Automatic temperature control systems. Devices for automatic temperature control in rooms

According to the principle of regulation systems automatic regulation are divided into four classes.

1. Automatic stabilization system - a system in which the controller maintains a constant set value of the controlled parameter.

2. Program control system - a system that provides a change in the controlled parameter according to a predetermined law (in time).

3. Tracking system - a system that provides a change in the controlled parameter depending on some other value.

4. Extreme control system - a system in which the controller maintains the value of the controlled variable that is optimal for changing conditions.

To regulate the temperature regime of electric heating installations, systems of the first two classes are mainly used.

Automatic temperature control systems can be divided into two groups according to the type of action: intermittent and continuous regulation.

Automatic regulators for functional features are divided into five types: positional (relay), proportional (static), integral (astatic), isodromic (proportional-integral), isodromic with advance and with first derivative.

Positional regulators are referred to as intermittent ACS, and other types of regulators are referred to as continuous ACS. Below are the main features of positional, proportional, integral and isodromic controllers, which are most widely used in automatic temperature control systems.

(Fig. 1) consists of a control object 1, a temperature sensor 2, a programming device or a temperature level setter 4, a controller 5 and an actuator 8. In many cases, a primary amplifier 3 is placed between the sensor and the programming device, and between the controller and the actuator - secondary amplifier 6. Additional sensor 7 is used in isodromic control systems.

Rice. 1. Functional diagram of automatic temperature control

Positional (relay) temperature controllers

Positional regulators are those in which the regulatory body can occupy two or three specific positions. In electric heating installations, two- and three-position regulators are used. They are simple and reliable in operation.

On fig. 2 shows a schematic diagram of two-position air temperature control.

Rice. 2. circuit diagram two-position air temperature control: 1 - control object, 2 - measuring bridge, 3 - polarized relay, 4 - motor excitation windings, 5 - motor armature, 6 - reducer, 7 - calorific.

To control the temperature in the regulated object, the thermal resistance TS is used, which is included in one of the arms of the measuring bridge 2. The values ​​​​of the bridge resistance are selected so that at a given temperature the bridge is balanced, that is, the voltage in the diagonal of the bridge is zero. When the temperature rises, the polarized relay 3, included in the diagonal of the measuring bridge, turns on one of the windings 4 of the DC motor, which closes the air valve in front of the heater 7 with the help of a gearbox 6. When the temperature drops, the air valve opens completely.

With two-position temperature control, the amount of heat supplied can be set only at two levels - maximum and minimum. The maximum amount of heat must be more than necessary to maintain the desired controlled temperature, and the minimum must be less. In this case, the air temperature fluctuates around the set value, that is, the so-called self-oscillatory mode(Fig. 3, a).

The lines corresponding to temperatures τ n and τ in define the lower and upper boundaries of the dead zone. When the temperature of the regulated object, decreasing, reaches the value τ n, the amount of heat supplied instantly increases and the temperature of the object begins to increase. Having reached the value τ in, the regulator reduces the heat supply, and the temperature drops.

Rice. 3. Time response of on-off control (a) and static response of on-off controller (b).

The rate of temperature increase and decrease depends on the properties of the regulated object and on its time characteristic (acceleration curve). Temperature fluctuations do not go beyond the deadband if changes in heat supply immediately cause temperature changes, that is, if there is no delay of the controlled object.

With a decrease in the dead zone, the amplitude of temperature fluctuations decreases down to zero at τ n = τ c. However, this requires that the heat supply be varied at an infinitely high frequency, which is extremely difficult to implement in practice. In all real objects of regulation there is a delay. The process of regulation in them proceeds approximately as follows.

When the temperature of the regulated object drops to the value τ n, the heat supply instantly changes, however, due to the delay, the temperature continues to decrease for some time. Then it rises to the value τ at which the heat supply instantly decreases. The temperature continues to rise for some time, then, due to the reduced heat supply, the temperature drops, and the process is repeated again.

On fig. 3, b is shown static characteristic of on/off controller. It follows from it that the regulatory impact on the object can take only two values: maximum and minimum. In the considered example, the maximum corresponds to the position at which the air valve (see Fig. 2) is fully open, the minimum - when the valve is closed.

The sign of the control action is determined by the sign of the deviation of the regulated value (temperature) from its set value. The magnitude of the control action is constant. All two-position controllers have a hysteresis zone α, which occurs due to the difference in the operating and releasing currents of the electromagnetic relay.

Example of using on/off temperature control:

Proportional (static) temperature controllers

In cases where high control accuracy is required or when a self-oscillating process is unacceptable, apply controllers with continuous control process. These include proportional regulators (P-regulators) suitable for controlling a wide variety of technological processes.

In cases where high control accuracy is required or when a self-oscillatory process is unacceptable, regulators with a continuous control process are used. These include proportional regulators (P-regulators), suitable for regulating a wide variety of technological processes.

In automatic control systems with P-regulators, the position of the regulatory body (y) is directly proportional to the value of the controlled parameter (x):

y=k1х,

where k1 is the proportionality factor (controller gain).

This proportionality takes place until the regulating body reaches its extreme positions (limit switches).

The speed of movement of the regulating body is directly proportional to the rate of change of the controlled parameter.

On fig. 4 shows a schematic diagram of a system for automatically controlling the room temperature using a proportional controller. The room temperature is measured by a resistance thermometer TC included in the measuring bridge circuit 1.

Rice. 4. Scheme of proportional air temperature control: 1 - measuring bridge, 2 - control object, 3 - heat exchanger, 4 - capacitor motor, 5 - phase-sensitive amplifier.

At a given temperature, the bridge is balanced. When the controlled temperature deviates from the set value, an unbalance voltage appears in the bridge diagonal, the magnitude and sign of which depend on the magnitude and sign of the temperature deviation. This voltage is amplified by a phase-sensitive amplifier 5, at the output of which the winding of a two-phase capacitor motor 4 of the actuator is switched on.

The actuator moves the control element, changing the flow of coolant into the heat exchanger 3. Simultaneously with the movement of the control element, the resistance of one of the arms of the measuring bridge changes, as a result of which the temperature changes, at which the bridge is balanced.

Thus, due to rigid feedback, each position of the regulatory body corresponds to its own equilibrium value of the controlled temperature.

A proportional (static) controller is characterized by residual uneven regulation.

In the case of an abrupt deviation of the load from the set value (at the moment t1), the controlled parameter will come after a certain period of time (the moment t2) to a new steady value (Fig. 4). However, this is possible only with a new position of the regulatory body, that is, with a new value of the controlled parameter, which differs from the set value by δ.

Rice. 5. Time characteristics of proportional control

The disadvantage of proportional controllers is that each parameter value corresponds to only one specific position of the regulator. To maintain the set value of the parameter (temperature) when the load (heat consumption) changes, it is necessary that the regulating body take a different position corresponding to the new load value. This does not happen in a proportional controller, which results in a residual deviation of the controlled variable.

Integral (astatic regulators)

Integral (astatic) such regulators are called in which, when the parameter deviates from the set value, the regulating body moves more or less slowly and all the time in one direction (within the working stroke) until the parameter again takes the set value. The direction of stroke of the regulating body changes only when the parameter passes through the set value.

In integral regulators electric action Usually, a dead zone is artificially created, within which a change in the parameter does not cause movements of the regulatory body.

The speed of movement of the regulating body in the integral regulator can be constant and variable. A feature of the integral regulator is the absence proportional connection between the established values ​​of the controlled parameter and the position of the regulating body.

On fig. 6 shows a schematic diagram of an automatic temperature control system using an integrated controller. In it, unlike the proportional temperature control circuit (see Fig. 4), there is no hard feedback.

Rice. 6. Scheme of integrated air temperature control

In an integral controller, the speed of the regulating body is directly proportional to the deviation of the controlled parameter.

The process of integral temperature control with an abrupt change in load (heat consumption) is shown in fig. 7 with the help of time characteristics. As can be seen from the graph, the controlled variable with integral control slowly returns to the set value.

Rice. 7. Time characteristics of integral regulation

Isodromic (proportional-integral) controllers

Isodromic regulation has the properties of both proportional and integral regulation. The speed of movement of the regulating body depends on the magnitude and speed of the deviation of the controlled parameter.

If the controlled parameter deviates from the set value, the regulation is carried out in the following way. Initially, the regulating body moves depending on the magnitude of the deviation of the controlled parameter, that is, proportional regulation takes place. Then the regulating body makes an additional movement, which is necessary to eliminate the residual non-uniformity (integral regulation).

An isodromic air temperature control system (Fig. 8) can be obtained by replacing the rigid feedback in the proportional control circuit (see Fig. 5) with an elastic feedback (from the regulator to the feedback resistance slider). Electrical feedback in the isodromic system is carried out by a potentiometer and is introduced into the control system through a circuit containing resistance R and capacitance C.

During transient processes, the feedback signal, together with the parameter deviation signal, affects the subsequent elements of the system (amplifier, electric motor). When the regulating body is stationary, in whatever position it is, as the capacitor C is charged, the feedback signal decays (in the steady state it is equal to zero).

Rice. 8. Scheme of isodromic air temperature control

It is typical for isodromic control that the non-uniformity of control ( relative error) decreases with increasing time, approaching zero. In this case, the feedback will not cause residual deviations of the controlled value.

Thus, isodromic regulation leads to a significant best results than proportional or integral (not to mention positional control). Proportional control due to the presence of rigid feedback occurs almost instantly, isodromic - slowly.

Software systems for automatic temperature control

To implement program control, it is necessary to continuously influence the setting (set point) of the controller so that the controlled value changes according to a predetermined law. For this purpose, the controller tuning unit is supplied with a software element. This device serves to establish the law of change of the given value.

During electric heating, the ACS actuator can act to turn on or off sections of the electric heating elements, thereby changing the temperature of the heated installation in accordance with a given program. Software control of air temperature and humidity is widely used in artificial climate installations.

Automatic regulation is very convenient. With the help of a thermostat for greenhouses, you can maintain the required air temperature in the building.

Types of thermostats and their characteristics

There are many types of thermostats. To make the right choice, you need to know their features. There are 3 main types.

1. Electronic thermostat. It has a liquid crystal display, which makes it possible to obtain accurate information about the status.
2. Sensory devices. The good thing is that you can set a work program in them, which makes it possible to create different temperature in different time days.
3. mechanical product. Most easy installation to control soil temperature. In this case, the temperature is set once, and then you simply adjust it. Perfect option for small greenhouses.

How to choose a thermostat

When choosing a thermostat, you should be guided by what you want to receive in the end. First of all, you should pay attention to the following characteristics:

• installation features;
• control method;
• appearance;
• power;
• the presence or absence of additional functions.

When choosing thermostats for greenhouses Special attention power is worth it. It must be greater than the required ground heating power. Take with a margin! In this case, all work is controlled by a sensor. He can be:

• external;
• hidden.

A chain can consist of several elements. Appearance thermostats are also different. Installation can be either hinged or hidden.

Installation Features

When installing the system with your own hands, you should know that the regulator operates from sensors - illumination and temperature. During the day, the temperature in the building will be higher, at night it will be lower. Depending on this, the heating also changes. The parameters for the thermostat are:

• illumination limit - from 500 to 2600 lux;
• deviation in the power supply of the device - up to 20%;
• temperature range - from +15 to 50 degrees;

• at the transition of the illumination limit, the difference in temperature value is up to 12 degrees;
• accuracy is about 0.4 degrees.

When installing the system with your own hands, you should know that the thermostat includes a correction unit and a temperature control unit. You can run them on transistors. The switch allows you to change the temperature. The relay can be combined with a heating device for the stove using contacts. The controller may have an output relay that controls the heating.

The sensors include photoresistors and thermistors. They respond to various changes in environment. You can set the settings according to the instructions provided by the manufacturer.

You should set up the installation with your own hands, starting with grading the scale of the resistor. First, the sensors are lowered into heated water, and then the temperature is determined. Next is the calibration of the light sensor. It is allowed to assemble the temperature controller inside the greenhouses. It is placed near a heating device, which can be a stove.

Overview of the thermostat (video)

How to work with a thermostat

Thermoregulators, regardless of whether they are made by hand or purchased in a store, are very similar in principle of operation. Because of this, it is easy to work with them. What characterizes the work with the device?

• A special button helps to scroll through the menu.
• The temperature is controlled manually.
• You can store settings in the machine's memory for quick start-up.
• The use of special buttons allows you to control the operation of the boiler and stove, set the heating characteristics.
• If there is a display with readings, you can find out what the heating is at a given time period.

Among other things, thermostats make it possible to control the boiler for heating the greenhouse.

1. After the controller is powered up, the sensors are polled for real-time information. Then the controller compares the readings and the already recorded information for the day or night and selects the necessary settings for the thermostat.
2. After 5 minutes, the thermostat is activated, and the boiler starts working.
3. If the heating is insufficient, the heater with the pump starts to function. A command is given to increase the fuel supply, which increases heating.

Thermostats are multifunctional. With their help, you can heat the greenhouse and set the required temperature for the air in the building, as well as heat the soil and water.

The controller is able to support optimal conditions environment in any . Some devices turn on and work independently, which is very convenient. Connect them to the controller, heat sensors, stove and boiler. Ultimately, control over temperature regime possible to the fullest.

Making a simple do-it-yourself regulator

You can make a regulator with your own hands from a standard household thermometer. However, it will have to be modified.

• First, disassemble the device, but remember to proceed with caution.
• In the scale, at the location of the area of ​​the required control limit, a hole is made. Its diameter should be less than 2.5 millimeters. A phototransistor is fixed opposite it. Sheet aluminum is taken, a corner is made in which a 2.8 mm hole is drilled. The phototransistor is glued to the "Moment" glue in the socket.
• A corner is fixed below the hole so that when the temperature rises (during the day), the arrow does not have the opportunity to pass the hole. This will prevent the heating from turning on when it is not needed.
• With outer side a 9-volt bulb is installed on the thermometer. A hole is drilled in the body of the thermometer for it. A lens is placed inside between the scale and the light bulb. It is necessary for the device to work accurately.
• The wires from the light bulb are passed through a hole in the housing, and the wires from the phototransistor through a hole in the scale. A common tourniquet is placed in a vinyl chloride tube and fixed with a clamp. A 0.4 mm hole is drilled opposite the bulb.

• In addition to the sensor, the thermostat must have a voltage stabilizer. A photo relay is also required. The stabilizer is powered by a transformer. A modified transistor of the GT109 type serves as a photocell for the photorelay. All you need to do is remove the cap from its body and break off the base terminal.
• A mechanism made from a factory-made relay is used as a load. The work in this case follows the principle of an electromagnet, where the steel anchor goes inside the coil and affects the microswitch, which is fixed with 2 brackets. And the microswitch actuates the electromagnetic starter, through the contacts of which the supply voltage goes to the heating device.
• The photorelay, together with the power subunits, is placed in a housing made of insulating material. A thermometer is attached to it on a special rod. On the front side there is a neon light (it will signal the start of the heating elements) and a toggle switch.
• In order for the regulator to work accurately, it is necessary to achieve a clear focusing of the light coming from the bulb onto the photocell.

How to make a thermostat with your own hands (video)

Thus, despite the complexity of the work, installing a thermostat greatly simplifies maintenance. Cultures receiving optimal microclimate, develop better, which means that the harvest will be much larger.

Temperature controls in individual rooms

Thanks to the Danfoss radiator thermostat, only required amount energy, and the temperature in the room is constantly maintained at the required level. The thermostat measures the room temperature and automatically regulates the heat supply.

It allows to avoid overheating of the premises during the transitional and other periods of the year and to ensure the minimum required level of heating in premises with periodic residence of people (system frost protection).

Short name for radiator thermostatRTD(Radiator Thermostat Danfoss). What is a radiator thermostat?

1 - combination of room temperature sensor and water valve,

2 - independent pressure regulator (works without additional energy source)

3 - a device that constantly maintains a given temperature.



The principle of operation of the radiator thermostat:

The principle of operation is the balance between the force of the medium (in this case: gas) and the force of the pressure spring, the value of which depends on the setting of the head (to the required temperature). Thus, the amount of flow through the valve depends on the head setting and temperature. external environment which is perceived by the sensor.

If the temperature rises, the gas expands and thus slightly closes the valve. If the temperature drops, then the gas is compressed accordingly, which leads to the opening of the valve and the access of the coolant to the heater.

Gas use provided by Danfoss great advantage over other manufacturers: a small value of the time constant, which is expressed in best use free heat through a quick response to changes in room temperature (reaction time).

To date, only Danfoss radiator thermostats use the principle of gas expansion and contraction. The reason is that the use of gas requires very modern technology and, consequently, high quality requirements. However, Danfoss is willing to take on additional costs in order to achieve high quality and competitive products.

The choice of a radiator thermostat depends on the following conditions:

sensor type Y valve location

valve type U radiator size (heat demand), temperature drop per heating element, type of heating system (1- or 2-pipe system)

Why is it necessary to use a radiator thermostat?

1 - because it makes it possible to save thermal energy(15-20%), allows the use of free, “free” heat (solar radiation, additional heat from people and appliances), its payback period< 2 лет.

2 - provides high level comfort in the room.

3 - provides hydraulic balance - it is very important to create a hydraulic balance in the heating system, which means the supply of available heat energy to each consumer according to his needs.

Thermostatic heads RTD (20% heat savings)




Heads for radiator thermostats are available in the following versions:

RTD 3100 / 3102 - standard sensor, built-in or remote, temperature range 6-26°C, limiting and fixing the temperature setting.

RTD 3120 - tamper proof sensor, built-in, temperature range 6 - 26°C, frost protection.

RTD 3150 / 3152 - sensor with maximum temperature limitation, built-in or remote, temperature range 6 - 21 ° C, frost protection, fixing the temperature setting.

row RTD 3160 - element remote control, capillary tube length 2 / 5 / 8 m, maximum temperature 28°C with limitation and fixation of the temperature setting (for radiators and convectors not accessible to the user).

The remote sensor must be used if the built-in sensor will be affected by a draft or hidden behind curtains or decorative grilles.

Fastening the thermostatic head itself to the valve is easily done with a union nut. The head can be secured against unauthorized removal with a screw (ordered separately as an accessory).


Valves RTD-N and RTD-G

When Danfoss began expanding into markets outside Western Europe, then the company's specialists conducted numerous analyzes of water quality in different countries. As a result of this experience, it became clear that in the heating systems of some countries it is often found low quality water. In this regard, a new series of valves has been developed for the markets of Eastern Europe- RTD series.

The materials used in the RTD remain particularly resistant to the poor quality of the water used (compared to valves for Western European markets, we have replaced all tin-bronze parts with more durable brass parts). This means that the service life of the valve is significantly increased, even in difficult conditions Ukraine. We know from experience that average term valve life reaches 20 years.

Type control valvesRTD-N(diameters 10-25 mm) are intended for use in two-pipe pumping systems water heating and are equipped with a device for preliminary (installation) adjustment of their throughput.

In 2 pipe system heating, the addition of water in excess of the calculated volume leads to an increase in heat transfer and an imbalance in the system. The valve presetting feature allows the installer to limit the flow of the valve in such a way that the hydraulic resistance in all radiator circuits is the same and thus regulate the flow rate.

Simple and accurate bandwidth tuning is easily done without additional tool. The number stamped on the setting scale must be aligned with the mark located opposite the valve outlet. The capacity of the valve will change according to the numbers on the setting scale. In the “N” position, the valve is fully open.

Protection against unauthorized change of the setting is provided by a thermostatic element mounted on the valve.

Control valves with increased throughput typeRTD-G(diameters 15-25 mm) are intended for use in pumping single pipe systems ah water heating. They can also be used in two pipe gravity systems. Valves have fixed capacity values ​​depending on the valve diameter.

An example of calculating a radiator thermostat:

Heat demand Q = 2,000 kcal/h

temperature difference D T = 20 ° C

existing pressure loss D P = 0.05 bar

Determine the amount of flow (water flow) through the device:

Water consumption G = 2 000/20 = 100 l/h

Determine the capacity of the valve:


Valve capacity Kv = 0.1/C 0.05 = 0.45 m3/bar



A Kv value of 0.45 m3/h indicates that for the 15 mm RTD-N valve you can select presetting “7” or “N”.

When choosing a radiator thermostat, it is necessary to provide an adjustment in the range from 0.5 ° C to 2 ° C for these dimensions, which will ensure good conditions regulation. In our case, it is necessary to select preset “7” or “N”. However, if there is a risk of polluted water in the heating system, we do not recommend using a preset less than “3”.

Using our data sheet “RTD Radiator Thermostats”, you will be able to select the valve size directly from the diagrams in terms of the pressure drop across the D P valve, or in terms of the flow rate through the G valve. The sizing of the RTD-G valves (for 1-pipe system) is carried out identically.


New construction

In new buildings we recommend using a 2-pipe system with pre-adjustable RTD-N valves to maintain the hydraulic balance in the system, DN 10-25 mm, straight and angle versions.



Reconstruction

The vast majority of old buildings use a 1-pipe system, for which we recommend RTD-G valves with increased capacity (fixed capacities depending on the diameter), DN 15-25 mm, straight and angled versions.

Especially for pre-set RTD-N valves, it is very important to use a filter to prevent obstruction to the normal functioning of the valve.


Balancing (balancing) valves of the ASV series

Since radiator heating systems are dynamic systems(different pressure drops due to reduced heat load), radiator thermostats must be combined with pressure regulators (automatic balancing valves ASV-P for 2-pipe system) and shut-off valve MV-FN.

The ASV series of regulators includes two types of automatic and manual balancing valves:

automatic valve ASV-PV - differential pressure regulator with changeable setting 5 - 25 kPa

valve ASV-P - regulator with a fixed setting of 10 kPa

ASV-M - manual shut-off and measuring valve

ASV-І - shut-off and measuring valve with capacity adjustment

ASV ensures optimal distribution of the heat carrier along the risers of the heating system and the normal functioning of the latter, regardless of pressure fluctuations in the system. They also allow you to close and empty the riser. The maximum working pressure becomes 10 kPa, the maximum working temperature is 120°C.

Styrofoam packaging, in which the valve is transported, can be used as a heat-insulating shell at a heat carrier temperature of up to 80 ° C. At a maximum operating temperature coolant 120 ° C, a special heat-insulating shell is used, which is supplied by an additional order.



Automatic flow controller ASV-Q

For hydraulic balancing of 1-pipe heating systems, automatic flow limiting valves ASV-Q are used - diameters 15, 20, 25 and 32 mm (setting range from 0.1-0.8 m3 / h to 0.5-2.5 m3 /hour). They are used to automatically limit the maximum value of water flow through the riser, regardless of pressure fluctuations and coolant flow in the system and for the optimal distribution of the coolant over the risers of the heating system

These valves are especially useful for balancing heating systems for which there is no data on their hydraulic characteristics. ASV-Q always delivers the flow rate that the valve is set to. When the characteristics of the system change, the controller automatically adjusts.

Installing ASV-Q valves eliminates the traditionally complex adjustment works in new construction and reconstruction of heating systems, including expansion of systems without hydraulic calculation of pipelines.



Application (examples 1 - 2 pipe systems)

When reconstructing a one-pipe system without a bypass (flow system), it is necessary to install radiator thermostats on heat sources (RTD-G and RTD heads) and install a bypass line (bypass), the cross section of which should be one size smaller than the main pipe of the system (bypass in 1/2" for the main in 3/4").

With the help of a bypass, the coolant flow through the heat radiation source is reduced to 35 - 30%, which also depends on the diameter of the main pipes in the system. Studying the heat transfer curve of the radiator of a single-pipe system, we are convinced that a decrease in the coolant flow from 100% even to 30% will lead to a decrease in the heat transfer of the radiator by only 10%.

This means that in the vast majority of cases the installation of a bypass will only have a negligible effect on heat dissipation. In many cases, the dimensions of the heat emitter (radiator, convector) are already chosen with a margin, and therefore the heat emitters can continue to provide the required amount of heat. If the radiator is low-power, then to solve the problem it is necessary:

- Increase the temperature of the coolant

- Increase the performance of the circulation pump

- Enlarge heating surfaces of radiators

-Insulate building envelopes (walls)

High capacity RTD-G valves are used in single-pipe heating systems with circulation pumps and in two-pipe systems ah gravitational (gravitational).

To maintain the hydraulic balance in the heating system, it is necessary to install on each riser automatic regulator flow ASV-Q, which will limit the flow in each riser. In this way the heat will be distributed evenly to all risers, especially in case of variable heat load or if there is insufficient heat supply. The shut-off and measuring valve ASV-M allows you to close each individual riser and, if necessary, drain water from it, while simultaneously measuring the flow through the riser.

Heat emitters (radiators and convectors) can be equipped with radiator thermostats (RTD-G and RTD heads) without any restrictions. The selection of the RTD-G valve is carried out in accordance with the previous example (see also the RTD-G selection example in technical description). In this case, the risers must be equipped with flow restrictors ASV-Q and ASV-M with shut-off and measuring valve.

In the case of a 2-pipe system, the radiators can be equipped with radiator thermostats (RTD-N and RTD sensors) without any restrictions. The selection of the RTD-N valve is made according to the RTD-N examples above. In this case, each riser should be equipped with an ASV-P pressure regulator (and an ASV-M shut-off valve) that will provide a constant D P in each riser, which will compensate for changes in heat load and change in D P. Moreover, reducing the risk noise in radiator thermostats, the differential pressure regulator will thereby ensure their durability


Thus, the issue of temperature control in individual rooms is solved.

Installing meters and believing that savings have been achieved is a delusion. Don't stop there! Having studied the market of energy-saving equipment properly, it comes to the understanding that real savings begin with the installation thermomiser. After all, this device should be used in every heating and hot water supply system! The thermostat is automatic temperature controller, as hot water, and coolant. By equipping your system with a thermomiser, you get the ability to control the climate in any room and enormous savings in hot water or heat carrier consumption, and as a result, money.

How does a thermometer work?

The thermomiser consists of only two components, this is a regulator and electronic device management. The first component, the regulator, is responsible for automatically regulating the temperature of the supply water for the heating or hot water supply system. The second component of the thermomiser is an electronic device that receives data from temperature sensors located inside and outside the room, as well as at the inlet and outlet of the coolant. The received data is processed in accordance with the program algorithm, calculations are made, according to which commands are sent directly to the controller.

What can thermostats do?

By choosing various programs, we have the ability to maintain the set water and heat carrier temperatures, the schedule of the heating system, adjust the temperatures of the return circuit, the heat carrier in the supply pipe according to the deviation from the set internal temperature of the room, adjust when using a timer, separate modes for holidays, weekends and nights and a number of other options. Thermomisers are equipped with rich functionality and saving opportunities, we only need to select the right model, set the right data and set the mode.

An important detail in saving is the equipment of the device outdoor sensor, this is especially true for spring, during sharp changes in temperature at night and day. When monitoring the entire dynamics of differences, we always have the temperature we need inside the room without overspending resources and money.

Which thermostat to choose?

Thermizer should be chosen based on the existing water supply and heating system. Any thermomiser model will effectively save the coolant and create the necessary microclimate in the room. Depending on the type of regulator, some thermomisers can be used in public and administrative buildings, others will be more relevant in open system hot water supply and heating, the third type of thermomisers is better applicable in closed systems with pump mixing, or as an additional option in ventilation systems and air conditioning systems. The most influencing factor in the savings of a thermomiser is the type of regulator.

Our factory manufactures and supplies all the lineup the following temperature controllers:
thermomiser R-2.T, thermomiser R-7.T, thermomiser R-8.T, Teplur control device and other components of ultra-efficient energy saving equipment. You can seek advice on the selection, purchase, delivery, installation and configuration of thermomisers using the contacts indicated on the product page.

How long do thermostats last and how are they used?

In terms of service life, thermomisers are practically eternal, but the quality of the coolant has a direct dependence on the lifetime of the device. Considering the realities, the thermomiser will work freely for 15-20 years. Our factory manufactures regulators from high-quality metals such as stainless steel, brass and cast iron, which has a positive effect on the durability and smooth operation of the devices. This gives significant advantages over imported devices - competitors made of carbon steel, manufactured by Danfoss, etc. The quality of the primary Russian coolant is significantly inferior to the European one, for which imported thermal misers are designed, their operation in domestic systems will be accompanied by many problems.

Thermomisers in maintenance are not whimsical at all. Basically, no Maintenance and not required. It is enough to set up the controller once initially. It is recommended to delegate installation to professionals.

Benefits of installing a thermostat

Often, when the coolant passes through the circuit heating system it does not cool down and has a temperature high enough to be reused. This is exactly what is done with a thermometer. Due to the secondary use of the coolant, we achieve significant savings. Administrative, residential and public buildings can be connected according to this scheme.

For the time when we do not use the premises, for example, on weekends or holidays, you can set minimum temperature coolant on the thermomiser, which will entail a significant reduction in coolant consumption.

Thermomisers also allow you to save thermal energy in production and retail space. For this energy you have to pay a lot of money on the meter. Just imagine what kind of overpayment is received for weekends, holidays, night time and other cases when the premises are not used. For all these cases, you can set up certain modes in the thermomiser controller and not pay extra money for overspending the coolant.

The advantages of thermomisers are expressed not only in money, do not forget about comfort. After all, the possibility of adjusting and maintaining the temperature at the required level is relevant for many rooms of various buildings and areas.

Temperature is an indicator of the thermodynamic state of an object and is used as an output coordinate in the automation of thermal processes. Characteristics of objects in temperature control systems depend on the physical parameters of the process and the design of the apparatus. So general recommendations it is impossible to formulate temperatures for the choice of ACP and a careful analysis of the characteristics of each specific process is required.

Temperature control in engineering systems ah is performed much more often than the regulation of any other parameters. Range controlled temperatures small. lower limit this range is limited minimum value outside air temperature (-40 °C), upper - maximum temperature coolant (+150 °С).

To common features ACP temperature can be attributed to the significant inertia of thermal processes and temperature meters (sensors). Therefore, one of the main tasks in the creation of ACS temperature is to reduce the inertia of the sensors.

Consider, as an example, the characteristics of the most common manometric thermometer in engineering systems in a protective case (Fig. 5.1). block diagram such a thermometer can be represented as a series connection of four thermal containers (Fig. 5.2): a protective cover /, air gap 2 , walls of the thermometer 3 and working fluid 4. If we neglect the thermal resistance of each layer, then the heat balance equation for each element of this device can be written as

G,Cpit, = a n? sjі ( tj _і - tj) - a i2 S i2 (tj -Сн), (5.1)

where Gj- the mass of the cover, air layer, wall and liquid, respectively; Cpj- specific heat capacity; tj- temperature; a,i, and /2 - heat transfer coefficients; S n , S i2 - heat transfer surfaces.

Rice. 5.1. Schematic diagram of a manometric thermometer:

• 1 - protective cover; 2 - air gap; 3 - thermometer wall;
• 4 - working fluid

Rice. 5.2.

As can be seen from equation (5.1), the main directions for reducing the inertia of temperature sensors are;

• increase in heat transfer coefficients from the medium to the cover as a result right choice sensor installation locations; in this case, the velocity of the medium must be maximum; ceteris paribus, it is more preferable to install thermometers in the liquid phase (compared to gaseous), in condensing vapor (compared to condensate), etc.;
• reduction of thermal resistance and thermal capacity of the protective cover as a result of the choice of its material and thickness;
• reduction of the time constant of the air gap due to the use of fillers (liquid, metal chips); for thermocouples, the working junction is soldered to the body of the protective cover;
• selection of the type of primary converter: for example, when choosing, it must be taken into account that a thermocouple in a fast-response design has the smallest inertia, and a manometric thermometer has the largest.

Each temperature ACP in engineering systems is created for a very specific purpose (controlling the temperature of the air in the premises, heat or coolant) and, therefore, is designed to operate in a very small range. In this regard, the conditions for the use of one or another ACP determine the device and design of both the sensor and the temperature controller. For example, in the automation of engineering systems, direct-acting temperature controllers with manometric measuring devices are widely used. So, to regulate the air temperature in the premises of administrative and public buildings when using ejection and fan coils of a three-pipe heating and cooling circuit, a direct-acting regulator is used direct type RTK (Fig. 5.3), which consists of a thermal system and a control valve. The thermal system, which proportionally moves the control valve stem when the temperature of the recirculation air changes at the inlet to the closer, includes a sensitive element, a setting device and an actuator. These three nodes are connected by a capillary tube and represent a single hermetic volume filled with a temperature-sensitive (working) liquid. A three-way control valve controls the supply of hot or cold water to the ejection heat exchanger

Rice. 5.3.

a - regulator; b - control valve; c - thermal system;

• 1 - bellows; 2 - setter; 3 - tuning knob; 4 - frame;
• 5, 6 - regulating bodies respectively hot and cold water; 7 - stock; 8 - actuating mechanism; 9 - sensing element

closer and consists of a body and regulatory bodies. With an increase in air temperature, the working fluid of the thermal system increases its volume and the valve bellows moves the stem and the regulating body, closing the passage of hot water through the valve. With an increase in temperature by 0.5-1 ° C, the regulatory bodies remain motionless (hot and cold water passages are closed), and with more high temperature only the cold water passage opens (the hot water passage remains closed). The set temperature is provided by turning the adjustment knob connected to the bellows, which changes the internal volume of the thermal system. The controller can be set to temperatures ranging from 15 to 30°C.

When controlling the temperature in water and steam heaters and coolers, RT type regulators are used, which differ slightly from RTK type regulators. Their main feature is the combined design of the thermocylinder with the adjuster, as well as the use of a two-seated valve as a regulating body. Such gauge regulators are available in several 40-degree ranges ranging from 20 to 180 °C with nominal diameters from 15 to 80 mm. Due to the presence of a large static error (10 °C) in these controllers, they are not recommended for high-precision temperature control.

Manometric thermosystems are also used in pneumatic P-regulators, which are widely used to control temperature in engineering air conditioning and ventilation systems (Fig. 5.4). Here, when the temperature changes, the pressure in the thermal system changes, which acts through the bellows on the levers that transmit force to the pneumatic relay rod and the membrane. When the current temperature is equal to the set one, the entire system is in equilibrium, both valves of the pneumatic relay, supply and bleed, are closed. When the pressure on the stem increases, the supply valve begins to open. It is supplied with pressure from the mains. compressed air, as a result of which a control pressure is formed in the pneumatic relay, increasing from 0.2 to 1 kgf / cm 2 in proportion to the increase in the temperature of the controlled medium. This pressure activates the actuator.

For automatic control of air temperature in rooms, thermostatic valves of the American company began to be widely used. Honeywell and radiator thermostats (thermostats) RTD, issued by the Moscow branch

Rice. 5.4.

with manometric thermosystem:

• 1 - pneumatic relay rod; 2 - node of unevenness; 3, 9 - levers;
• 4, 7 - screws; 5 - scale; 6 - screw; 8 - spring; 10 - bellows;
• 11 - membrane; 12 - pneumatic relay; 13 - thermal bulb; 14 - feeding

valve; 15 - bleed valve

Danish company Danfoss, the required temperature is set by turning the adjusted handle (head) with a pointer from 6 to 26 °C. Lowering the temperature by 1 °C (for example, from 23 to 22 °C) saves 5-7% of the heat consumed for heating. thermostats RTD allow avoiding overheating of premises during transitional and other periods of the year and provide the minimum required level of heating in premises with periodic residence of people. In addition, radiator thermostats RTD provide hydraulic stability for a two-pipe heating system and the possibility of adjusting and linking it in case of errors during installation and design without using throttle washers and other constructive solutions.

The temperature regulator consists of a control valve (body) and a thermostatic element with a bellows (head). The body and head are connected with a threaded union nut. For ease of installation on the pipeline and connection of the thermostat to the heater, it is equipped with a cap nut with a threaded nipple. The room temperature is maintained by changing the water flow through the heating device (radiator or convector). The change in water flow occurs due to the movement of the valve stem by a bellows filled with a special mixture of gases that change their volume even with a slight change in the temperature of the air surrounding the bellows. The elongation of the bellows with increasing temperature is counteracted by a setting spring, the force of which is adjusted by turning the handle with an indicator of the desired temperature value.

To better suit any heating system, two types of regulator housings are available: RTD-G with low resistance for one-pipe systems and RTD-N with increased resistance for two-pipe systems. Bodies are manufactured for straight and angle valves.

Thermostatic elements of regulators are manufactured in five versions: with built-in sensor; with remote sensor (capillary tube length 2 m); with protection against misuse and theft; with setting range limited to 21 °С. In any version, the thermostatic element ensures that the set temperature range is limited or fixed at the desired room temperature.

Service life of regulators RTD 20-25 years, although the Rossiya Hotel (Moscow) registered a service life of 2000 regulators for more than 30 years.

Control device (weather compensator) ECL(Fig. 5.5) ensures the maintenance of the temperature of the coolant in the supply and return pipelines of the heating system, depending on the outdoor temperature according to the corresponding specific repair and a specific heating schedule object. The device acts on the motorized control valve (if necessary, also on circulation pump) and allows you to perform the following operations:

• maintenance of the calculated heating schedule;
• night drop temperature chart by weekly (interval 2 h) or 24-hour (interval 15 min) programmable clock (in the case of an electronic clock, the interval is 1 min);
• heating of the room within 1 hour after the night temperature decrease;
• connection via relay outputs of a control valve and a pump (or 2 control valves and 2 pumps);

Rice. 5.5. Weather compensator EC/. with setting,

available to the consumer:

1 - programmable clock with the ability to set operating periods for comfort or reduced temperature on a daily or weekly cycle: 2 - parallel movement of the temperature graph in the heating system depending on the outside temperature (heating graph): 3 - operating mode switch; 4 - a place for the instruction manual: 5 - signaling the inclusion, the current mode of operation,

emergency modes;

O - heating is turned off, the temperature is maintained to prevent freezing of the coolant in the heating system;) - operation with a reduced temperature in the heating system; © - automatic switching from mode comfortable temperature to the low temperature mode and back in accordance with the setting on the programmable clock;

O - work without lowering the temperature on a daily or weekly cycle; - manual control: the regulator is off, the circulation pump is always on, the valve is controlled manually

• automatic transition from summer mode in winter and back according to the set outdoor temperature;
• termination of the night temperature decrease when the outside temperatures fall below the set value;
• protection of the system from freezing;
• correction of the heating schedule according to the air temperature in the room;
• switching to manual control of the valve drive;
• maximum and minimum supply water temperature limits and the possibility of fixed or proportional

temperature limitation return water depending on the outdoor temperature;

• self-testing and digital indication of temperature values ​​of all sensors and states of valves and pumps;
• setting the dead zone, proportional band and accumulation time;
• the ability to work on the accumulated over a given period or current temperature values;
• setting the coefficient of thermal stability of the building and setting the influence of the return water temperature deviation on the supply water temperature;
• protection against scale formation when working with gas boiler. In engineering systems automation schemes,

also bimetallic and dilatometric thermostats, in particular electric on-off and pneumatic proportional.

The electric bimetal sensor is mainly intended for on-off temperature control in rooms. The sensitive element of this device is a bimetallic spiral, one end of which is fixed, and the other is free and satisfies moving contacts, closing or opening with a fixed contact, depending on the current and set temperature values. The desired temperature is set by turning the setting dial. Depending on the setting range, the temperature controllers are available in 16 modifications with a total setting range from -30 to + 35 °C, with each controller having a range of 10, 20 and 30 °C. Operation error ±1 °С at the middle mark and up to ±2.5 °С at the extreme marks of the scale.

The pneumatic bimetallic regulator as a transducer-amplifier has a shutter nozzle, which is acted upon by the force of the bimetallic measuring element. These regulators are available in 8 modifications, direct and reverse action with a total setting range from +5 to +30 °C. The setting range of each modification is 10 °С.

Dilatometric regulators are based on the difference in the coefficients of linear expansion of an invar (iron-nickel alloy) rod and a brass or steel tube. These thermostats do not differ in the principle of operation of control devices from similar regulators using a manometric measuring system.