Thermal relay for switching on and off

Comfort and energy efficiency depend on having our homes well-insulated and heated. The thermal relay, a gadget that is essential to this endeavor since it regulates the heating system, is one of the main players. Knowing the importance of thermal relays and how they operate can make it much easier for us to keep our homes comfortable and effective.

For heating systems, a thermal relay essentially serves as a protective switch that turns them on or off automatically based on temperature. This device is especially important in situations where there needs to be constant temperature control, like home heating systems. The relay keeps an eye on the heating apparatus’s temperature in order to avoid overheating or sustain a constant degree of warmth.

Consider the following scenario: a heating system that reaches dangerous temperatures is left on and running without supervision. This can be dangerous in addition to being an energy waste. This is where a thermal relay comes in handy. It detects when the temperature rises above a safe level and turns off the heating system to avoid any possible risks like fires or damage to the equipment.

The idea behind a thermal relay is not too complicated. It is made up of a sensor that monitors temperature variations and a switch mechanism that reacts to them. The relay’s switch is triggered when the temperature rises above a predetermined point, turning off the heating system’s power supply until the temperature returns to a safe level. Because the heating system only runs when necessary, this automated process not only improves safety but also encourages energy efficiency.

Adding a thermal relay to your systems can be a smart decision for homeowners looking to maximize their insulation and heating tactics. This gadget contributes to lower energy consumption and maintenance costs while providing an additional degree of control and security. It also gives peace of mind. A well-managed and effective home heating system depends on your ability to comprehend the function and advantages of a thermal relay, whether you’re planning a new installation or updating an old one.

How to build a thermorelay with temperature control: 2 methods

You can buy or make your own thermorelay with temperature control. Modern man is actively incorporating devices that enable the automation of hot water supply systems, HVAC systems, and heating and ventilation systems into their daily lives. Thermostatic relays are also included in these devices. Read on to learn about the different kinds of temperature control thermorelays that are available today, where thermoregulators can be used, and how to build a device yourself.

What is a temperature-controlled thermostatic valve?

An electromechanical device called a temperature-controlled thermorelay is intended to regulate temperature in a non-aggressive setting. The relay’s ability to open and close the electric circuit contacts in response to variations in the temperature regime allows for temperature regulation through the use of the device.

This enables you to use heating equipment only when necessary.

Thus, depending on the weather, thermorelays equipped with external heat-sensitive sensors can be used to control the heating system’s operation. When the outside temperature falls below the predetermined level, the regulator will activate the heaters.

Furthermore, a thermostat relay can be employed for:

• Control of water heating equipment in autonomous heating and hot water supply systems;
• Autonomous operation of the "warm floor", water heating boiler;
• Automation of air-conditioning systems in greenhouses;
• In automatic heating systems for cellars and other storage and utility rooms.

Thermostats come in various varieties. The devices are essentially distinguished by their designs. Meanwhile, their device hasn’t really changed at all. Two primary components of a thermorelay are a thermoregulator that signals when to turn on or off air conditioning and heating units and a temperature-sensitive sensor. The device’s digital display typically shows information about the set and actual temperature conditions, and the LED indicator indicates whether the relay is in operation.

What is the hysteresis of a thermostat for?

The majority of temperature control devices on the market today can adjust the hysteresis in addition to setting the desired temperature. What does a thermostat’s hysteresis mean? This is the temperature at which the signal exhibits an inverse change. The relay controls whether the connected equipment is turned on or off by virtue of the hysteresis setting.

A hysteresis thermostat’s primary purpose is to switch the connected equipment on and off.

In other words, hysteresis is the variation in temperature between the operating and resting temperatures of equipment used to heat or cool an area.

For instance, if the thermoregulator’s hysteresis is set to 2 °C and its internal temperature is set to 25 °C, the thermorelle will activate the room’s heating system when the outside temperature falls to 23 °C. Boilers that use gas or electricity can be examples of this type of equipment. The thermostat will be triggered less frequently the higher the hysteresis. If saving electricity is the primary reason for installing an automatic thermostat, then this should be considered.

Types of on/off thermostat relays

A traditional on-off thermostat is a small electronic device that is connected to the controlled equipment and wall-mounted in an appropriate spot. The most economical temperature regulator is the one with mechanical control since it is the simplest.

Furthermore, every thermostat is separated into:

1. Programmable control devices. Such regulators are connected to the equipment both wired and wirelessly. Adjustment of the relay is made through a special program or LCD display. Thanks to software it is possible to set the relay to operate at certain times of the day and year.
2. Thermostat relay with GSM wireless programming module. Such devices can be either with one or two temperature sensors.
3. Battery-powered stand-alone regulators. Such installations are most often used to control the operation of household appliances (e.g., refrigerator), incubators.

Utilizing an external sensor, distinguish wireless devices apart. These gadgets are thought to be the most efficient. Because the temperature sensor responds to a change in temperature before it has a chance to influence the room’s temperature, they are known for their quick performance.

How to make a thermorelay with your own hands

You can order something suitable for the thermorelay’s mode of operation online or put it together yourself. Handmade air temperature regulators are typically made to run off of a 12 V battery. A power cable can also be used to supply power to the thermorelay from the electrical wiring.

To become proficient with the thermoregulator, you must first prepare the device’s body and additional tools for use.

A trustworthy thermoregulator with a sensor should be put together as follows:

1. Prepare the device housing. For this purpose, you can choose a case from an old electric meter, circuit breaker.
2. To the input of the comparator (labeled "+") to connect a potentiometer, and the minus inverse input – temperature sensors such as LM335. The scheme of operation of the device is quite simple. When the voltage rises on the direct input, the transistor supplies power to the relay, and it, in turn, to the heater. As soon as the voltage on the inverse input becomes higher than on the direct one, the level on the comparator output will approach zero and the relay will turn off.
3. Create a negative connection between the direct input and the output. This will create the limits of switching on and off the thermoregulator.

To power the thermoregulator, you can extract the coil from an old electromechanical electric meter. It will be necessary to wind 540 turns on the coil in order to achieve the required voltage of 12 V. Copper wire with a minimum diameter of 0.4 mm is the ideal choice.

How to make a thermoregulator for incubator with your own hands

An incubator is a necessary tool for farming that enables you to raise chicks at home. A thermorelay can be used to regulate the incubator’s temperature. You can buy a thermorelay for the incubator or make one yourself using scrap materials.

There are two methods for creating an incubator thermostat:

• Using a stabilizer, a thyristor and 4 diodes with a power of at least 700 watts. Temperature regulation is carried out through a variable resistor with resistance in the range from 30 to 50 kOhm. The temperature sensor in this device will be a transistor installed in a glass tube and placed on a tray with eggs.
• Using a thermostat. To the body of the thermostat with a soldering iron you will need to attach a screw and connect it to the contacts. The rotation of the screw will regulate the temperature indicators.

The second approach is thought to be the most straightforward and practical. Whatever the type of thermorelay, you need to set up the homemade thermoregulator and heat the incubator before laying eggs.

An easy-to-use gadget called a thermorelay with temperature control enables you to program the heating, cooling, and ventilation systems to run automatically. The thermostat allows electrical appliances to be used automatically for their intended purpose, which lowers the amount of electricity used. Selecting a thermostat will be aided by the above suggestions. And in the event that you are unable to locate the ideal gadget, you can always put together a thermoregulator yourself!

Temperature-controllable thermostat relay: thermoregulator in your hands, temperature sensors that turn on and off

Thermorelays with temperature control: applications for thermostats, and DIY methods for creating a thermorelay with a sensor.

In the world of heating and insulating homes, the thermal relay plays a crucial role in managing energy efficiency and safety. Essentially, a thermal relay is a device designed to monitor and control the temperature of electrical components like heating systems or appliances. It works by automatically turning these systems on or off based on temperature thresholds, preventing overheating or potential damage. This technology not only ensures optimal performance and longevity of heating equipment but also enhances safety by preventing fire hazards. By integrating a thermal relay into your home heating system, you can achieve better control over energy usage, reduce the risk of malfunctions, and ultimately create a more comfortable and secure living environment. Whether it"s for electric heaters, boilers, or other heating devices, understanding and utilizing thermal relays can significantly improve the efficiency and safety of your home"s heating and insulation setup.

Thermorelay with your own hands

1. The device and the principle of operation of the thermorelay
2. Typical scheme of thermostat
3. How the ready-made circuit works
4. Simple circuit of the device

In domestic settings, thermostats are used for appliances such as refrigerators and irons. It is frequently necessary to connect warm floors or set a specific temperature in a room. You have two options for this: either use factory-made products, or create a homemade thermorelay with the specifications needed under particular circumstances.

Device and principle of operation of the thermorelay

The most common practice for amateur designs is to use transistors, diodes, or thermistors. The simplest electrical circuit starts with this.

The heating element is turned on and off on a regular basis to maintain the desired temperature. The heating element is disconnected by a comparator device, a compressor, when the temperature reaches the predetermined level. Though it seems straightforward, there are some challenges in actual use.

The construction and regulation of the necessary temperature presents the biggest challenge. The sensor is submerged in a container containing melting ice and boiling water on alternate occasions to determine the characteristic points of the temperature scale. As a result, the boiling point and zero degree temperatures can be calibrated. The thermostat’s necessary intermediate operating temperature is set based on the data that was collected.

It is advised that temperature sensors in the thermo relay circuit be factory calibrated. They are offered as microcontroller-operated sensors. Digital transmission is used to transfer the data. In construction, the LM335 device and its modifications 135 and 235 are most frequently utilized. The device’s designation is indicated by the marking’s first digit. Number 1 sensors are used in the military, number 2 sensors are used in industry, and number 3 sensors are meant for use in home appliances. It is the 335th model that is utilized in the household relay circuit. The temperature range in which the device is intended to operate is -40 to +100 degrees Celsius.

Typical circuit of a thermorelay

The temperature sensor (LM335 or on logi) and the compramator (LM311) form the foundation of the design. An output device to which a heater with a fixed power is connected completes the thermostat circuit. Indicators can be used if necessary, but a power supply unit is required.

Transistors, a relay, a stabilizer, and capacitor C1, which reduces voltage ripples, are parts of a more intricate circuit. To achieve current equalization, a parametric stabilizer is used. In this instance, the device’s power supply can come from any source as long as its parameters fall between 12 and 24 volts for the relay coil. A traditional diode bridge with a capacitor can be used to stabilize the power supply.

How the ready-made circuit works

Transistor assistance is used to turn on the relay, which guarantees that the magnetic starter is activated. The heater has its own two contacts, which it uses to connect to the network. In this instance, the load has no phase remaining after the starter is turned off. It is advised to connect using an RCD if the room has a high level of humidity.

Other than heating elements, 100 W calibration lamps, oil radiators, and built-in fan home heaters are used as heaters. Direct access to live parts must be prohibited.

Checking the quality and accuracy of installation is necessary once the thermostat for manually turning on and off is assembled. Every connection needs to be soldered securely. Following that, the device can be constructed using the predetermined parameters.

Once you’ve put the thermostat together by hand, you should make sure everything is installed correctly. Every connection needs to be soldered securely. The instrument can then be adjusted after that.

Temperature sensors, thermistors, thermo-resistors, thermo-relays.

Temperature sensors are devices that convert temperature readings into different physical characteristics like voltage or resistance.

Thermistors

Temperature sensors known as thermoresistors translate a temperature measurement into resistance. Every conductor has resistance, and resistance varies with temperature. The temperature coefficient of resistance, or TCS, is a measurement that indicates how much resistance changes when temperature changes by 1 0 C. A positive TCS indicates that resistance increases with temperature, while a negative TCS indicates resistance decreases.

Fundamental properties of thermocouples:

-interval of the recorded temperatures;

-maximum power dissipation, here we refer to the thermal characteristic;

NTC, or negative temperature characteristic, is a property of thermosistors. They are composed of ceramics, diamond crystals, and oxides of different metals.

From -40 to 300 0 C, NTC resistors are used as temperature sensors in both industrial and domestic appliances.

Inrush current limitation in a variety of electronic devices, such as switching power supplies, which are present in all mains-powered devices, is another area of application. The thermistor has a resistance of a few ohms and is room temperature when connected to the mains. There is a surge in current while the capacitor is being charged, but the thermistor, whose resistance determines how far the current can go above the limit, prevents it. The thermistor heats up and loses almost all of its resistance when the current flows, but this has no further effect on how the device works.

Thermistors with a positive temperature characteristic are known as Posistors (PTC). All metals, for instance, have a positive PTC, but they are also composed of semiconductor crystals and ceramics.

Positors are employed as temperature sensors as well, but they have other uses as well:

As protective elements in transformers, electric motors and other electronic devices where there is a risk of overheating. For this purpose, the thermistor is connected in series with the load – motor winding or electronic circuit, and the thermistor itself directly into the heating zone – it is glued with thermal adhesive to the winding or clamped with a clamp or simply pressed using thermal paste. At the same time, this overheating protection is quite effective and has no limits of on/off cycle, because there are no opening contacts, just the protective thermistor acquires high resistance and residual current flows through it, the value of which is not dangerous for the load. But the posistor can still be destroyed – at a sudden voltage spike, as the current exceeds the rated current. For example, if instead of 220 V comes 380 V, its resistance will be low enough, as the temperature is normal, but the current that passes through it will exceed the rated current and it will simply burn out, opening the load.

Compressor motor starting is another use. This system is utilized in low-power refrigeration units, such as freezers and refrigerators, that have single-phase electric motors installed with starting windings. Such a scheme, which used two-phase electric motors with operational phase-shifting capacitors, is no longer employed in modern air conditioners.

In this instance, the starting winding is connected via a thermistor to the operating winding, which is connected directly to the mains. The posistor disconnects the starting winding when the compressor is started because the current passing through it heats it up and increases its resistance. As a result, in the event of a brief loss of supply voltage, the compressor might not start because the main winding overheats and the thermistor won’t have time to cool down.

Fluorescent lamp starting schemes make use of PTC resistors.

According to this scheme, when the lamp is turned on, current flows through the low- resistance posistor, heating the posistor and the lamp’s filament. The posistor circuit is then opened, turning on the lamp with heated electrodes. This plan greatly increases the lifespan of energy-efficient lighting.

Liquid level sensors are another application for these thermistors. The control strategy is predicated on the fact that the properties of liquid and air differ; in air, liquid heat capacity and heat transfer are much greater than these values.

Positors are also employed as heating components in the automobile and home appliance industries. These are the very same ceramic heaters that are praised for "not burning oxygen."

Thermocouples are thermal transducer elements that represent a "junction" between metals that are not the same.

The presence of a thermo-EMF in a circuit containing two of these junctions at a temperature differential between them will depend on the type of metals used and the temperature differential between the junctions. The first half of the nineteenth century saw the discovery of the thermoelectric effect.

The uses of thermocouples are extremely diverse and include industry, medicine, and research. Thermocouples are capable of measuring extremely high temperatures, such as liquid steel (1800 0 C).

Copper, chromoly, alumel, platinum, and semiconductor materials are used to make thermocouples.

The opposite effect is also employed: when electric current flows through the circuit, there is a temperature differential between the two junctions. The refrigerators manufactured in the middle of the 20th century used thermocouples, which were semiconductor-based working elements. However, they are no longer in production due to their lower k.ο.д. when compared to compressor refrigerators.

Semiconductor thermosensitive elements

The effect of temperature change at the p-n junction of transistors and diodes is what we are discussing here, despite the fact that thermistors are also composed of semiconductor materials. The temperature coefficient of voltage, or TKN, is a characteristic of these devices. It is the applied voltage changing as the temperature changes. It is always negative and equals roughly 2 mV/0 C in semiconductors.

Temperature sensors based on semiconductors are used to create specialized microcircuits that place multiple crystals at once, as well as stabilization circuits and signal amplifiers with temperature-sensitive elements. These days, numerous manufacturers produce these microcircuits in millions of pieces, making them widely available. Additionally, the customer receives a fully calibrated product that has an output signal that has the necessary error (accuracy) and value. Utilize these chips in a range of devices as temperature sensors.

Semiconductor temperature sensors can also be used as electronic circuit stabilization and compensation components. For instance, strong power elements heat up when current passes through them; this causes the resistance to change, which in turn affects the parameters. To counteract this effect, a thermotransistor is mounted to the body of the element and incorporated into the thermal compensation circuit.

Thermorelays are devices that, upon reaching a predetermined temperature, turn on or off loads by converting thermal energy into mechanical energy that opens or closes electrical contacts.

These products are used in the automation and security of household, industrial, and automotive devices. They are utilized, for instance, in electric fireplaces, heat curtains, and irons. Their affordability and ease of use are their primary advantages.

Thermorelays can be adjusted and are programmed to operate at a specific temperature. With contacts that need to be closed and opened simultaneously, as well as with groups of contacts.

Technical details regarding thermorelays:

-temperature that triggers the relay contacts to open or close

-return temperature, correspondingly, at which the first state is restored

-hysteresis (differential): the variation in temperature between the return and response

-commutated voltage and current; this parameter determines how long a device lasts, so choosing one with a current reserve is wise.

-instrument error, for example, +/- 10%

Bimetallic thermorelays

The actuation of these relays is caused by the dissimilar metals’ varying volumetric expansion, which bends platinum or a bimetal (i.e., two metal) disk. They are safe and fairly easy to use.

These relays come in two varieties: thermal limiters and thermoregulators. While the second type is used for protection and needs to be reset after being triggered by a special button, the first type automatically switches the load on and off and regulates the temperature within predetermined limits.

Thermal sensors of manometer type

These sensors use the effect of different liquids’ volumetric expansion to measure temperature.

For instance, they are used to turn on crankcase drainage and heating in air conditioners and water heaters. They are made up of a liquid-filled bulb that is in contact with the medium and has a metal tube connecting it to the contacts. Alcoholic or ethylene glycol-based mixtures are typically used as working substances.

Electronic thermostats

These are already fairly sophisticated electronic devices that use contactors and electromagnetic relays to switch the load; practically all of the aforementioned types can also be used as temperature sensors. A microcontroller or other specialized electronic circuit processes the signal. These devices can monitor four points, control four loads, and display information on an electronic display. For example, they can have four channels. It is possible to install DIN-rail thermorelays in electrical panels.

Refrigeration technology uses a wide variety of temperature sensors and thermorelays; let’s take a closer look at each type.

Thermostat relays with multiple adjustments. W1209 DC 12 V.

Between -9.9 and +99.9 °C- 0.1 °C

– 1 °C between +100 and +110 and -50 and -10

-0.1 °C, falling between -9.9 and +99.9 °C

-1 °Cbetween -50 and -10 °Cand +100 and +110 °C

Range of hysteresis: 0.1 to 15 °C

Accuracy of hysteresis: 0.1 °C

Update time: half a second.

Direct current (12 V) is the circuit supply voltage (DC12V).

35 mA for static current and 65 mA for current when the relay is closed.

NTC (10K +-0.5%) Thermistor.

50 cm is the sensor’s reach length.

Relay output with one channel and a power of 10 amps

Humidity range: 20% to 85%

48 * 40 * 14 mm in size.

The XH-W1209 digital two-threshold, two-mode, housing-less, 12V power supply temperature controller is made to regulate the temperature of warm floors, swimming pools, freezers, non-freezing gutter systems, and incubators, greenhouses, terrariums, heating systems, and other spaces where the proper air temperature must be maintained. The XH-W1209 is intended to regulate the temperature of the air in heating systems, terrariums, greenhouses, incubators, warm floors, swimming pools, freezers, gutters, etc.

The STM8S003F3P6 microcontroller, which is in charge of the thermo regulator, evaluates the temperature reading from the digital sensor, compares it to the predetermined value, considers the predetermined operating mode, and then determines whether to turn on or off the load based on these factors. Electromagnetic relays are used for switching.

The thermostat is a contact device that uses a relay power element. Thermoregulator with two thresholds: upper and lower (ability to set the upper threshold value and the lower threshold value of the temperature at which the thermoregulator turns on and off).

Three control buttons: -, +, and set.

Set: Chooses the parameter customization and setting mode.

+ and – modifies the parameters’ and settings’ values.

Cooling mode C operates as follows:

Relay contacts are open when the temperature is below the set point; they close when the set point is reached and stay in this state until the temperature falls by the specified hysteresis value (by default, 2ºC).

In mode H (heating), the opposite is true.

The "+" and "-" buttons can be used to adjust the relay switching temperature when the SET button is pressed (if the current temperature is lower than this value, the power terminal contacts are closed).

A heater or cooler needs to be used in tandem with the thermostat.

Press the SET button to set the control temperature. Then, adjust the new temperature with the "+" or "-" buttons, and press the SET button once more.

Holding down the SET button for five seconds is required to enter programming mode. Afterwards, use the "+" or "-" buttons to choose a menu item from the list below. Press and hold the SET button, or hold down the button for ten seconds, to save the settings. Holding down the "+" button will bring you back to the default settings.

User manual, with detailed description of programming modes, in Russian, in the package.

An intriguing feature is that the rate at which temperature readings are updated is based on the rate at which temperatures vary. The indicator updates the readings three times per second for rapid temperature changes and ten times slower for slow temperature changes. To improve reading stability, the outcome is digitally filtered.

The control controller is STM8S003F3P6. Stabilized 5.0 V on AMS1117-5.0 is the reference voltage for the temperature sensor and controller power supply.

The thermostat uses 19 mA of current when the relay is off and 68 mA of current when it is on (at 12 V supply voltage).

• Versatility
• Sensor on the connector included
• Calibration capability
• Small size, weight and cost

• The control relay is 12 V with NO contact, commutates current up to 20 A (14VDC) and up to 5 A (250VAC).
• Sensor type – waterproof: NTC (10K/3435). The temperature sensor is a 10 kOhm thermistor hermetically sealed in a protective metal cap. Temperature sensor wire length 50 cm., But if necessary, it can be extended.
• Measured and controlled temperature range: -50

For home applications, the setpoint and display temperature range of -50ºC to 110ºC is adequate.

This red LED 3-digit indicator measures 22 by 10 mm and indicates temperature in decimal fractions of a degree below -10ºC (to -50ºC) and above 100ºC (to 110ºC). In displays devoid of decimal fractions, the indicator digits t.к. are insufficient. The same principle is used to set the setpoint discreta.

All that the red LED on the board does is replicate the relay’s on/off switch.

Three control buttons: -, +, and set.

Set: Chooses the setpoint and parameter settings mode.

Change the setpoint and parameter values with + and –

It makes more sense to put the + button on the right rather than the center. Additionally, common sense dictates that the magnification should be on the top or right.

Cooling mode C operates as follows:

The relay contacts are open when the temperature is below the setpoint; they close when the setpoint is reached and stay in this position until the temperature falls by the specified hysteresis value, which is currently set to be 2ºC.

It operates the other way around in mode H (heating).

With no contacts and a 12V voltage, the control relay can switch current up to 20A (14VDC) and up to 5A (250VAC).

To slightly broaden the thermostat’s range of use, it would be preferable to install the relay on the connection socket with a switching contact and all three pins.

Encased in a protective metal cap, the temperature sensor is a 10kOhm thermistor that is hermetically sealed. The stated 50cm (or 30cm) of cable can be extended if needed.

Setting a parameter while decoding:

-50°C to 110°C setpoint temperature; default is 28°C

– P1 switching hysteresis: 2.0ºC by default, 0.1 – 15.0ºC

When an actuator and relay are non-symmetrical (i.e., not symmetrical with respect to the setpoint), the accuracy of temperature maintenance is compromised.

The default temperature of P2 is 110ºC, with a maximum setpoint of -45ºC.

Makes it possible to reduce the setpoint range from above

– P3 minimum setpoint temperature, default: -50ºC; range: -50ºC to 105ºC.

Makes it possible to reduce the setpoint range from below

– P4 temperature correction (measured): -7.0ºC to 7.0ºC; default: 0.0ºC

Enables easy calibration to increase the precision of measurements (only characteristic shift).

– P5 reaction time in minutes 0–10min, with a default of 0min

It is occasionally essential to postpone the actuator’s operation; this is especially true for compressors in refrigerators.

– P6 limit of the temperature displayed, by default OFF, from above (overheating) 0°C to 110°C

Ideally, you should avoid touching it needlessly. Holding down the + and – buttons is required to reset the settings to the default state in the event of an incorrect setting, which will result in the display continuously showing "-" in any mode.

– The default operation mode is C for the cooler and H for the heater.

Actually, it just flips the logic of the thermostat.

After turning off, all settings are preserved.

Simple users do not require additional complex settings such as PID, slope, processing, or signaling, even though they are not detected.

LLL is displayed when the temperature drops below -50ºC or when the sensor is turned off.

The display will read HHH if the temperature is higher than 110ºC or if the sensor is shorted.

One noteworthy characteristic is that the rate at which the temperature changes determines how quickly the temperature readings are updated. The temperature transmitter does not need to be connected to the AC mains because the indicator updates three times per second during rapid temperature changes and approximately ten times slower during slow temperature changes. To improve the stability of the readings, a digital filter is applied to the result.

The claimed measurement accuracy is 0.1ºC, but a 10-bit ADC does not allow such luxury and a conventional nonlinear thermistor cannot achieve this without individual calibration by multiple points, which 100% did not do. An accuracy of 1ºC can be anticipated at most.

The thermostat’s actual circuit

The control controller STM8S003F3P6

5.0V on AMS1117-5.0 is the stabilized reference voltage for the temperature sensor and the controller supply.

Thermostat current consumption when the relay is disabled is 19 mA, and when the relay is turned on, it is 68 mA (at 12.5 V supply voltage).

Connecting a supply voltage lower than 12V, or к, is not recommended. The voltage applied to the relay is 1.5 volts lower than the supply voltage. It is preferable if it were slightly higher (13–14V).

The indicator’s current limiting resistors are located in the discharge circuit rather than the segment circuit, which causes a variation in brightness based on the quantity of burning segments. It is noticeable, but it does not interfere with regular operation.

The four-pin RESET input is exposed on the programming pins and only has an internal high impedance pull-up of 0.1 mA. Occasionally, the controller will mistakenly reset itself in response to a strong spark noise in the vicinity—even from a spark within the relay—or when it comes into contact with the contact by accident.

Easily fixed by connecting a 0.1μF blocking capacitor to the common wire.

On two reference points, verification and calibration were performed using traditional methods. Between 0 and 100 degrees Celsius

It was +1ºC in water that had melted ice.

The temperature in a boiling kettle was recorded at 101ºC.

The water with melting ice showed -0.1 +0.1ºC after entering the correction of -1.0ºC, which I was quite satisfied with.

Normal boiling water temperature was 100ºC.

The purpose of the XH-W1209 digital two-threshold, two-mode, 12V power supply temperature regulator is to maintain the necessary air temperature.

Temperature Range	Switching Action
Below 40°F (4°C)	Heating System On
Above 60°F (15.5°C)	Heating System Off

For comfort and energy conservation, it is essential that our homes have effective insulation and heating systems. The thermal relay, a device made to control when heating systems turn on and off based on temperature settings, is one important part that helps with this effort.

The thermal relay operates by keeping an eye on the ambient temperature in which it is placed. The relay turns on the heating system when the outside temperature drops below a predetermined point, indicating that heating is necessary. The relay then turns off the heating when the required temperature is reached in order to avoid overheating and wasteful energy use.

There are various advantages to this automated procedure. First, it makes sure that, in the absence of human intervention, the indoor environment always stays comfortable. By allowing homeowners to select their preferred temperature range, the thermal relay optimizes energy use and lowers utility costs.

Thermal relays also help heating systems last longer and operate more efficiently. These devices contribute to extending the life of heating equipment and lowering the likelihood of malfunctions or breakdowns by preventing overheating and continuous operation.

All things considered, adding a thermal relay to a house’s heating system is a wise investment for anyone trying to increase comfort and energy efficiency. These gadgets support sustainability and financial savings while offering a practical and efficient way to regulate indoor temperature. Homeowners can attain ideal thermal comfort with minimal effort and environmental impact by utilizing automation and smart technology.

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