How to regulate the temperature of the radiator: an overview of modern thermostatic devices

Types of thermal heads and the principle of their operation

Thermoheads are shut-off and control valves.

There are three types of thermostatic heads:

• manual;
• mechanical;
• electronic.

The functions are the same in all, but the implementation methods differ. Depending on the last parameter, they have different capabilities.

What are manual thermal heads?

By design, thermostatic heads duplicate a standard faucet.By turning the regulator, you can adjust the volume of coolant transported through the pipeline.

By setting the thermostat just 1° lower, you can save 6% per year on your annual electricity bill

They are mounted instead of ball valves on opposite sides of the radiator. They are reliable and inexpensive, but they will have to be controlled manually, and turning the valve each time, relying solely on your feelings, is not very comfortable. Basically, such thermal heads are installed on cast-iron batteries.

Switching the valve stem several times a day will loosen the valve handwheel. As a result, the thermal head will quickly fail.

Features of mechanical thermal heads

Mechanical type thermal heads have a more complex design and they maintain the set temperature in automatic mode.

At the heart of the device is a bellows in the form of a small flexible cylinder. Inside it is a temperature agent in liquid or gaseous form. As a rule, it has a high value of the coefficient of thermal expansion.

As soon as the set temperature indicator exceeds the norm, under the influence of the internal environment, which has greatly increased in volume, the rod begins to move.

As a result, the cross section of the passage channel of the thermal head narrows. In this case, the throughput of the battery decreases, and, consequently, the temperature of the coolant to the set parameters.

As the liquid or gas in the bellows cools, the cylinder loses its volume. The rod rises, increasing the dose of coolant passing through the radiator. The latter gradually warms up, the balance of the system is restored and everything starts all over again.

A positive result will be only when there are thermostats in all rooms and on each radiator.

Liquid-filled bellows devices are more popular. Although gases have a faster reaction, the technology for their production is rather complicated, and the difference in measurement accuracy is only 0.5%.

A mechanical regulator is more convenient to use than a manual one. He is fully responsible for the microclimate in the room. There are many models of such a thermal valve that differ from each other in the way the signal is given.

The thermostatic head is mounted so that it is oriented towards the room. This will enhance temperature measurement accuracy.

If there are no conditions for such an installation, mount thermostat with remote sensor. It is connected to the thermal head by a capillary tube with a length of 2 to 3 m.

The expediency of using a remote sensor is due to the following circumstances:

1. The heater is placed in a niche.
2. The radiator has a dimension in depth of 160 mm.
3. The thermal head is hidden behind the blinds.
4. The large width of the window sill above the radiator, despite the fact that the distance between it and the top of the battery is less than 100 mm.
5. The balancing device is located vertically.

All manipulations with the radiator will be performed with a focus on the temperature in the room.

What is the difference between electronic thermal heads?

Since, in addition to electronics, such a thermostat contains batteries (2 pcs.), It is larger than the previous ones in size. The stem here moves under the influence of the microprocessor.

These devices have a wide range of additional functions. So, they can set the temperature by the hour - at night it will be cooler in the room, and by morning the temperature will rise.

It is possible to program temperature indicators for individual days of the week. Without reducing the level of comfort, you can significantly save on heating your home.

Although the batteries have enough charge to last for several years, they still need to be monitored. But the main disadvantage is not this, but the high price of electronic thermal heads.

The photo shows a thermal head with a remote version of the sensor. It limits the temperature to the set value. Adjustment possible from 60 to 90°

If a decorative screen is installed on the radiator, the thermal head will be useless. In this case, you will need a regulator with a sensor that records the outside temperature.

Valve installation

Temperature controllers can be installed both at the radiator inlet and at the outlet - this will not affect the efficiency of the device in any way. However, before installing the device, you need to find out how the thermostat works on the battery, and study a number of parameters that affect the functionality and performance of the device.

In particular, during installation, you need to think about at what height the device will be located - this parameter is one of the main characteristics of thermostats. All devices of this type are configured at the factory, and this process is carried out with the expectation that the thermostat will be connected to the upper radiator manifold - and this is a height of about 60-80 cm above the floor.

Of course, this option cannot be used if the radiators were installed using the bottom connection method.To solve this problem, there are three solutions - find a faucet with a bottom-mounted thermostat for radiators, install a remote sensor, or independently adjust the thermostatic head. Setting up the regulator is not particularly difficult, and the technology for this process is usually described in the documentation attached to the device.

A special point is the question of how to properly install a thermostat on a battery in an apartment building. With single-pipe wiring, a mandatory element of the system will be a bypass - a structural element located before the battery and connecting the two pipes to each other. In the absence of a bypass, a very unpleasant moment will turn out - the thermostat will change the temperature of the entire riser. Of course, this is not the goal pursued by the installation of a thermostat, and the amount of a possible fine for such an impact on heating is very significant.

Options for adjusting a heating radiator with a thermal head

Adjustment can be of two types: quantitative and qualitative.

The principle of the first method is to change the temperature by changing the amount of coolant passing through the radiator.

The second method involves changing the temperature of the water directly in the system. To do this, a mixing unit with a siphon filled with a temperature-sensitive medium is installed in the boiler room. This medium may be liquid or gas-filled.

The variant with a liquid medium is easy to manufacture, but is slower than the gas one.The essence of both options is as follows: when heated, the working medium expands, which leads to stretching of the siphon. As a result, a special cone inside it moves and reduces the size of the valve section. This leads to a reduction in the flow rate of the coolant. At indoor air cooling process runs in reverse.

Customization Features

In order for the thermostatic head valve for the radiator to function correctly, it must be pre-configured. It is required to turn on the heating in the room and close the doors and windows. A thermometer is placed at a certain point, after which the settings are made. The device configuration scheme is as follows:

• Turn the thermal head to the left until it stops. This will open the flow of the coolant.
• Expecting a temperature rise of 5-6°C compared to that which was in the room.
• Turn all the way to the right.
• Waiting for the temperature to drop to the original. Gradual opening of the valve. Stop rotation in case of positive noise or heating of the radiator.

The last position set is optimal and corresponds to a comfortable temperature.

2 ways to adjust heating systems

Essentially, there are two methods for adjusting the temperature.

1. Quantitative. This is a method of changing the speed of movement of heated water using special valves or a circulation pump. In fact, we limit the supply of coolant to the system through heating equipment.

The simplest example of the implementation of this method is to change the speed of the pump. The colder, the harder the pump works and the faster it moves the coolant through the heating system.

1. Qualitative.This method involves adjusting the temperature of the entire system on the heating device (on the boiler, etc.)

The principle of operation of the thermal head for a heating radiator

The task of the thermostat is to control the heating of the battery when the air temperature in the room changes.

The principle of operation of the thermal head:

1. Heated air acts on the composition, the expansion of the bellows begins.
2. Due to the corrugated structure, the capacity itself also increases in volume.
3. The expansion drives the rod, which gradually limits the passage of the coolant to the radiator.
4. The throughput decreases, the temperature of the heating radiator drops.
5. Heating is weakened, the air cools.
6. Cooling causes the bellows to contract, returning the stem to its original position.
7. The coolant supply is resumed with the same force.

Types of thermal heads

1. With internal thermocouple.
2. With remote temperature sensor.
3. With external regulator.
4. Electronic (programmable).
5. Anti-vandal.

Conventional thermostat for heating radiators with an internal sensor is accepted for installation if it is possible to position its axis horizontally so that the room air freely flows around the body of the device, as shown in the figure:

If horizontal mounting of the head is not possible, then it is better to purchase a remote temperature sensor for it complete with a capillary tube 2 m long. It is at this distance from the radiator that this device can be placed by attaching it to the wall:

In addition to vertical mounting, there are other objective reasons for buying a remote sensor:

• heating radiators with a temperature controller are located behind thick curtains;
• in the immediate vicinity of the thermal head there are pipes with hot water or there is another heat source;
• the battery is under a wide window sill;
• the internal thermoelement enters the draft zone.

In rooms with high interior requirements, batteries are often hidden under decorative screens made of various materials. In such cases, the thermostat that has fallen under the casing registers the temperature of the hot air accumulating in the upper zone and can completely block the coolant. Moreover, access to head control is completely closed. In this situation, the choice should be made in favor of an external regulator combined with a sensor. Options for its placement are shown in the figure:

Electronic thermostats with a display also come in two types: with built-in and removable control unit. The latter differs in that the electronic unit is disconnected from the thermal head, after which it continues to function normally. The purpose of such devices is to adjust the temperature in the room according to the time of day in accordance with the program. This allows you to reduce the heating output during working hours when no one is at home and in other similar cases, which leads to additional energy savings.

Servo motor control using AVR ATmega16

Like a stepper motor, the servo motor does not need any external driver such as ULN2003 or L293D. To control it, you need only a PWM modulation signal, which is easy to generate using an AVR family microcontroller. The torque of the servo motor used in our project is 2.5 kg/cm, so if you need more torque, you will need to use a different servo motor.

In the general principles of operation of servomotors, we have already found out that the servomotor expects a pulse to arrive every 20 ms, and the angle of rotation of the servomotor will depend on the duration of the positive pulse.

To generate the pulses we need, we will use Timer 1 of the Atmega16 microcontroller. The microcontroller is capable of operating at a frequency of 16 MHz, but we will use a frequency of 1 MHz, since in our project it will be enough for us in order for the microcontroller to cope with the functions assigned to it. We set the prescaler to 1, that is, we get a scale of 1 MHz / 1 = 1 MHz. Timer 1 will be used in fast PWM mode (that is, Fast PWM Mode), that is, in mode 14 (Mode 14). You can use various timer modes to generate the pulse sequence you need. You can find more information about this in the Atmega16 Official Datasheet.

To use Timer 1 in fast PWM mode, we need the TOP value of the ICR1 register (Input Capture Register1). You can find the TOP value using the following formula:

fpwm = fcpu / n x (1 + TOP) This expression can be simplified to the following:

TOP = (fcpu / (fpwm x n)) - 1 where N = prescaler division factor fcpu = processor frequency fpwm = servomotor input pulse frequency, which is 50 Hz

That is, we must substitute the following values ​​of variables into the above formula: N = 1, fcpu = 1MHz, fpwm = 50Hz.

Substituting all this, we get ICR1 = 1999.

This means that in order to reach the maximum level, i.e. 1800 (rotation of the servomotor axis by 180 degrees), it is necessary that ICR1 = 1999.

For a frequency of 16 MHz and a prescaler division factor of 16, we get ICR1 = 4999.

Rules for choosing a thermostatic head

It is necessary to choose a device taking into account the characteristics of the heating system and its installation. Based on this, temperature control is used valve and thermostatic head for radiators. At the same time, they can be combined in different ways.

For example, for single-pipe systems, it is better to use valves with high capacity. Similar elements are suitable for two-pipe systems with natural circulation of the working medium. For two-pipe systems with forced movement of the coolant, the best option would be to install a thermal head on radiators, which allows you to adjust the throughput.

The choice of a thermal head for a radiator should also be approached responsibly. The most common options are:

• With thermoelement installed inside.
• Programmable.
• With external temperature sensor.
• Anti-vandal.
• With external regulator.

The classic option can be called a thermostat, which has an internal sensor, and is located horizontally. It is not recommended to connect the thermal head to the radiator in a vertical position. In this case, the rising heat can cause the thermostat to work incorrectly.

If it is not possible to install the thermal head horizontally on a heating radiator, then an external sensor with a special capillary tube is additionally mounted.

Valve principle

The valve with a thermal head is designed to maintain the set temperature offline.The device works on the principle of compression-expansion of a gas or liquid, depending on the environment. The thermostat can be built-in or placed remotely.

The thermostatic valve has a bellows - a corrugated movable container, which is filled with a temperature-sensitive agent. When the ambient air is heated, the agent increases in volume and presses on the shut-off cone of the valve, initiating its closure. During cooling, the reverse process occurs - the agent cools, the bellows decreases in volume and the valve opens.

A distinction is made between gas and liquid bellows. Gas agents are more sensitive to environmental changes, but are more expensive and more difficult to manufacture. Liquid ones are less sensitive, but cheaper. The difference in temperature control accuracy is about 0.5 degrees, which is not significant.

How to regulate heating batteries

To understand how the temperature is adjusted, let's remember how a heating radiator works. It is a labyrinth of pipes with different types of fins to increase heat transfer. Hot water enters the radiator inlet, passing through the labyrinth, it heats the metal. This, in turn, heats up the surrounding air. Due to the fact that on modern radiators the fins have a special shape that improves air movement (convection), hot air spreads very quickly. With active heating, a noticeable flow of heat comes from the radiators.

This battery is very hot. In this case, the regulator must be installed

From all this it follows that by changing the amount of coolant passing through the battery, it is possible to change the temperature in the room (within certain limits).This is what the corresponding fittings do - control valves and thermostats.

We must say right away that no regulators can increase heat transfer. They just lower it. If the room is hot - put it on, if it's cold - this is not your option.

How effectively the temperature of the batteries changes depends, firstly, on how the system is designed, whether there is a power reserve for heating devices, and secondly, on how correctly the regulators themselves are selected and installed. A significant role is played by the inertia of the system as a whole, and the heating devices themselves. For example, aluminum heats up and cools down quickly, while cast iron, which has a large mass, changes temperature very slowly. So with cast iron there is no point in changing something: it is too long to wait for the result.

Options for connecting and installing control valves. But in order to be able to repair the radiator without stopping the system, a ball valve must be installed before the regulator (click on the picture to increase its size)

2 How to set up heating in a private house features and nuances

The heating networks of private houses and dwellings in apartment buildings differ greatly. In a separate residential building, only internal factors can affect the operation of heat supply - problems of autonomous heating, but not breakdowns in the general system. Most often, overlays occur due to the boiler, the operation of which is affected by its power and the type of fuel used.

Heating setting

The possibilities and methods of adjusting home heating depend on several factors, the most significant of which are the following:

1. 1. Material and pipe diameter.The larger the cross section of the pipeline, the faster the heating and expansion of the coolant.
2. 2. Features of radiators. It is possible to regulate radiators normally only if they are properly connected to the pipes. With proper installation during operation of the system, it will be possible to control the speed and volume of water passing through the device.
3. 3. The presence of mixing units. Mixing units in two-pipe systems allow you to reduce the temperature of the coolant by mixing cold and hot water flows.

The installation of mechanisms that allow you to comfortably and sensitively regulate the pressure and temperature in the system must be provided for at the design stages of a new autonomous communication. If such equipment is installed without preliminary calculations in an already functioning system, its efficiency can be significantly reduced.

Mounting

The servo is installed on the finished manifold assembly according to the following scheme:

• The device is mounted in any position, regardless of whether it is normally closed, open or universal. But before the first power-up, the drive must be in the open state.
• Check valve and actuator compatibility using a template. It can be found on the device box.
• The threaded adapter (included) is mounted on the valve. Correct installation is confirmed by snapping the latch.

READ MORE: How to deal with collectors

No additional tools are required to mount the drive. Also, in a threaded connection, there is no need to use any sealing materials. The electrical connection of the drive must be carried out according to the scheme provided by the manufacturer.It can be found in the user manual. To dismantle the servo drive, it is necessary to press on its body from the side and pull it up. This will disconnect the device from the adapter.

Scheme of equipment for underfloor heating

How to increase the heat dissipation of batteries

Whether it is possible to increase the heat transfer of the radiator depends on how it was calculated, and whether there is a power reserve. If the radiator simply cannot produce more heat, then any means of adjustment will not help here. But you can try to change the situation in one of the following ways:

• First of all, check for clogged filters and pipes. Blockages are not only found in old houses. They are more often observed in new ones: during installation, various kinds of construction debris enter the system, which, when the system starts up, clogs the devices. If the cleaning did not give results, we proceed to drastic measures.
• Increase the coolant temperature. This is possible in individual heating, but it is very difficult, rather impossible, with centralized heating.

The main disadvantage of regulated systems is that they require a certain power reserve for all devices. And these are additional funds: each section costs money. But it's not a pity to pay for comfort. If your room is hot, life is not a joy, just like in a cold one. And control valves are a universal way out.

There are many devices that can change the amount of coolant flowing through the heater (radiator, register). There are very inexpensive options, there are those that have a decent cost. Available with manual adjustment, automatic or electronic. Let's start with the cheapest.

Types of thermostatic valves for heating radiators

Three types of thermostatic heads can be used in thermostats:

• manual;
• Mechanical;
• Electronic.

Any heat regulator on the battery is used to solve the same problems, but there are quite a few differences in their use, so it’s worth considering each of them in more detail and figuring out how to reduce the heating battery using one or another device.

Hand heads

Thermostatic heads with manual control, according to the principle of operation, completely repeat a conventional tap - turning the regulator directly affects the amount of coolant passing through the device. As a rule, such regulators are installed on both sides of the radiator instead of ball valves. Change of temperature of the heat carrier is carried out manually.

Manual thermostatic heads are the simplest and most reliable devices, distinguished primarily by their low cost. There is only one drawback - you have to manually adjust the thermostatic radiator valve, focusing only on sensations.

Servo connection

Before starting the installation, it is necessary to establish with which thermostat the servomotor will work. If only one water circuit is controlled by the thermostat, a direct connection is established between both devices by means of conductors.

If the so-called multi-zone thermostat is used, which controls several sections at once, then its connection with each servomotor is carried out through a special underfloor heating switch. With its help, various devices are connected and interconnected in a single circuit.

The switch performs not only a connecting and distributing function, but also serves as a fuse.If the position of all shut-off valves is closed, the switch will automatically turn off the power to the circulation pump. This is especially convenient when an autonomous automated gas boiler takes part in the operation of underfloor heating.

Water heated floor is a new and modern type of heating. This heating system is installed in various premises of both residential and domestic purposes.

Water heated floors are a rather complex heating system, which consists not only of the heating elements of the pipes.

It includes the most important distribution body - a collector, which in turn is also equipped with a number of important devices, one of which is a servo drive for underfloor heating.