Single-stage, two-stage and modulating burners for heating boilers. Review.
When choosing burners, consumers face a difficult task– which burner to choose . This choice allows them to make a small comparison of burners from different manufacturers by type of regulation and level of automation of the burner device.
We invite you to familiarize yourself with the opinion of our company’s specialists, based on experience in the use of combined, liquid fuel and gas burners Weishaupt, Elco, Cib Unigas and Baltur.
Let's determine the basic requirements for burners, depending on the application. Depending on the area of application, burners can be divided into groups.
Group 1. Burners for individual heating systems (in this group we include burners with a power of up to 500 - 600 kW, which are installed in boiler rooms of private houses, small industrial and commercial and administrative buildings).
When choosing burners for this group of consumers, it is necessary to take into account the buyer’s wishes in the level of automation of an individual boiler room:
· if you do not have high technical requirements for the installed equipment and want to have a reliable boiler room that does not require large initial financial investments, then you can opt for burners with single-stage, two-stage operating modes;
· if as a result you want to build a heating system with a high level of automation, weather-dependent regulation, as well as low fuel and energy consumption, then it is better for you to use modulating burners or burners with smooth two-stage regulation, which will provide the ability to program power and a wide operating range of burner control.
Group 2. Burners for large heating systems residential complexes (in this group we include burners with a power of more than 600 kW for the needs of housing and communal services, central heating, as well as for heat supply of large industrial and commercial and administrative buildings).
· Smooth two-stage or modulating burners are ideal for this group. This is due to: the high power of boiler houses, the customer’s desire to build a boiler house with a high level of automation, the desire to ensure the lowest possible fuel and electricity consumption (use frequency control of fan power), as well as to use equipment for automatic regulation for residual oxygen in flue gases (oxygen regulation).
Group 3. Burners for use on technological equipment (this group can include burners of any power, depending on the power of the process equipment).
· Preferred for this group modulating burners. The choice of these burners is determined not so much by the wishes of the customer, but by the technological requirements of production. For example: for some production processes it is required to maintain a strictly defined temperature schedule and prevent temperature changes, otherwise this may lead to a violation technological process, product damage and, as a result, significant financial losses. Burners with step control can also be used in process plants, but only in cases where minor temperature fluctuations are acceptable and do not entail negative consequences.
Brief description of the operating principle of burners with different types regulation.
Single stage burners They operate only in one power range, they operate in a mode that is difficult for the boiler. When single-stage burners operate, frequent switching on and off of the burner occurs, which is controlled by the automatic control of the boiler unit.
Two stage burners , as the name suggests, have two power levels. The first stage typically provides 40% of the power, and the second 100%. The transition from the first stage to the second occurs depending on the controlled boiler parameter (coolant temperature or steam pressure), the on/off modes depend on the boiler automation.
Smoothly- two-stage burners allow for a smooth transition from the first stage to the second. This is a cross between a two-stage and modulating burner.
Modulating burners heat the boiler continuously, increasing or decreasing power as necessary. The range of combustion mode changes is from 10 to 100% of the rated power.
Modulating burners are divided into three types according to the operating principle of modulating devices:
1. burners with a mechanical modulation system;
2. burners with pneumatic modulation system;
3. burners with electronic modulation.
Unlike burners with mechanical and pneumatic modulation, burners with electronic modulation allow for the highest possible control accuracy, since mechanical errors in the operation of burner devices are eliminated.
Price advantages and disadvantages
Of course, modulating burners are more expensive than stepped models, but they have a number of advantages over them. The mechanism for smooth power control allows you to reduce the cycle of switching on and off boilers to a minimum, which significantly reduces mechanical stress on the walls and components of the boiler, which means it prolongs its “life”. Fuel savings are at least 5%, and with proper tuning you can achieve 15% or more. And finally, installing modulating burners does not require replacing expensive boilers if they are functioning properly, while increasing the efficiency of the boiler.
Against the background of the disadvantages of stepped burners, the advantages of modulating burners are obvious. The only factor forcing managers to choose step models is their more low price. But savings of this kind are deceptive: wouldn’t it be better to spend a large amount for more advanced, economical and environmentally friendly burners? Moreover, the costs will pay off in the next few years!
Many buyers understand the benefits of using modulating burners, and now they only have to choose the necessary models. Which manufacturers are best to contact? Even with a superficial study of prices for imported and domestic burners, it is clear that the difference is quite significant. Some models from foreign manufacturers are more expensive than products Russian production more than twice.
A detailed analysis of the market for burner manufacturers shows that Russian equipment is significantly inferior to imported analogues in terms of automation level. In order to achieve high level automation of Russian-made burners, it is necessary to invest quite a bit Money for the purchase of the necessary automation systems and installation and commissioning of equipment. Based on the results of all the work, it turns out that the cost of retrofitted Russian-made burners is close to the cost of imported burners. But at the same time, you will not have a 100% guarantee that a fully equipped Russian burner will provide you with the desired result.
Conclusion of our experts
Choosing the right burner is an important step in the construction or modernization of a boiler room. The further operation of the heating equipment depends on how responsibly you approach this issue. Stable operation of the burner, compliance with environmental standards, longer service life of boilers and the ability to fully automate the operation of a thermal power plant indicate significant advantages of using modulating burners in boiler houses. And if the benefit from their operation is obvious, not taking advantage of it is simply unreasonable.
Burners Weishaupt / Germany Elco/ Germany , Cib Unigas / Italy, Baltur / Italy have proven themselves to be reliable and quality equipment. By choosing these burners, you get confidence and profit! In turn, we are ready to provide you with reasonable prices and as soon as possible supply of equipment.
Manufacturers of domestic heating boilers, constantly improving their products and providing them with new functions, at the same time make it more difficult to select the right boiler and set it up. This applies to the greatest extent to boiler automation - and now wall-mounted boilers, previously controlled with a single potentiometer, are now often supplied with built-in weather-compensating automation. However, more a complex system management is always a higher price. A reasonable question arises: “Is this necessary?” To help consumers answer this question, we will try to understand the main functions of boiler automation.
The purpose of control systems for domestic boilers is to ensure safety, correct operation equipment and comfort for those living in a house or apartment. Comfort in our case is a comfortable temperature and the absence of the need to take any action to ensure it (for example, go to the boiler room, turn the regulator, etc.).
The situation with safety is most simple and clear: whether the control system is built into the boiler, or it is supplied separately, it always has a safety temperature limiter. This device is a thermal relay, the opening of the contacts of which leads to the cessation of fuel supply to the boiler when the safe temperature of the boiler water is exceeded. Triggering of the safety temperature limiter is a serious emergency situation, and its elimination, i.e. Replacing or reinstalling the safety device and starting the boiler require the intervention of a maintenance specialist.
It goes without saying that safety has the highest priority among other tasks, so the upper limit for boiler water temperature control is set so that the temperature never exceeds the limit level due to run-on. What kind of run-out? temperature goes speech?
Imagine the situation of a sudden power outage: the burner turned off, circulation pump the boiler circuit has stopped. The boiler turns into an isolated system. During installation in this thermal equilibrium system, the temperature of the metal decreases and the temperature of the water increases by several degrees. If before this increase it was close to the maximum permissible, then a boiler failure during a power outage is guaranteed. The magnitude of the possible temperature rise depends on the design and material of the boiler and is taken into account by the automation manufacturer when setting the upper limit for regulating the water temperature in the boiler.
Let's move on to the main purpose of boiler automation: ensuring a comfortable temperature in heated rooms. As is known, a particular temperature in a room is established when a balance is reached between heat losses and heat transfer from heating devices. At the same time, in order to maintain a given temperature value, any change in heat loss caused by a change in weather must be compensated by an appropriate correction of the temperature of the coolant or its volumetric flow through the heating devices. This problem is most easily solved with the help of thermostatic valves installed on radiators or convectors, while the temperature of the coolant remains constant. In this case, the function of boiler automation is reduced to maintaining the set supply temperature.
It must be said that most household boilers have a built-in control unit and do not require anything more: the supply temperature is set manually, although it is maintained automatically. The control algorithm differs depending on which burner the boiler is equipped with: modulating, one- or two-stage. In boilers with a single-stage burner, the temperature controller acts as a threshold switch that turns the burner on and off when the supply temperature reaches the threshold values. Between switching thresholds and
switching off, a certain difference is specified - switching hysteresis (Fig. 1). As a rule, the on and off thresholds are located symmetrically with respect to the set supply temperature θ mouth so that the average temperature value over a long period coincides with the set one.
If the volume of coolant in the heating system is small and heat consumption is significant less power burner, the temperature will rise too quickly after turning on the burner. Accordingly, there is a danger of turning on the burner too frequently, which can also affect its service life. This problem is being overcome different ways. For example, using a time-varying hysteresis value (Ariston): during the 1st minute after switching on it is 8, during the 2nd minute - 6, and starting from the 3rd minute - 4 K.
The algorithm for changing the hysteresis value depending on the situation is embedded in the Kromschröder automation: at the service level of the control system settings, you can set an increased hysteresis (up to 20 K) and its duration (up to 30 minutes). At low heat loads and, accordingly, short boiler heating periods, an increased hysteresis value applies. If the switch-off threshold has not been reached within the specified hysteresis time, the hysteresis value is automatically linearly reduced to the standard 5 K. 
A fundamentally different approach is used in Buderus boiler automation, which uses an algorithm called “dynamic switching” by the developers. When the supply temperature, increasing or decreasing, is compared with the set temperature θset, the system begins to calculate the integral of the function of changing the mismatch over time (shaded area in Fig. 2). The burner is turned on or off when the integral reaches the set value. Obviously, with rapid heating of the boiler, the switching temperature is higher than with slow heating. Thus, the switching threshold is automatically adjusted to the characteristics of the heating system and the amount of heat consumption.
The control algorithm for a boiler with a two-stage burner is not fundamentally different from what is discussed above - only the switching thresholds are, accordingly, twice as large (Fig. 3). 
Finally, the modulating burner allows for constant proportional control of the supply temperature, where the burner output is linearly dependent on the temperature mismatch. However, such regulation is not always possible, since for many modulating burners the power smoothly changes not from zero, but from 30-40% of the maximum value. If the heat consumption in the heating circuit is below this limit, then we are again faced with threshold regulation.
So far we have meant that the flow temperature is set manually by a potentiometer on the boiler control panel and is automatically maintained by its control system. However, the purpose of the heating system is to maintain a comfortable temperature in the room, and it would be logical for this particular temperature to be a controlled variable. A device that maintains a given room temperature - room thermostat- most often tied to the room itself and is not included in the main boiler delivery package. However, since regulation occurs through the control of the boiler operation, we will consider the room thermostat also an element of boiler automation.
Control of the boiler operation in order to maintain the set temperature in the room can be carried out by one of two types of control: two-position (on-off) or continuous. In the first case, the control algorithm is the same as for a boiler with a single-stage burner. However, compared to the temperature of the boiler water, the temperature in the room changes much more slowly when the boiler is turned on and off, which can lead to large deviations beyond the threshold values. Therefore, on-off control is usually not recommended for heating systems with high-power (more than 25-30 kW) boilers. To avoid such runs in Kromschröder automation, for example, at the service level a delay time interval for turning on the 2nd stage can be set (Fig. 3), and thus the 2nd stage is turned on not immediately upon reaching the threshold θon.2, but after after a specified time. This gives additional opportunity settings of the temperature controller for the characteristics of a specific heating system. 
With continuous regulation, the control action is the supply temperature, which changes depending on the deviation of the room temperature from the set value (Fig. 4). The room temperature set point is a temperature that is comfortable for the user, and it is not always the same - say, a comfortable temperature for sleeping under a blanket is several degrees lower than for the morning or evening hours, and during the day the room may be empty, and maintain it high temperature also doesn't make sense. The function of setting and executing a daily temperature schedule in the room naturally suggests itself. Daily temperature programming is often possible for different weekdays or weekends, as well as for special occasions such as a party or vacation.
The actual temperature value is measured by a sensor located in one of the rooms of the house, which is a reference and determines the heating mode in all other rooms of the house. However, the larger the number of other rooms, the less feasible the task of comfortable heating becomes by linking them into a single heating circuit controlled by the temperature in the reference room. To control a boiler that heats water for several heating circuits at once with different characteristics, a certain input parameter common to these circuits is required. It could be calculated based on temperature readings in reference rooms of all circuits. However, a simpler and more effective solution has become widespread: using the air temperature outside the building as such a parameter. 
And indeed: the supply temperature of any heating circuit, necessary to compensate for heat loss in premises, is related to the outside air temperature by well-known relationships, which in graphical representation are usually called heating graphs or heating curves (Fig. 5). All that remains is to include these relationships for each specific circuit in the operating algorithm of the boiler room control system. In the automation of most manufacturers, for this you need to select one of the heating curves offered to choose from, but there are other approaches: for example, the Buderus control system adjuster only needs to specify two points from which the automation calculates the entire curve.
Can a system that controls the boiler and heating circuits based on external temperature respond to unexpected changes in the heat balance in heated rooms, for example, due to an open window or a lit fireplace? In most cases, this possibility is provided in the form of automatic adjustment (most often parallel transfer) of the heating curve of the corresponding circuit based on the readings of the room temperature sensor. Moreover, meeting the needs of meticulous users who want to take a more active part in controlling the climate in the house, many manufacturers offer, in addition to weather-dependent automation, a room thermostat. Let us only note that in this case there is always a risk, while increasing comfort in the reference room, reducing it in other rooms connected to the same heating circuit. In addition, thermostats cannot be used in the reference room. heating devices, since they are independent control systems with the same input and output parameters as boiler automation.
Why all this complexity? How is weather-dependent control better than the elementary scheme we considered at the very beginning - a “permanent” boiler plus thermostats on all heating devices? 
Proponents of weather-compensated automation usually refer to the fact that the main part heating season the heat demand is much less than the calculated one, so constantly heating the coolant to the maximum temperature is a waste of money. But it’s not the temperature that costs money, but the heat produced, and if in two cases the same amount of heat is consumed, then perhaps the same amount of heat is produced? Unfortunately, no, because in addition to heat consumption, there are always heat losses, which are greater the higher the coolant temperature (Fig. 6). In addition, the boiler efficiency decreases with increasing average boiler water temperature. It is these percentages that make up the economic argument in favor of weather-sensitive automation. However, with our domestic prices For energy resources, this argument is easily defeated by the argument of the significantly higher price of the automation itself.
Let's also consider some functions of boiler automation, the purpose of which is not to create comfort, but to ensure the longest possible trouble-free operation of the equipment. In addition to the methods already described for preventing too frequent burner starts, this group of functions includes maintaining minimum temperature boiler water. The simplest, but nevertheless effective method The implementation of this function is the so-called pump logic, according to which, when the burner is on, the circulation pump of the boiler circuit stops whenever the water temperature in the boiler is below the permissible threshold and does not start until this threshold is exceeded.
But boiler automation can take care of not only the boiler. Thus, some control systems are equipped with a function to prevent blocking of pumps and three-way valves: once a day (example - Vaillant boilers) or a week (Buderus) all pumps in the system are turned on for a short time, and all three-way valves are also fully opened for a short time, after which returns to the state that preceded this procedure.
When reading documentation from manufacturers, one gets the impression that developers of boiler control systems act on the principle: “more functions - good and different!” True, it often turns out that the same functions are hidden under different names, the differences are only in the details.
S. Zotov, Ph.D.
Magazine "Aqua-Term" No. 2 (54), 2010
To choose the optimal gas boiler, you need to understand its features.
The most widely used in everyday life hot water boilers low power.
These units are economical and easy to use, and also have many configurations and models, each of which has its own advantages.
One of the main elements gas boiler is its burner. This is special equipment that prepares fuel for combustion and supplies it to the combustion chamber, where a stream of gas-air mixture ignites and releases heat. Choosing the right burner will ensure you get maximum efficiency combustion of fuel, will increase the overall efficiency (efficiency factor) of the boiler and reduce financial costs for fuel.
Classification of gas burners
There are different types of gas burners. To do right choice burners, you need to take into account the type of gas burned, its calorie content, pressure, purpose and design of the boiler.
By excess gas pressure
- High pressure – more than 30 kPa. (kilo Pascal);
- Medium pressure – from 5 to 30 kPa;
- Low pressure – up to 5 kPa.
By type of fuel burned
Domestic and industrial hot water gas boilers usually operate on two types of fuel:
- liquefied propane-butane mixture;
- natural gas (methane) in gaseous state.
The physical characteristics of these gases differ from each other, therefore the burner devices for burning them have their own differences. But the type of fuel burned does not limit the choice of unit. Any natural gas boiler can be converted to burn propane and vice versa.
On a note.Universal burners have been developed that can burn these two types gas fuel without any adjustments.
According to the method of preparing the gas-air mixture
To ensure complete and efficient combustion of fuel, it must first be mixed with air, which contains the oxygen necessary for combustion. There are several ways to prepare a gas-air mixture.
Atmospheric burners have simple design in the form of a pipe with holes. Gas is supplied into the pipe and exits from the holes into the combustion chamber, where it is mixed with air. Combustion chambers are used to ensure a constant flow of air open type.
Advantages of atmospheric burners:
- Simplicity of design.
- It can be easily converted to burn another type of fuel.
- Long service life.
- High efficiency indicators.
- Energy independence.
Disadvantages of atmospheric burners:
- Burning oxygen in the room and the possibility of combustion products leaking into the room.
- It is necessary to have an exhaust chimney, which is not always possible.
- Limited boiler power associated with the increased danger of an open combustion chamber.
Blast (fan) burners have more complex design including a fan. It produces forced air injection, in required quantities, and mixing it with gas. Mixing can occur completely pre-mixing, partially pre-mixing and during combustion.
The use of forced-air burners involves the use of boilers with closed camera combustion, in this case it is necessary to have an additional fan to suck out combustion products. Gas boilers with forced draft do not require a bulky flue. Gases can be removed using a small diameter chimney.
Advantages of forced-air burners:
- Opportunity efficient work at reduced pressure in the gas pipeline.
- Operational safety due to a closed combustion chamber.
- When operating a boiler with a forced-air burner, there is no need for a chimney.
- Possibility of replacement with a different type of burner.
- More efficient system protection.
Disadvantages of forced-air burners:
- High price.
- High noise level.
- Energy dependence.
- Additional gas consumption.
Diffuse-kinetic gas burners. Air is partially added to the combustion chamber, the rest is supplied directly to the flame. Such burners are rarely used in gas heating boilers.
According to the method of regulating combustion intensity.
To ensure continuous maintenance temperature regime used indoors automatic systems. Automation for gas heating boilers is prerequisite, because a person cannot always control the operation of the boiler. The automation performs the following functions: regulating the air temperature in the room and protecting the boiler from accidents. There are several types of burners depending on the type of temperature control.
- Single-stage - after heating the coolant to the desired temperature, according to a signal from the rheostat, the gas valve automatically closes and the burner goes out completely. As soon as the coolant temperature reaches the lower temperature limit gas valve automatically opens and the burner ignites at full power.
- Two-stage burners have 2 operating modes: 100% and 40% of total power. After reaching a certain temperature value of the coolant, the gas valve closes and the burner operates at 40% of full power. The process of transition from one operating mode to another is carried out using an automatic system.
- Continuously adjustable two-stage burners also have 2 operating modes, but the transition from one mode to another occurs more smoothly, which ensures effective temperature control.
- Modulating gas burners can operate in modes with a wide power range - from 10 to 100%. The regulation process is fully automated and ensures the most efficient and constant maintenance of temperature conditions.
The undoubted leader in operational efficiency are modulating gas burners, as they provide:
- Constantly maintaining the set temperature with minimal deviations.
- Saving burned fuel.
- Reducing the temperature load on the boiler heat exchanger, which significantly extends its service life.
Modulating burners can be either atmospheric or fan-driven gas burners, and they can also operate on different types of fuel.
After familiarizing yourself with various types gas burners, you can confidently make a decision about choosing exactly the burner that is suitable for your purposes.
Manufacturers of modern boilers, constantly improving their products, endow them with new functions and at the same time complicate the selection of the right boiler and its adjustment. This is no wonder, because the heating system of a modern country house consists not only of a boiler, pipes, radiators under the windows, but it also includes many heating circuits, the management of which should be entrusted to automatic controllers.
Otherwise, homeowners will have to constantly adjust individual elements manually to ensure a sufficient level of comfort. However, a more complex control system always means a higher price. “Do I need this?” — the buyer asks a rhetorical question.
In this short article we will try to convey to readers the physics of processes in a working heating system, which is inherent in all heating systems, including complex ones. Having an idea of what you have or are planning to buy is very important when choosing a heating system, its operation or modification. To the structure modern systems heating system already has functions that require its modification and improvement.
So, boiler automation is assigned two important functions: a security system and thermal comfort. Of course, ensuring safety has the highest priority among other tasks. For example, the upper limit for boiler water regulation is set in such a way that due to temperature overrun it never exceeds the limit level. The magnitude of the possible temperature rise depends on the design and material of the boiler and is taken into account by the automation manufacturer when setting the upper limit for temperature control in the boiler.
In our article we focus on the operation of automation to ensure a comfortable temperature in heated rooms.
The feeling of thermal comfort is largely subjective. In this regard, experts in the field climate systems operate with the concept of comfort index according to Fagner. It provides seven positions corresponding to subjective sensations
- -3 “cold”
- -3 “cool”
- -1 “slight coolness”
- 0 "neutral"
- 1 "light heat"
- 2 "warmth"
- 3 "hot"
A particular temperature in the room is established when a balance is reached between heat losses and heat transfer from devices. At the same time, in order to maintain the set temperature value, any change in heat loss caused by weather changes must be compensated by appropriate correction of the coolant temperature or its volumetric flow through the heating devices.
Let us first consider the second case, namely the regulation of room temperature by changing the volume flow through heating devices.
This problem is easily solved using thermostatic valves installed on radiators or convectors. In this case, the task of the boiler automation is to maintain the coolant temperature at a given level (simply turn the potentiometer knob on the boiler remote control, setting desired temperature). In most boilers, this is what happens and does not imply anything more. The boiler operation algorithm differs depending on the burner: modulating, one or two-stage.
When working with a single-stage burnerThe temperature controller works as a threshold switch that turns the burner on and off when the supply temperature reaches threshold values. There is a certain difference between the on and off thresholds - “on hysteresis”. As a rule, the on and off thresholds are located symmetrically with respect to the set supply temperature, so that the average temperature value over a long period coincides with the set one.
Problem occurs when the volume of coolant is small and the heat consumption is significantly less than the burner power, the burner temperature will rise too quickly. Occurs danger of turning on the burner too frequently, which may affect its resource. The problem is overcome in various ways. For example, using a time-varying hysteresis value.
At low heat loads and, accordingly, short boiler heating periods, an increased hysteresis value applies. If the switch-off threshold has not been reached within the specified hysteresis time, the hysteresis value is automatically linearly reduced to the standard 5 g. Celsius. Buderus uses a different algorithm called “dynamic switching” - when the supply temperature, increasing or decreasing, is compared with the set temperature and the system begins to calculate the integral of the function of changing the mismatch over time.
The burner is switched on and off when the integral reaches the set value, such that when the boiler heats up quickly, the switching temperature is higher than when the boiler heats up slowly. Thus, the switching threshold is automatically adjusted to the characteristics of the heating system and the amount of heat consumption
For two-stage burner the process is not fundamentally different from what was discussed above - only there are twice as many switching thresholds.
Modulating burner makes it possible to constantly proportionally control the supply temperature, when the burner power value linearly depends on the temperature mismatch value. However, such regulation is not always possible, since for many modulating burners the power smoothly changes not from zero, but from 30-40% of the maximum value. If the heat consumption in the heating circuit is below this limit, then we are again faced with threshold regulation. Until now, we have considered processes when the set boiler temperature was set manually using a potentiometer on the boiler remote control, and the task of the boiler automation was to maintain this temperature.
Maintaining a comfortable room temperature by regulating the boiler water temperature. This happens by introducing a room thermostat into the automation system.
Please note that a room thermostat is usually not included in the standard equipment of the boiler. Control of the boiler operation in order to maintain the set temperature in the room can be carried out by one of two types of regulation: two-position (on/off) or continuous. In the first case, the control algorithm is the same as for a boiler with a single-stage burner. However, compared to the boiler water temperature, the room temperature changes much more slowly and this can lead to large overruns beyond the threshold values. Therefore, on-off control is usually not recommended for heating systems with boilers larger than 25-30 kW.
With continuous regulation The control action is the supply temperature, which changes depending on the temperature deviation in the room. The temperature sensor must be located in a specific room (let's call it a reference room) and the temperature in other rooms is set relative to the temperature of this reference room. Comfortable temperature in different rooms different from each other. In the bedroom, for example, it is lower. During the day the premises are usually empty and maintained comfortable temperature- pointless, a waste of money.
The function of setting and executing a daily temperature schedule in the premises naturally suggests itself. Daily temperature programming is often possible for different days weeks (weekdays, holidays, parties, vacations). Big problem With this control method, the temperature in the rooms is regulated relative to the reference one, by linking it into a single circuit.
In addition, by increasing comfort in the reference room, we risk reducing it in other rooms connected to the same control loop. In addition, in the reference room it is impossible to use thermostats on heating devices, since they are independent control systems with the same input parameters as boiler automation.
To control a boiler that heats water for several heating circuits with different characteristics at once, a certain input parameter common to these circuits is required. Simple and effective solution was found.
Using air temperature outside the building as an input parameter
Indeed, the supply temperature of any heating circuit necessary to compensate for heat loss in rooms is related to the outside air temperature by well-known relationships, which in graphical representation are usually called heating graphs or heating curves. All that remains is to include these relationships for each specific circuit in the operating algorithm of the boiler room control system. In the automation of most manufacturers, for this you need to select one of the proposed curves. There are other approaches to this problem, for example, it is enough for a Buderus boiler adjuster to set two points from which the automation itself will construct the entire curve. Note that it is extremely important to place the temperature sensor on the north side of the house away from heat sources such as windows and chimneys. In this case, the weather-compensated automation works as correctly as possible.
What happens if you open the window? System that controls the boiler and heating circuits according to external temperature, can respond to unexpected changes in the heat balance in heated rooms. In most cases, this possibility is provided in the form of automatic adjustment (most often parallel transfer) of the heating curve of the corresponding circuit based on the readings room sensor temperature.
Moreover, many manufacturers offer, in addition to weather-compensated automation, a room thermostat. When using external and room sensors The thermal regime can be adjusted taking into account additional sources heat in the room. Simply put, if the stove is turned on in the kitchen, and due to this it has become warmer there, the controller will “take into account” this fact and adjust the indicators external sensors or is the room located on sunny side and requires heating only when the sun “goes away”.
As automation becomes more expensive, its capabilities are enhanced by the ability to control more complex burners (with step, step-progressive and modulation control), cooking unit hot water, one or more (the number of radiator circuits is growing), low-temperature (warm floor) circuits, implement various other programs (connection solar water heaters) etc.
Let's summarize: why all these difficulties with weather-dependent control? How is it better than the simple “permanent boiler” scheme plus thermostats on all batteries?
Proponents of weather-sensitive management they say that during the main part of the heating season, the heat demand is much less than the calculated one, so constantly heating the coolant to the maximum temperature is a waste of money. It works especially effectively during periods of frost and thaw, thereby achieving the most comfortable room temperature and significant savings in resources, since the inertia of the system is reduced and the boiler does not have to do extra work by burning fuel. In addition, in the case of working with a constant temperature of the coolant, and it is almost always high, heat loss increases, which is greater, the more higher temperature coolant. In general, boiler efficiency decreases with increasing average boiler water temperature.
Most Western manufacturers ( « Buderus» , "Viessmann") bet onproduction of low-temperature boilers.
Opponents of weather-independent control argue that the price of such automation is too high. And the price of fuel so far fully compensates for the costs.
Let's turn to the specialists. on the forum, the site clearly says that weather-proof automation saves money, and this is not counting the comfort that it brings to the house and ensures longer trouble-free operation.
The Time company offers a programmable controller as weather-compensating automation calorMATIC 430 West. In fact it works like remote from the boiler. The homeowner does not have to run to the boiler room to turn it warmer or cooler if he installs the display panel in a convenient location.
