controls the air temperature in a constant mode and transmits a signal about the need to change the operation of the heating system, you need to modify a conventional dial thermometer:
- Disassemble the thermal sensor so as not to damage it.
- Drill a hole with a diameter of 2.5 mm on the scale - in the area of the required temperature limit.
- Opposite it, construct a corner made of thin sheet metal with a 2.8 mm hole drilled in it.
- Install the phototransistor in the socket of the corner and attach them to the scale using the "Moment" glue.
- Fasten another angle under the hole to prevent the arrow from moving when the temperature rises.
- On the opposite side of the thermometer, install a 9 V light bulb. You can put a lens between the scale and the light bulb - this way the device will more accurately respond to the readings.
- Route the photocell wires through the central hole on the thermometer scale.
- Drill a hole in the housing for the bulb wires. Pass the tourniquet through the PVC sheath and secure with a clip.
- According to the standard scheme, assemble a voltage stabilizer and a photo relay with a GT109 transistor.
- Place the photo relay, power supply and thermal sensor on the base of the factory relay mechanism.
- On the outside of the common body, fix a toggle switch and a neon lamp to signal the start of heating.
Greenhouse pointer thermometer
A do-it-yourself thermostat for a greenhouse works on the principle of an electromagnet: a steel armature is pulled into a coil, and a switch (with a current of 2 A and a power of 220 V) activates an electromagnetic starter that supplies power to the heating devices.
Thermostat assembly diagram
The main disadvantage of an electronic thermostat for a greenhouse is its dependence on a source of electricity. If the power goes out in extreme heat or cold, you can lose all the plants.