Not one even the most well-built greenhouse will be able to perform its main function, growing plants, without the correct temperature regime. Today we will talk about the temperature regime in the greenhouse.

At the very beginning of our article, we want to say right away that the yield of plants is affected not only by the air temperature in the greenhouse, but also by the temperature of the soil (see Earth in the greenhouse: soil selection and care).

It is important to understand that various plants grow well and bear fruit strictly at a certain temperature.

Different plants - different temperatures

Many probably faced such a question that in a certain year some plants gave a rich harvest compared to other plants growing nearby.

It's all about the temperature, for some it was the most optimal, and for others it was either too high or too low.

Greenhouse - temperature advantage

But if on the open ground it is not possible to regulate the temperature for individual plants, then the greenhouse is a closed space in which it is possible to successfully regulate the temperature regime.

Proper placement of plants is an important task

That is why it is so important to properly plant plants in a greenhouse. If your greenhouse is large, then there will be a significant difference in temperature in various parts of it.

This can be successfully used by planting heat-loving plants in warmer places, and in cooler places, plants for which this temperature is optimal. For more information on how to grow different crops together, you can read: Peppers and Eggplants in the Same Greenhouse and Growing Cucumbers and Tomatoes in the Same Greenhouse).

temperature fluctuations

As in the open field, in the greenhouse there is a temperature difference between day and night. This difference is very important. Too large fluctuations can adversely affect plants and lead to their diseases, and in some cases even death.

Our reference - the limit of night and day mode should not exceed 4 - 8 ° С.

What is good for greens is bad for the fruit

Depending on the type of plants, the daily air temperature in the greenhouse should be 16 - 25 °C. Temperature directly affects growth, for example, a temperature increase of 10 ° C will increase the growth of greenery.

Do not rejoice, the roots and fruits at the same time develop much worse.

An increase to 40 ° C leads to a depressed state and possible death of the entire plant.

We were talking about air temperature.

Air is important - soil is just as important

The temperature regime of the soil is also important and should be within 14 - 25 ° C, everything also depends on the type of plant.

  • If the soil temperature drops and reaches 10 ° C, the plant will begin to experience phosphorus starvation.
  • Too high a temperature, exceeding 25 ° C, leads to difficult absorption of moisture by the roots.
  • With the right temperature regime, the root system of plants develops and functions correctly, which cannot affect the well-being of the whole plant.

temperature issue

Realizing that the temperature regime in the greenhouse is extremely important and the yield depends on it, many will wonder how to control the temperature and observe the most optimal regime in the greenhouse?

Automatic regulation - the solution to the temperature issue

As is clear from the above, visual compliance with all parameters is a very difficult and responsible task.

  • Therefore, the surest option would be to equip the greenhouse with automation.
  • Automatic temperature control in the greenhouse will relieve you of the worries of hourly control and measurement of air and soil temperature parameters in various places of the greenhouse.

Sometimes the temperature begins to rise above the required norm, and at this time you are not.

How to lower the temperature in the greenhouse to the required parameters?

Automation comes to the rescue. Currently, there are a large number of various electronic devices on sale, which we have already discussed earlier (see Thermoregulator for a greenhouse).

We build a temperature controller ourselves

But it is not necessary to purchase temperature control devices with electronic filling, such a device can be built by any person, even far from knowledge of electrical engineering.

Physics to the rescue

Today we will build a device that uses a simple law of physics - when heated, a substance expands in volume.

So, how to lower the temperature in the greenhouse using a homemade, simple device?

Materials - all from the farm

It is quite easy to make it at home. We will need:

  • Three liter jar 1 pc.
  • Liter jar 1 pc.
  • Copper tube with a diameter of 5 - 6 mm.
  • Lid for cans metal (for seaming) 1 pc.
  • Lid for jars polyethylene 1 pc.
  • Rubber hose (a hose from a dropper works well). The main condition is that the hose should fit tightly on the tube, be flexible and not be pinched.

Tool minimum

From the tool we need:

  • Soldering iron.
  • Seat for cans.
  • Hammer.
  • Pliers.
  • Thermometer.

Stage one - we make a thermosyphon

You can get to work.

  • Roll up a three-liter jar with a metal lid.
  • Drill a hole in the center of the cover of such a diameter that the copper tube fits snugly into the hole.
  • Insert the tube into the lid so that it does not reach the bottom of the jar by 3 - 5 mm.
  • While holding the tube in this position, solder it to the cap. The connection must be tight.

Calibrating the device

Our thermosyphon is ready. Before performing a complete installation of the entire device, it is necessary to check our siphon and obtain accurate data on its operation.

This is done as follows:

  • Pour a liter of water into a three-liter jar through a tube.

Our advice - understanding the complexity of pouring water through a tube with a diameter of 5 - 6 mm, we advise you to do the following. Pour a liter of water into the container. Put a hose on the tube and turn the jar upside down.

Suck the air out of the can through the hose, pinch the hose and lower its end into the collected water. Release the clamp. The water will go into the jar.

After performing this action several times, you will pump the required amount of water into the jar. Thus, later on, water is added to the device.

  • Place the jar in a bucket and fill it with water to such a level that the water does not reach the lid of the jar by 50 - 70 mm.
  • Put a hose on the copper tube, and lower the other end into a liter jar.
  • Put the bucket on the fire and heat the water, while controlling its temperature with a thermometer.
  • When the water in the bucket begins to heat up, the air and water in the jar will heat up.
  • The created pressure will begin to push water out of the three-liter jar, it will begin to flow through the hose into the liter jar.
  • When the temperature reaches 25 ° C, the fire must be turned off and the amount of water that has entered the liter container must be measured, this volume will be approximately 400 ml.

Principle of operation

You can collect our device. The principle of its work has already become clear.

  • When the temperature inside the greenhouse begins to rise, the water from the three-liter jar will begin to flow into the liter jar, which in turn acts as a counterweight.

Thus, an increase in the mass of a liter jar opens a window and ventilates the greenhouse. The higher the temperature, the more water enters and, therefore, the window opens more and more.

When the air temperature in the greenhouse begins to drop, a vacuum is created in the three-liter jar and the water from the one-liter jar is sucked back. Thus, the mass of a liter jar becomes smaller, and the window begins to close.

Assembly and installation

As you can see, the temperature controller for the greenhouse turned out to be quite simple, but nevertheless very effective.

  • A liter jar is hung from the window.
  • A plastic cover is put on it, in which a hole is made and a hose is inserted there. The end of the hose does not reach the bottom by 3 - 5 mm.
  • 200 ml of water is poured into a liter jar.

Weight adjustment

The only thing to do is to choose the right counterweight for the frame.

Everything is done by experience.

  • The weight of a liter jar and the water poured into it should not open the window.
  • But when water from a large jar begins to flow into a small one, the window should open.

Important - the cavity of a liter jar should be freely connected to atmospheric air. If the hose fits snugly in the plastic cover, make a hole in the cover next to it.

This system does not require special control. The only thing that needs to be done is to add water to a three-liter jar, the volume of which decreases due to evaporation.

Tomatoes, eggplants, cucumbers, strawberries - we solve the temperature issue

This unit is adjusted for tomato, but it can be adjusted to your desired temperature.

For example, the temperature for cucumbers in a greenhouse is different from the temperature regime for a tomato (see How to grow cucumbers and tomatoes in a greenhouse). During the germination period, the optimum temperature is 25 - 28 ° C.

With further cultivation, it is very important to ventilate the greenhouse on sunny days, while the temperature is 28 - 30 ° C, and on cloudy days it should fluctuate around 20 - 22 ° C.

This device will successfully cope with this task.

  • If you require that the temperature in your greenhouse does not exceed 20 ° C, adjust the device for this temperature regime. How to do this you probably already understand.
  • Make the counterweights removable and specify the temperature range for each, then you just need to change the counterweights, and the temperature in the greenhouse will be adjusted strictly according to the specified parameters.

Our advice is to put a water level mark on the jars, so it will be easy for you to determine the moment when you need to add water to the device.

By applying ingenuity and a system of levers, it is possible to make it possible to open several windows at the same time with this device.

Today we talked about how to build a temperature controller in a greenhouse on your own in just a few hours. At the same time, we did not need to get expensive and rare materials, we simply took advantage of what is always available in any household.

Air regulates temperature

Such devices are successfully used by many gardeners.

There is a device that works on this principle, but it uses air instead of water.

The device and principle of operation of the air regulator

It is arranged as follows.

  • Instead of a three liter jar, a metal container is used there, preferably aluminum. The container is sealed.
  • By increasing the temperature, the volume of air in the container increases and the air begins to flow through the hose into the rubber chamber. With success, you can use the camera from a soccer ball.
  • The camera expands and pushes the lever, which opens the window.

As you can see, the system is closed, sealed and does not communicate with the atmosphere..

  • As the air temperature in the greenhouse drops, so does the air pressure in the device.
  • The rubber chamber deflates, the lever moves back and the window closes.

Advantages and disadvantages

The advantage of this system is that it does not require control over the water level and works independently for a very long time.

Among the shortcomings, one can single out the fact that good tightness is required. Otherwise, the device simply will not work, and visually identifying a leak is quite difficult.

There are many ways to control - choose according to your liking

We have described several ways to independently solve the automation of your greenhouse. It's up to you to decide which method to use.

The most important thing is that you understand that the greenhouse, the temperature and humidity in it, directly affect the yield and health of your plants.

Good luck and a rich harvest!

To ensure the full development of plants in various greenhouses (especially with a year-round growing cycle), automated support for the temperature regime at a certain level is required. The formation and regulation of the external environment around the plants in the greenhouse is carried out simultaneously by several systems - ventilation, heating, moisturizing the air and soil, evaporative cooling, etc. We will describe how to make a thermostat in the greenhouse for all these systems in this article.

The control of these systems with subsequent adjustment is carried out using an air temperature controller, which is the most important part for obtaining a full-fledged crop, since even minimal changes in data can adversely affect the development of plantings, not excluding their death.

Scrupulous adherence to the temperature regime is a guarantee of decent harvests

The individual setting of the thermostat allows you to control the temperature level throughout the day, stabilizing the protective function of the boiler from overheating.

For most plantations, the most comfortable t is 16 - 25 ° C, any even slight deviations inhibit the development of plants, can lead to the development of diseases and wilting of plantings. Control is necessary not only for the air temperature of the greenhouse, but also for the t of the soil. These two indicators are dominant in creating conditions for the development of plants. The correct assimilation of nutrients in the soil depends on them, and they directly affect the growth and full development of plants.

For soil, one should adhere to the t range of 13 - 25 ° C, its exact indicators are determined depending on the variety of crop.

Please note! Changes in soil temperature are often more detrimental to plantings than a decrease in air temperature.

Fundamentals of the functioning of thermostatic devices

The principle of operation of structures of this type is straightforward: the control device receives a signal, after which different models of the installation can react in a similar way:

  • increase or decrease the power of the heating system;
  • turn on or off the ventilation of the room;
  • open or close natural ventilation sashes;
  • connect or completely turn off the heating of irrigation water and soil in the beds.

The appearance of signal pulses is carried out using a thermostat relay, which, in turn, receives data from sensors located in the greenhouse. As sensors, the following devices are most often used:

  • Thermistor is often used as a temperature sensor. In home-made installations, a p-n junction of a semiconductor transistor or diode is often used as a temperature-sensitive element.
  • A photoresistor is used as a light sensor, and in self-made designs, a p-n junction of a semiconductor transistor or diode can be used again, in which the reverse resistance directly depends on the illumination. To gain light access to the system, the cap from the metal case is cut off from the transistor, and the paint from the glass is removed from the diode.

  • Humidity parameters are regulated by industrial sensors, the indicators of which depend on the moisture permeability of the medium located between the capacitor plates. Changes in resistance during interaction with humidified air of aluminum oxide can also be taken into account. When adjusting air humidity, the result of a change in the length of a synthetic fiber or a human hair, etc. is also taken into account. For home-made devices, a similar sensor is a piece of foil fiberglass with cut grooves.

For your information! For small greenhouses for personal use, from the point of view of efficiency, it is absolutely unprofitable to purchase an expensive industrial design system. In such situations, do-it-yourself thermostats for greenhouses are successfully introduced.

Do-it-yourself principles of a thermostat for a greenhouse

Self-construction of a temperature controller is a very real task. But this will require elementary engineering knowledge and technical skills.

The main functioning of the system is carried out due to the introduction into the design of an 8-bit microcontroller of the PIC16F84A brand.

As a temperature sensor, a digital thermometer of the integral type DS18B20 is built in, which has an operating functionality in the range of t -55 - + 125 ° C. It is also possible to use a digital temperature sensor TCN75-5.0, which, in terms of parameters, compact size and relative lightness of design, is quite suitable for use in various automatic devices.

Such digital sensors, in fact, have insignificant measurement errors, therefore, the parallel use of several types of sensors makes it possible to observe the heating temperature with virtually no errors.

The ability to control the degree of load is carried out using a small-sized type of relay K1, which corresponds to an operating voltage of 12 V. A load is connected to the relay through the contacts and this allows it to switch it. Indication is made using any four-digit LEDs.

The degree of temperature reaction is set: SB1-SB2 (microswitches). The memory of the microcontroller is energy autonomous and stores the specified parameters. Applying the operating mode on the indicator liquid crystal panel of the device, you can see the current indicators of the measured temperature.

On a note! Such electronic thermostats are becoming more and more popular as they have the ability to sense the temperature at any point inside the greenhouse, and the monitoring sensor can be placed between plants, in the soil substrate, or hung near the roof. Such an extensive range of placement allows the thermostat to have accurate data on the state of the internal environment of the greenhouse.

How to make a thermostat for a greenhouse with your own hands

Craftsmen make simplified thermostats for personal greenhouses with their own hands. Before choosing a greenhouse automation scheme, you must first set the control object data.

The photo shows a thermostat circuit with two transistors of the type VT1 and VT2. The RES-10 relay is used as an output device. Temperature sensor - thermistor MMT-4.

One of the models of a do-it-yourself thermostat can be, for example, such a design. In it, as a temperature sensor, you can use a pointer thermometer that has undergone alteration:

  • The design of the thermometer is completely disassembled.
  • A hole of 2.5 mm is drilled in the regulation scale.
  • On the contrary, a phototransistor is installed in a specially designed corner made of thin tin or sheet aluminum, in which holes 0 2.8 mm are pre-drilled. Glue is applied to the phototransistor along the edge and placed in the socket.
  • A corner with a phototransistor is attached to the scale with Moment glue.
  • A stop is attached below the hole.
  • On the other side of the thermometer, a small 9 volt light bulb is installed. A lens is placed between the scale and the bulb - for a clear response of the device to the indicators.
  • Thin wires of the phototransistor are laid through the central hole of the scale.
  • For the light bulb wires, a hole is drilled in the plastic case. The tourniquet is threaded into a PVC tube and fixed with a clip.

In addition to the sensor, the thermostat must include a photo relay and a voltage stabilizer.

The stabilizer is assembled in the usual way. Photorelay is also not difficult to make. The GT109 transistor serves as a photocell.

A mechanism based on a converted factory relay is best suited. The work is carried out on the principle of an electromagnet, where the armature is drawn into the coil. The switch (2A, 220V) regulates the electromagnetic starter to supply power to the heating devices.

The photorelay and power supplies are placed in a common housing. A thermometer is attached to it. A toggle switch and a light bulb are attached to the front side, indicating the inclusion of heating elements.

Ventilation scheme

If the greenhouse is ventilated with an electric fan, two-position thermostats can be used. To create the desired mode of operation of the fan, connect an intermediate relay.

If windows are built into the greenhouse, they must be provided with an electric drive (electromagnets or electric motor mechanisms).

But it is easier to solve the issue of greenhouse ventilation when using direct-acting thermostats. In them, the actuator and thermostat are in the same device. However, for regulators of this type, the temperature variation can be up to 5 °C. To achieve a more precise adjustment, it is better to choose electronic regulators.

Humidity control

The ideal solution is to use soil moisture sensors and adjust irrigation according to the specified moisture. One of the principles of moisture measurement is based on taking into account changes in soil volume during moisture. An electronic regulator is also often connected. As a humidity sensor, a depolarizer with 3336L battery rods is mounted. At relative humidity, the resistance values ​​​​are somewhere around 1500 ohms. The variable resistor R1 helps the regulator to operate at a certain level, the resistor R2 helps to set the initial humidity.

Irrigation regulation

It is very tempting to control the irrigation system electronically, but it must be remembered that simple devices are more reliable. Simplified arrangement of irrigation is done by hand without the use of electronic circuits. This allows it to be used during power outages.

With electronic regulation of the water supply, an electric solenoid valve is used. The solenoid valve can be made independently. One of the designs can be seen in the photo.

1 - electromagnet; 2 - container; 3 - cargo; 4 - valve

The main drawback of the thermoregulation system is complete subordination to the power supply source. Power outages can cause plant death. To avoid such misunderstandings, spare power sources are used: generator, solar or battery, etc.

Also remember that all thermostats lose accuracy over time as they get older. Therefore, you need to check their accuracy every year. When checking the functioning of the thermostat, it is necessary to clean the sensors of the thermostat, carefully wipe all the leads and connections.

The thermostat for greenhouses is necessary to ensure comfortable conditions for the growth and development of various crops. One installation of equipment that provides heating 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, during the day the temperature in the greenhouse should be higher, and at night it should go down. Accordingly, the mode of operation of the heating system must 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 controlled and regulated, but also the temperature of the soil in it. The ratio of these two parameters determines the intensity of growth and development of plants, since the activity of assimilation of nutrients by them directly depends on it. For most plants, the most comfortable are the following values:

  • for air 16-25°С;
  • for soil 13-25°С.

The need for temperature control and regulation also arises in summer. Providing the necessary conditions in this case is usually carried out using a controlled ventilation system.

The principle of operation of temperature control 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 natural ventilation shutters for ventilation;
  • turn on or off the heating system of the soil and water for irrigation.

The occurrence of this signal is provided by a thermostat relay, which receives information from sensors installed in the greenhouse. A favorable microclimate for plants is determined not only by the ratio of temperature and light, but also by the amount of air humidity. For this reason, the most perfect system will be one 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 commonly used as sensors:

  1. As a temperature sensor, the thermistor (thermistor) is most often used. In homemade designs, a p-n junction of a semiconductor diode or transistor is often used as a temperature-sensitive element, since its direct resistance depends on temperature.
  2. The light sensor is most often a photoresistor, but home-made designs sometimes use the same p-n junction, the reverse resistance of which strongly depends on the illumination. To access light to the junction, the cap of the metal case is usually cut off from the transistor, and the paint from the glass is washed off from the diode.
  3. Industrial sensors of the third necessary parameter often use the humidity dependence of the dielectric constant of the medium between the capacitor plates. In addition, the change in resistance upon contact with moist air of substances such as alumina can be used. The fact of changing the length of a synthetic fiber or a defatted human hair with a change in the relative humidity of the air is also used, and so on. In home-made devices, such a sensor is often a piece of foil fiberglass with grooves cut into it. With increasing humidity, its resistance decreases.

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Types of industrial thermostats

Temperature controllers for greenhouses of varying degrees of complexity can be purchased at the appropriate stores, or assembled with your own hands (if you have the necessary skills).

Today, three types of models of these devices are produced:

  1. Touch 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 release of heat from decaying manure. They have a wide variety of functions, usually equipped with a backlit display.
  2. Electronic thermostats are devices, the number of functions of which is noticeably less than that of the regulators of the previous class, but the price is correspondingly lower. Usually equipped with a switch that allows you to set a specific heating mode. For convenience, they are often supplemented with a liquid crystal display with the necessary information.
  3. Mechanical thermostats are the simplest in their design, but often no less effective devices than their electronic counterparts. It is not economically feasible to purchase, for example, expensive equipment for a small country greenhouse. But an inexpensive mechanical thermostat for her would be the most suitable option.

When purchasing any of these devices, you should pay special attention to their characteristics:

  • power of the serviced heating installation and its capabilities;
  • specific settings that may be required;
  • whether this device has all the required functionality;
  • ease of operation and a suitable appearance.

When constructing a greenhouse, it should be remembered that in order to maintain the proper growth conditions for various crops, it is necessary to install special equipment (for example, a stove that can run on different fuels) that provides heating. But this is not enough, since the heating of air, water and soil needs to be controlled, to control the switching on and off of the system. For this, a thermostat is designed, which is installed inside the greenhouse.

The thermostat helps to control the temperature in the greenhouse, to control the turning on and off of the heating system.

Any do-it-yourself greenhouse heating requires careful control of the conditions day and night. At the same time, boilers or other heating devices must operate in a different mode, depending on the design of the greenhouse, the conditions of use (winter or summer). The selection of the temperature regime is provided by the heated areas of the greenhouse, types of crops. Therefore, the scheme of water heating of the greenhouse should be selected individually. If desired, solid fuel boilers can also be used for heating.

If manure is used to heat the soil, then soil temperature sensors should be connected to the thermostat.

Varieties of thermostats for greenhouses: from touch to mechanical

The thermostat can be assembled with your own hands or bought ready-made in a specialized store. Manufacturers today offer a temperature controller that can work in large and medium-sized polycarbonate greenhouses. The following models are offered:

  1. A modern touch temperature controller, which is used for large systems, is reliable, with the ability to quickly set any program that regulates heating. Such equipment is equipped with many functions, the temperature controller can be used even at night, its display has a backlight. He takes into account the heating of the soil due to manure. To do this, you need to make the appropriate settings.
  2. The electronic thermostat is equipped with an LCD display, which displays all the necessary information. As a result, the heating of the greenhouse will always correspond to the set indicator.
  3. The mechanical thermostat is the simplest, but no less effective device.

When buying a device such as a thermostat for a greenhouse, you need to pay attention to:

  • on the power of the unit, on the boilers and their capabilities;
  • installation features that the thermostat may require;
  • availability of all required functionality;
  • appearance and control.

For polycarbonate greenhouses, external and hidden thermostats are applicable, which are mounted indoors in different ways, controlling heating. It is worth considering the fact that manure is often used to heat the soil, and solid fuel boilers or other heating devices are used only for the winter months, when the air temperature can drop significantly. Here, the water heating scheme is also effective, which can be powered by electricity (that is, solid fuel boilers are not always used).

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Purpose and principle of operation

All heated greenhouses must have not only boilers for heating, but also means for controlling the microclimate and the operation of the stove. The temperature regulator helps to maintain a certain temperature for the greenhouse made of polycarbonate and any other material, allowing the plants to feel comfortable. As already noted, it is possible to use manure to heat the soil, but a water heating scheme is used to heat the air and water for irrigation.

The choice of any of these methods must be approached thoroughly, taking into account all the prospects of such methods.

The principle of operation of the device is quite simple: the boiler receives a signal to increase or decrease power. The receipt of this signal through the relay is provided by the thermostat, which collects all the data from the sensors placed around the greenhouse.

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Scheme of a thermostat for a polycarbonate greenhouse

The temperature controller for the greenhouse operates from two sensors: directly temperature and light. This must be taken into account, because at night the temperature in the room is lower and during the day it is higher. Accordingly, the heating conditions also change. The main parameters that a thermostat must have are as follows:

  • temperature range - + 15-50 ° C;
  • accuracy – 0.4°C;
  • illumination threshold - 500-2600 lux;
  • temperature drop of the environment at the transition of the illumination threshold - up to 12°C;
  • permissible deviations in the power supply of the device - up to 20%.

The greenhouse thermostat consists of a temperature control unit, a correction unit, which can be made on transistors. The switch allows you to change the temperature value for the greenhouse in accordance with the required growing conditions for certain crops. The relay for power control can be connected with contacts and with a heating device for the stove. The temperature controller has an output relay that controls all heating.

Greenhouse sensors include thermistors and photoresistors that respond to changing external conditions. It is especially good to use them for winter greenhouses, where conditions must be carefully monitored. All relevant settings, including soil heating from manure, can be set according to the instructions provided by the device manufacturer.

They begin to adjust the heating device, using their own hands, from grading the scale of the resistor. This is easy to do: the sensors are placed in heated water, which allows you to accurately determine the temperature. After that, the light sensor is calibrated. This can only be done with those lighting fixtures that are designed for a greenhouse (all photoresistors are very sensitive and spectrally dependent). Then the temperature controller can be assembled and mounted inside the greenhouse, it should be close to the stove or other heating device, but being isolated from it (an uninsulated boiler can knock down incoming data).

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How to work with a thermostat?

As a rule, all thermostats for a greenhouse are similar to each other. This is a special compact electronic device with which you can control the heating of polycarbonate greenhouses. Thermostats are made in such a way that it is very convenient and easy to work with them. The main steps are:

  1. Scroll through the menu using the corresponding button.
  2. Setting the parameters required for heating the greenhouse.
  3. Possibility of manual temperature control (suitable if you need to heat the greenhouse in winter, in summer on cold nights).
  4. Display with readings. It displays data, what kind of heating at the moment (for the stove and for air), operating time and shutdowns.
  5. Using special buttons, you can set any heating parameters, regulate the operation of the stove, boiler.
  6. Possibility to store the selected settings in memory for their quick activation.

In addition, with the help of a thermostat, you can control the boiler for heating the greenhouse. The algorithm of actions is as follows:

  1. When power is applied to the controller, all sensors are polled for real-time information. The controller compares the readings with the recorded data for night or day mode, and then selects the correct settings for the operation of the thermostat in the room.
  2. After about five seconds, the thermostat is activated, the boiler installed to heat the room and maintain the required temperature starts its work.
  3. When the temperature on the sensors in the polycarbonate greenhouse remains below the required one, that is, the existing heating is insufficient, the pump, heater comes into operation, a command is given to the corresponding unit to increase the fuel supply so that the system heating enters into active operation.

Each thermostat is equipped with a special circuit that allows you to act in emergency situations:

  1. When the temperature of the coolant is higher than the specified parameters, the pump turns on, and the heater turns off, the water starts to leave through the boiler (when installing water heating, if solid fuel boilers are used, the circuit may differ).
  2. If any sensor fails, the circuit is considered off, all pumps and heaters are turned off approximately 30 seconds after the signal is given.
  3. If the boiler is working, and the coolant temperature sensor is not working, then the boiler itself is switched to the minimum operation mode or is turned off with the corresponding signal.

A thermostat is a special device that is used to install a heating system for a greenhouse. The device is multifunctional, with its help you can not only set the required temperature for heating the air in the room, but also provide heating of water for irrigation, soil (here it is possible to use manure).

A state of the art greenhouse temperature controller has the ability to maintain the set conditions for any polycarbonate greenhouse with fine and precise control. Many thermostats in polycarbonate greenhouses turn on on their own if the specified conditions do not correspond to those that exist at a given time. The temperature controller for the greenhouse is connected to the controller and sources that heat the room. Manufacturers usually offer detailed installation instructions.

The temperature controller, which is mounted indoors (even if manure is allowed to heat the soil), is connected to all installed heat sensors, the controller, the boiler and the stove that provide heating. The result is complete temperature control.

In industrial greenhouses, a whole system of sensors monitors the stability of the microclimate. In private buildings, 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 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 purchase a ready-made device, because many models are offered on the market today, the price of which starts from 400 rubles? In fact, branded controllers, the reliability of which can be trusted, are expensive, and cheap analogues can fail at the most crucial moment, which is fraught with the loss of the entire crop.

By assembling and testing 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 - adjusting the temperature inside the greenhouse in automatic mode? The easiest way to do this is to open and close the windows at the right time.

Timely ventilation helps to keep the air temperature in a certain range, comfortable for the normal growth and fruiting of cultivated crops.

Many devices have been invented to automatically open the windows: some of them are made from improvised materials - plastic bottles, empty cylinders; for others, you need to stock up on some parts in advance, for example, an automobile 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.

Ventilation - 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 increase 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.

Their principle of operation, regardless of the type, is to process the readings of one or more temperature sensors and transmit 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 the thermostat yourself

Installation of thermostatic devices - mechanics and electronics

Ideally, when thermostats complement the operation of fanlight thermal actuators: in winter they turn off and turn on heating, and in summer the microclimate is controlled by opening and closing the windows. Thus, a summer resident can devote much less time to his greenhouse without fear for his crop.

Pneumatic thermostat - removal of excess heat

The pneumatic device, whose action is based on the ability of hot air to expand, is elementary in assembly and at the same time allows solving the problem of thermoregulation for a long time. For its installation, the following elements are required:

  • 2 cans of paint 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 the pneumatic regulator

Assembling a thermal drive consists of a few simple steps:

  1. Seal the cans by soldering or potting with epoxy.
  2. Drill one hole the size of the copper tubes in one container and two in the other.
  3. Insert the tubes into the holes and seal the joints.
  4. Make a plywood box measuring 300x300 mm. Leave it open on both sides.
  5. Cut the plywood plate to the dimensions that correspond to the cavity of the box as much as possible.
  6. Insert the plate inside the box and fix it with loops.
  7. Attach the box with the open part to the window.
  8. From two metal strips, make a movable lever, one shoulder of which is rigidly attached to the window, and the second to the movable plate of the plywood box.
  9. 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.
  10. Hang tin containers under the roof and connect them with tubes from droppers, 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 begins to open the window.

After that, you should hermetically connect the end of the outgoing tube with the ball and check the operation of the device when it warms up.

Pneumatic system in another design

gas shock absorber thermostat

By slightly modifying the pneumatic shock absorber from any passenger car (these are usually placed on hoods or rear doors), you can get a device that can automatically open a transom or window, thereby eliminating excess heat energy.

The spare part does not have to be new - it is enough that pressure remains 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 in a single device in this way:

  1. Without violating the tightness of the pneumatic cylinder, cut off the spherical part of its shank, leaving the maximum length.
  2. From the side of the formed end, drill a hole with a diameter of 2–3 mm to bleed air from the cylinder cavity.
  3. Cut the thread on the shank (its pitch depends on the size of the thread on the existing brake hose).
  4. From a fire extinguisher (or a car cardan with a volume of 3 liters), build an oil reservoir with a connecting hole for a hose.
  5. Pour oil into the shock absorber and reservoir, 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

The wonders of electronics - assembling a regulator from a household thermometer

To get at your 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 pointer thermometer:

  1. Disassemble the temperature sensor so as not to damage it.
  2. Drill a hole with a diameter of 2.5 mm in the scale - in the area of ​​\u200b\u200bthe required temperature limit.
  3. Opposite it, construct a corner of thin tin with a 2.8 mm hole drilled in it.
  4. Install the phototransistor in the socket of the corner and attach them to the scale using Moment glue.
  5. Under the hole, fix another corner that prevents the arrow from moving when the temperature rises.
  6. 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 indicators.
  7. Lay the wires of the photocell through the central hole of the thermometer scale.
  8. Drill a hole in the housing for the light bulb wires. Thread the tourniquet into the vinyl chloride sheath and secure with a clip.
  9. According to the standard scheme, assemble a voltage stabilizer and a photo relay with a GT109 transistor.
  10. Place the photorelay, power supply and temperature sensor on the basis of the factory relay mechanism.
  11. On the outside of the common body, fix a toggle switch and a neon light to signal the start of heating.

Pointer thermometer for greenhouse

A do-it-yourself thermostat for a greenhouse works on the principle of an electromagnet: a steel anchor 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 electricity goes out in extreme heat or cold, you can lose all the plants.