Homemade thermostat for the boiler

In addition to being necessary for comfort, temperature control in your house also reduces energy use and costs. The boiler is the central component of the heating system in many homes, controlling the amount of heat that is distributed throughout the area. Even though they have a lot of advanced features, modern thermostats can occasionally be pricey or not fully customizable to meet your needs. This is where a DIY boiler thermostat comes into play, providing an adaptable and affordable way to control the temperature in your house.

Although making your own thermostat may seem difficult at first, the average do-it-yourself enthusiast can successfully complete the project with the correct supplies and guidance. Through an understanding of the fundamentals of thermostat operation and the parts needed, you can customize a solution to fit your needs and improve the efficiency of your heating system. A DIY thermostat offers control and versatility, whether your goal is to save energy costs, maximize comfort, or just get a kick out of doing something yourself.

Customizing your thermostat to fit your unique heating requirements and home layout is one of the main advantages of building your own thermostat. Preset temperature ranges and settings that may not suit your tastes or way of life are frequently included with commercial thermostats. You can easily modify features like temperature thresholds and scheduling, as well as incorporate extra features like remote access and smart home compatibility, with a DIY thermostat.

Additionally, creating your own thermostat can be an educational and fulfilling experience that teaches you about the inner workings of electronics and heating systems. This project doesn’t require you to be an expert in engineering or programming—a wealth of online tutorials and resources are available to walk you through every step of the procedure. Every step of the process, from choosing the appropriate parts to putting the circuitry together and setting the controls, presents an opportunity for practical education and skill growth.

Thermostat with your own hands: step-by-step instructions for making a homemade device

Many of the practical gadgets that can improve our quality of life are also easily made on our own.

This category includes thermostats, also known as thermoregulators, which are devices that adjust the temperature of their installed environment to turn on and off heating or cooling equipment.

For instance, a device like this could activate the heater in the vegetable storage area located in the basement during extremely cold weather. You will discover from our article which parts work best for this kind of thermostat and how to make one yourself for a refrigerator, heating boiler, and other systems.

Simple thermoregulator with your own hands – scheme

Due to its simplicity, the thermostat is a common device for inexperienced radio amateurs to practice manufacturing. There are many different ways to offer schemes, but the one that uses a comparator—a unique chip—is the most popular.

There are two inputs and one output for this element. The voltage from the temperature sensor is supplied to the second input, and a specific reference voltage that matches the required temperature is supplied to the first.

Thermostat schematic diagram for heated floors

After comparing the incoming data, the comparator produces a signal that opens a transistor or activates a relay based on a predetermined ratio. In this instance, the cooling or heating unit receives current.

Details of the device of the temperature regulator with their own hands

A thermistor, an element whose electrical resistance varies with temperature, typically serves as the temperature sensor. They also use semiconductor elements, such as diodes and transistors, whose properties are also influenced by temperature. In the case of transistors, this results in an increase in collector current, a shift in the operating point, and eventually a failure to respond to an input signal.

However, one major drawback of such sensors is that they are very difficult to calibrate, or "bound," to specific temperature values. As a result, the accuracy of a homemade thermoregulator is far from ideal.

In the meantime, the industry has long since perfected the ability to produce low-cost temperature sensors that are calibrated during the production process.

This includes the National Semiconductor LM335 that we advise you to utilize. This analog temperature sensor only costs $1.00.

The device is oriented for use with household appliances when it reads "three" at the first position of the numeric row in the marking. The LM135 and LM235 variants are intended for use in military and industrial settings, respectively.

With its 16 transistors, this sensor functions as a stabilizer. The temperature affects the voltage used for stabilization.

The dependence is as follows: the output stabilization voltage will be 2.73 V at zero Celsius (273 Kelvin) for every degree on the absolute scale (Kelvin). The sensor is calibrated by the manufacturer at 25C (298K). It can operate between -40 and +100 degrees Celsius.

By building a thermostat using LM335 as a basis, the user can avoid having to experiment until they find the reference voltage at which the device will produce the desired temperature.

It’s calculable with this easy formula:

Where T is the Celsius equivalent of the relevant temperature.

A comparator (the LM311 from the same manufacturer works well), a potentiometer for forming a reference voltage (which sets the necessary temperature), an output device for connecting the load (a relay), indicators, and a power supply unit are also required in addition to the temperature sensor.

An essential component of the autonomous heating system is the thermoregulator. The house’s comfortable temperature will be maintained with the aid of the heating boiler’s thermostat.

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Power supply of the thermoregulator

Resistor R1 and the LM335 temperature sensor are connected in series. Therefore, it is important to choose the resistor’s resistance and the supply voltage so that the temperature sensor’s current value falls between 0.45 and 5 mA.

It is not advisable to exceed this range’s maximum value because overheating will distort the sensor’s characteristics.

The thermoregulator can be powered by a DIY transformer or a conventional 12 V power supply unit.

Switching on the load

You can use an automotive relay as an actuator to supply power to the heater. It is intended to operate at 12 V, with a current of 100 mA passing through the coil at the same time.

Remember that the temperature sensor’s circuit current does not exceed 5 mA, so in order to connect the relay, you must use a transistor with a higher power, such as the KT814.

If a relay with a lower switching current is used, like the SRA-12VDC-L or SRD-12VDC-SL-C, the transistor won’t be required.

How to make a thermoregulator with your own hands: step-by-step instructions

Let’s look at how to create 12 V thermoregulators (thermorelays) using a hand-held air temperature sensor. The device is assembled in the following order:

1. First of all, you need to prepare the case. An old meter, for example, "Granit-1" is suitable.
2. The circuit can be assembled on the board from the same meter. A potentiometer is connected to the direct input of the comparator (marked with a "+" sign) to set the temperature. To the inverse input (sign "-") – LM335 temperature sensor. If the voltage at the direct input is higher than at the inverse input, the comparator output will be set high (one) and the transistor will supply power to the relay and the relay will supply power to the heater. As soon as the voltage at the inverse input is higher than at the direct input, the level at the comparator output will become low (zero) and the relay will switch off.
3. To provide a temperature difference, that is, triggering the thermostat, for example, at 23 degrees, and shutdown – at 25 degrees, it is necessary to create a negative feedback between the output and the direct input of the comparator with the help of a resistor.
4. The transformer for powering the thermoregulator can be made from a coil from an old electric meter of the induction type. There is space for the secondary winding on it. To obtain a voltage of 12 V, it is necessary to wind 540 turns. These can be accommodated if 0.4 mm wire is used.

Basic DIY thermostat

Turning on the heater with the meter terminal block is convenient.

What should be the heater?

The maximum current that the relay’s contacts can handle determines the heater’s power. This value can be as high as 30 x 220 = 6.6 kW if it is, for instance, 30 A (such a current is intended for automotive relays). The switchboard’s wiring and circuit breaker only need to be confirmed to be able to support such a load.

Let’s examine the proper installation procedure for the device.

Where cold air collects in the lower portion of the room is where the thermostat should be placed.

Avoiding thermal interference is crucial as it has the potential to confuse the device.

For instance, keep the thermostat away from electrical equipment that emits heat and from areas with drafts.

Adjusting the thermoregulator

As previously stated, there is no need to modify the thermostat that uses the LM335 sensor. Knowing the voltage that the potentiometer supplies to the comparator’s direct input is sufficient.

A voltmeter can be used to measure it. The formula above is used to determine the necessary voltage value.

In the event that the device must activate, say, at 20 degrees Celsius, then 2.93 V should be used.

The reference voltage needs to be tested experimentally if a different element is used as a temperature sensor. It is required to use a digital thermometer for this purpose, such as the TM-902C. The thermometer and thermoregulator’s sensors can be connected with duct tape and then placed in a temperature-varying environment for precise adjustment.

Thermoregulator made with homemade components

To activate the thermoregulator, slowly turn the potentiometer knob. At this point, you should compare the temperature shown on the digital thermometer’s scale to the thermoregulator’s scale. By splitting the range into equal sections, it is possible to designate intermediate values and define extreme points, such as those for temperatures of 8 and 40 degrees.

In the absence of a digital thermometer, the extreme points can be found by measuring the temperature of boiling water (100 degrees) or water with ice floating in it (0 degrees).

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Is it possible to make your own thermoregulator for heating?

Many install thermostats to save energy costs by 10% to 15% and make operating your autonomous heating system easier. By using this easy technique, you can enjoy uniform heating throughout the room, save energy, and forget about adjusting the heating system.

A thermostat controls the amount of coolant that flows through it, which in turn controls the room’s temperature. They may be mechanical or electrical.

Making a thermoregulator by hand is very expensive and difficult. Moreover, there are plenty of options available in the sanitary goods market to suit every preference, ranging from the most basic mechanical valves to wireless solutions that integrate with programmers’ tasks.

In our piece "Handmade Thermostat for the Boiler," we’ll look at an easy and affordable way to regulate the heating system’s temperature in your house. You can make your own thermostat to control your boiler’s operation and ensure maximum comfort and energy efficiency with just a few simple tools and materials. Gaining more control over your heating system through the use of our step-by-step guide could result in lower energy costs and a smaller environmental impact. This DIY thermostat project has useful advantages for any homeowner, whether they enjoy do-it-yourself projects or want to cut their heating expenses.

New technology

About ten years ago, thermoregulators made their debut on the home market, taking the place of standard taps and valves that merely stopped the coolant’s conditional passage. The drawback of this design is that you can’t permanently regulate the room’s temperature by varying the amount of coolant that enters the radiator. The solid fuel boiler has a very high temperature range and is dependent on the intensity of the combustion reaction if the electric boiler operates in a relatively stable manner. The comfort of the occupants will be in doubt in this situation as the temperatures in the rooms will fluctuate.

Another crucial point is that thermostats, when used in conjunction with a warm floor, are actively introduced for the first time. Warm floors are becoming standard in construction, and a well-designed heating system is a combined system that uses both radiator and heated floors. Simultaneously, the warm floor circuit should have a temperature of 20–25 degrees Celsius, and radiator heating should start at 50 degrees.

With the installation of underfloor heating, thermostats were first actively introduced.

In this scenario, how should one beat, considering that the boiler powers both the heated floor and the radiators? Using a thermostat is the solution. In this instance, turning on a tap won’t fix the issue of the underfloor heating circuit receiving extremely hot water. Installing a thermostat at the floor heating collector’s entrance or using thermostats on each heating circuit are easy solutions for managing the heating distribution.

Principle of operation of the thermostat and its types

The design of the gadget is straightforward:

• a housing for connection to a shut-off valve or a heater;
• sensor (if necessary);
• a head filled with a temperature-responsive substance;
• valve system.

Paraffin was the reacting agent in the past; it is now a liquid or gas. The material inside the head changes as a result of heat, and this causes the flap that controls the coolant flow to open or close mechanically. Additionally, the operating temperature of the valve can be adjusted using the integrated spring. The temperature of the fluid passing through thermoregulators can be used to control them whether they are mounted on the heater or in the boiler room.

When the device is installed, the coolant flow is adjusted to automatically regulate the heater temperature. The temperature only needs to be adjusted once, after which the system will run autonomously without human assistance.

It is important to discuss the various categories of materials that react to heat separately:

1. Paraffin – practically not used now. The main reason is that paraffin is not stable, and such thermo-heads do not work for more than 2-5 years. The principle of operation of the first thermoregulators was based on the fact that the float was above the paraffin, as soon as the temperature in the room rose, it fell due to the resulting plasticity of paraffin, thereby regulating the temperature.
2. Special thermostatic fluid – its disadvantage is the speed of reaction to changes in room temperature from 15 to 40 minutes. Nevertheless, such heads are reasonably priced and allow significant savings on heating costs .
3. Thermostatic gas – the speed of reaction to a change in the temperature in the room – 2-3 minutes, but they have a high cost and remain quite capricious and demanding to themselves.

Installation of the thermoregulator

There are a few guidelines that apply whether you install a factory thermostat or a homemade one:

• For the thermostat to work, it must be installed only in a vertical position;
• Do not cover the thermostat with curtains, clothing or decorative elements;

If you already have radiators installed, moving the radiator mounts or finding a base that is a similar size will make installing the thermostat more difficult. The thermostatic valve’s connection method is identical to that of a tap or valve installation. A "American" connection type is available that interrupts the heating system’s coolant supply.

For heaters made of steel (convectors) or aluminum (bimetal), thermoregulators are mounted at both the side connection and the bottom. Our lives are increasingly integrating wireless networks; for example, thermostats that can be controlled remotely or that can record statistics can be found.

Self-made thermostat

Since there are only 20–30 parts in the entire circuit, the parts for a homemade thermostat don’t cost more than $10. The work is based on the sensor readings, not on any regulating mechanism or rheostat.

An experienced radio amateur can outfit his development with a basic programmer or timer if needed. It should be noted right away that although the price of thermoregulators is continuously declining, independent device manufacture cannot ensure a long-lasting and trouble-free product.

Thermostat for heating boiler (temperature regulator)

The sensible operation of the boiler and home heating system depends on effective heating control. When control elements are used skillfully, the unit’s energy consumption can be decreased and comfortable temperatures can be maintained throughout the house to prevent overheating. and regulates the boiler’s thermostat, also known as the programmer, based on the room’s temperature.

By using this type of automation, energy consumption can be reduced by up to 20%. Additionally, the cost of energy is quite high, and most people would like to cut their expenses.

We take into account the case where the boiler is accurately calculated, the required building insulation is installed, and the heating system operates as intended.

Main types of boilers and temperature regulation

Boilers come in a variety of forms: gas, electric, solid fuel, and liquid fuel.

Worldwide, boilers are widely used. Boilers, imported production, and samples from within the country are all present. Cast iron or steel are the manufacturing materials. Simple to use, affordable, and equipped with a coolant temperature regulation feature. In less expensive models, a unique component called a thermoelement is used to accomplish this purpose.

From a structural perspective, the thermoelement is a metal product whose geometric dimensions change depending on temperature (i.e., how much it heats up). The unique lever that opens and closes the draft flap is then adjusted as a result. An example of such a regulator is seen in the picture:

Example thermoregulator in photo

The combustion process is stronger the more open the damper is, and vice versa. As a result, the thermostat fully regulates the amount of air that enters the closed type combustion chamber. If necessary, the thermostat stops the air supply, causing the combustion process to fade out. More recent models feature controllers that turn on or off a special fan to regulate air flow based on predetermined thermal modes (see photo below):

Temperature-controlled boiler

The most popular and affordable types of operation units are gas boilers. Both single- and double-circuit boilers are available. Single-circuit boilers are solely intended for heating and only contain one heat exchanger. The following figure displays the switching scheme:

Diagram for turning on a boiler with a single circuit

Two-circuit boilers are made to produce hot water and heat using two heat exchangers. The following is a diagram of the boiler switch-on:

Diagram for turning on a boiler with two circuits

Separate regulators for hot water and heating are present in certain boilers.

Electric boilers

A rather popular swap for solid fuel and gas boilers. Many benefits, great efficiency, but a protracted payback time. Similar to gas boilers, the connection is easy, but there is no cold water supply. Both temperature control and overheat prevention are offered.

Boiler timer that is mechanical

There are three ways to turn on the central heating system using an electric boiler’s basic mechanical timer:

1. The boiler is switched off;
2. The boiler supplies warm water;
3. The boiler will turn on and off at the set time.

A large circular dial with a 24-hour scale in the center is typically seen on mechanical timers. You can set the desired time by rotating the dial, then leave it there. At the designated time, the boiler will be turned on. To make adjusting the operation and mode settings simple, a set of 15-minute period tabs are inserted into the exterior. It is possible to perform an emergency readjustment while the boiler is plugged in.

Mechanical timers are simple to use, but if the family is large and bathing is done multiple times a day at different times, the owners may not be satisfied with the boiler’s daily schedule of turning on and off at the same time.

Types of thermostats

Depending on the kinds of functions they perform, they can be split up into multiple groups:

– With just one purpose (maintenance of temperature);

A thermostat with just one purpose

– having a vast array of features (programmable).

Temperature controller with programming

Thermoregulators are classified into two categories based on how they operate: those that communicate with the boiler wirelessly and those that use wires. Put the thermoregulators in a handy location, attach the temperature sensor, link the boiler control system to it, and turn it on.

Room thermostats should not be obscured by furniture or covered by curtains because they require a steady supply of air to function normally. The proper operation of the electric thermostat may be hampered by nearby lights, televisions, and heating appliances.

Programmable room thermostat

With an electronic room thermostat that is programmable, you can easily adjust the temperature to your preferred level and switch between modes at any time. You can program the timer to heat your home differently on the weekends compared to the weekdays. For individuals who work in shifts or part-time, some timers let you customize the settings for each day of the week. Such thermostats are present in a large number of Terneo and ECM models.

Remote-controlled room temperature

With the help of a programmable room thermostat, you can customize the daily heating rates to suit your needs and keep your house at a constant temperature even when the owners are away. Video: Linking a gas boiler and room thermostat

The whole house can typically be controlled with a single programmable room thermostat if the heating system is provided by a boiler with radiators. When the clocks go forward and backward in the spring and fall, or when there is a specific shift in the weather, some templates need to be adjusted. When day and night change, we also advise adjusting the temperature settings.

The following options for this type of climate controller increase its capabilities:

• "Batch" that stops heating for a few hours, then resumes afterward;
• "Override" allows you to temporarily change the programmed temperatures during one of the set up periods;
• "Holiday", increases the heating intensity or decreases it for a certain number of days.

Central thermostat

This thermostat, which is situated some distance from your boiler, usually lets you control the heating in your entire home. While more recent systems typically transmit signals to the device’s command center, older models are wired to the boiler. The newer devices have relatively expensive but effective devices installed, such as domestic AOGVs, Ferroli two-circuit boilers, and Beretta devices.

The most well-known room thermostats for GSM and Protherm brands of two-circuit boilers. Often used with electric boilers or solid fuel units, they feature an integrated dilatometric thermostat for the boiler that can be controlled remotely based on the model.

When necessary, the room thermostat turns off the system’s heating. When the air temperature drops below the thermostat setting, the heating system senses the drop in temperature and activates the heating system; it shuts off when the desired temperature is reached.

1. A thermostat setting of 20° C is recommended;
2. At night, the set temperature should be between 19-21° C.
3. It is desirable that the temperature in the children"s room should be around 22° C.
4. The temperature should not fall below 22°C in a room for the elderly and disabled people.

Generally speaking, the temperature of each room or the entire house is the only microcontroller climate in the heating system. The living room or bedroom, which ought to be the most used areas of the house, is the greatest choice for its placement.

Since room thermostats depend on open airflow to measure temperature, furniture and curtains should not obstruct them. Electric thermostats may experience malfunctions when adjacent appliances are in the way of their proper functioning. These consist of touch switches, lamps, televisions, and nearby boilers that are visible through the wall.

Thermostatic control valves

Thermostatic valves provide a straightforward solution to the coolant temperature control issue by allowing colder and warmer water to mix. Below is a picture of the three-way valve:

Diagram showing how to add a three-way valve to a heating system:

Diagram of the heating system’s three-way valve

Diagram of the piping for a solid fuel boiler using a thermostatic three-way valve:

Diagram of the piping for a solid fuel boiler using a thermostatic three-way valve

Diagram of the gas boiler’s piping system using a three-way thermostat:

Diagram of the gas boiler’s plumbing that uses a three-way thermostatic valve

By adjusting the hot water flow through the radiator, the thermostatic radiator valve lets you regulate the room’s temperature. They don’t control the boiler; they only manage the hot water flow via the radiator. Installing these devices will allow you to customize each room’s required temperature.

It would be a good idea to add this concept to an installation of thermostatic controls. Additionally, these devices require routine performance evaluations and periodic readjustments (every six months when operating modes are changed).

Materials Needed	Instructions
1. Microcontroller (e.g., Arduino)	1. Connect the microcontroller to a power source.
2. Temperature sensor (e.g., DS18B20)	2. Attach the temperature sensor to the microcontroller.
3. Relay module	3. Wire the relay module to the microcontroller.
4. LCD screen (optional)	4. Connect an LCD screen if you want a display.
5. Breadboard and jumper wires	5. Use a breadboard and jumper wires for connections.
6. Enclosure (optional)	6. Put all components in an enclosure for protection.
7. Code for thermostat logic	7. Write or download code for thermostat functionality.
8. Power supply	8. Ensure a stable power supply for the system.

Building your own boiler thermostat can be an enjoyable project that will save you money and give you more options for personalizing your home’s heating system. With a little technical know-how and some basic parts, you can modify the thermostat to suit your unique requirements and tastes.

Being able to precisely control your heating system is one of the main advantages of building your own thermostat. When compared to store-bought options, a DIY thermostat offers more flexibility in terms of scheduling adjustments or maintaining a constant temperature throughout the day.

Building your own thermostat can also be an affordable option, particularly if you already own some of the required parts. With a little ingenuity and resourcefulness, you can find less expensive alternatives or repurpose pre-existing materials to lower the project’s overall cost.

Making your own thermostat also gives you a sense of empowerment and fulfillment. Rather than depending exclusively on off-the-shelf products, you can create a solution that is precisely tailored to meet your needs. This practical method not only reduces costs but also develops a better comprehension of your house’s heating system.

It is imperative to approach this project cautiously and meticulously, though. It takes careful planning and observance of safety procedures to work with electrical components and interface with your boiler. Before taking on a DIY project, make sure you have the abilities and knowledge required to finish it safely.

To sum up, a DIY thermostat for your boiler combines satisfaction, customization, and affordability. You can increase comfort and possibly save money by taking charge of your heating system and customizing it to meet your needs. To ensure success, just keep in mind to put safety and careful planning first.

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