Hello, friends. What optimal mode gas boiler operation? There are a number of contributing factors here. These are the conditions of its work, and the potential, and the design, etc.
The main motive for finding a better regime is economic benefit. At the same time, the equipment should give maximum efficiency, and fuel consumption is minimal.
Factors affecting the operation of the boiler
They are:
- Design. A technique can have 1 or 2 circuits. It can be wall or floor mounted.
- Normative and actual efficiency.
- Competent arrangement of heating. The power of technology is comparable to the area that needs to be heated.
- Technical conditions of the boiler.
- Gas quality.
All these points need to be optimized so that the device gives the best efficiency,
Design question.
The device can have 1 or 2 circuits. The first option is complemented by an indirect heating boiler. The second already has everything you need. And the key mode in it is to provide hot water. When water is supplied, heating is completed.
Wall-mounted models have less power than those placed on the floor. And they can heat a maximum of 300 sq.m. If your living area is larger, you will need a floor standing unit.
P.2 efficiency factors.
The document for each boiler reflects the standard parameter: 92-95%. For condensation modifications - approximately 108%. But the actual parameter is usually lower by 9-10%. It decreases even more due to heat losses. Their list:
- Physical malaise. The reason is excess air in the apparatus when the gas is burned, and the temperature of the exhaust gases. The larger they are, the more modest the efficiency of the boiler.
- Chemical burn. What is important here is the amount of CO2 oxide that occurs when carbon is burned. Heat is lost through the walls of the apparatus.
Methods for increasing the actual efficiency of the boiler:
- Elimination of soot from the pipeline.
- Elimination of scale from the water circuit.
- Limit chimney draft.
- Adjust the position of the blower door so that the heat carrier acquires the maximum temperature.
- Elimination of soot in the combustion chamber.
- Installation of a coaxial chimney.
P.3 Questions on heating. As already noted, the power of the device necessarily correlates with the heating area. A smart calculation is needed. The specifics of the structure and potential heat losses are taken into account. It is better to entrust the calculation to a professional.
If the house is built according to building codes, the formula is 100 W per 1 sq.m. It turns out this table:
| Area (sq.m.) | Power. | ||
| Minimum | Maximum | Minimum | Maximum |
| 60 | 200 | 25 | |
| 200 | 300 | 25 | 35 |
| 300 | 600 | 35 | 60 |
| 600 | 1200 | 60 | 100 |
Acquire better boilers foreign production. Also in the advanced versions there are many useful options to help you achieve the optimal mode. One way or another, the optimal power of the device is in the range of 70-75% of the highest value.
technical conditions. To prolong the life of the device, remove soot and scale from internal parts in a timely manner.
The optimal mode of operation of a gas boiler to save gas is achieved by eliminating clocking. That is, you need to set the gas supply to the smallest value. The attached instructions will help you with this.
There is an aspect that cannot be influenced - this is the quality of the gas.
Methods for setting the optimal mode
Many devices are programmed for the temperature of the thermal carrier. When it reaches the required values, the unit briefly turns off. The user can set the temperature himself. The parameters also change depending on the weather. For example, the optimal mode of operation of a gas boiler in winter is obtained at values of 70-80 C. In spring and autumn - at 55 - 70 C.
IN modern models there are temperature sensors, thermostats and auto-tuning modes.
Thanks to the thermostat, you can set the desired climate in the room. And the heat carrier will warm up and cool down with a specific intensity. At the same time, the device reacts to temperature fluctuations in the house and outside. This is the optimal mode of operation of the outdoor gas boiler. Although with the help of such devices it is possible to optimize and hinged model. At night, the parameters can be reduced by 1-2 degrees.
Thanks to these devices, gas is spent less by 20%.
If you want solid efficiency and savings from the boiler, purchase the desired model. The following are some examples.
Model examples
- Baksi.
The optimal mode of operation of this wall-mounted gas boiler is achieved as follows: small apartments indicators are set to F08 and F10. The modulation spectrum starts at 40% of the highest power. And the minimum possible operating mode is 9 kW.
Many models of this company are very economical and can work at low gas pressure. Pressure limits: 9 - 17 mbar. Suitable voltage range: 165 - 240 V.
- Vaillant.
Many devices of this brand work optimally under such conditions: power - 15 kW. Submission is placed at 50-60. The device works for 35 minutes, rests for 20 minutes.
- Ferroli.
Best conditions: 13 kW for heating, 24 kW for water heating.
- Mercury.
The water pressure in the network is a maximum of 0.1 MPa. The highest temperature indicator at the outlet section is 90 C, the nominal value of flue gases is at least 110 C. The vacuum downstream of the apparatus is a maximum of 40 Pa.
- Navien.
Basically, these are two-circuit units. Automation works here. The mode is self-configuring. Sets the room heating setting. There is a pump that can reduce the parameters by 4-5 degrees.
- Ariston.
The automatic mode setting also works. Often people choose models with the "Comfort-Plus" mode.
- Buderus.
Values are usually set on the feed: 40 - 82 C. The current parameter is usually reflected on the monitor. The most comfortable summer mode- at 75 C.
Conclusion
Thanks to the gas boiler, you can conveniently adjust the climate in the house. Especially if you use innovative technology with automatic modes and many useful options.
2.KIT of the boiler at different temperatures of the incoming
The lower the temperature enters the boiler, the greater the temperature difference on different sides of the boiler heat exchanger partition, and the more efficiently the heat passes from the exhaust gases (combustion products) through the heat exchanger wall. I will give an example with two identical kettles placed on the same burners. gas stove. One burner is set to high flame and the other to medium. The kettle with the highest flame will boil faster. And why? Because the temperature difference between the combustion products under these kettles and the water temperature for these kettles will be different. Accordingly, the rate of heat transfer at a larger temperature difference will be greater.
With regard to the heating boiler, we cannot increase the combustion temperature, as this will lead to the fact that most of our heat (gas combustion products) will fly out through the exhaust pipe into the atmosphere. But we can design our heating system (hereinafter referred to as CO) in such a way as to lower the temperature entering into, and therefore, lower the average temperature circulating through. The average temperature at the return (inlet) to and supply (outlet) from the boiler will be called the temperature of "boiler water".
As a rule, the 75/60 mode is considered the most economical thermal mode of operation of a non-condensing boiler. Those. with a temperature at the supply (outlet from the boiler) +75 degrees, and at the return (inlet to the boiler) +60 degrees Celsius. A reference to this thermal regime is in the boiler passport, when indicating its efficiency (usually indicate the mode 80/60). Those. in a different thermal regime, the efficiency of the boiler will be lower than stated in the passport.
That's why modern system heating must operate in the design (for example, 75/60) thermal mode for the entire heating period, regardless of the outside temperature, except when using an outside temperature sensor (see below). The regulation of heat transfer from heating devices (radiators) during the heating period should be carried out not by changing the temperature, but by changing the amount of flow through the heating devices (the use of thermostatic valves and thermoelements, i.e. "thermal heads").
In order to avoid the formation of acid condensate on the boiler heat exchanger, for a non-condensing boiler, the temperature in its return (inlet) should not be lower than +58 degrees Celsius (usually taken with a margin of +60 degrees).
I will make a reservation that the ratio of air and gas entering the combustion chamber is also of great importance for the formation of acid condensate. The more excess air entering the combustion chamber, the less acidic condensate. But you should not rejoice at this, since excess air leads to a large overspending of gas fuel, which ultimately "beats us in the pocket."
For example, I will give a photo showing how acid condensate destroys the boiler heat exchanger. The photo shows the heat exchanger of the wall-mounted boiler Vailant, which worked for only one season in an incorrectly designed heating system. Quite strong corrosion is visible on the return (inlet) side of the boiler.
For condensation, acid condensate is not terrible. Since the heat exchanger of the condensing boiler is made of special quality alloyed of stainless steel, which is "not afraid" of acid condensate. Also, the design of the condensing boiler is designed so that acidic condensate flows through a tube into a special container for collecting condensate, but does not fall on any electronic components and components of the boiler, where it could damage these components.
Some condensing boilers are able to change the temperature on their return (inlet) by themselves due to the smooth change of power by the processor of the boiler circulation pump. Thereby increasing the efficiency of gas combustion.
For additional gas savings, use the connection of the outdoor temperature sensor to the boiler. Most wall-mounted ones have the ability to automatically change the temperature depending on the outside temperature. This is done so that at outdoor temperatures that are warmer than the temperature of the cold five-day period (the most severe frosts), the temperature of the boiler water is automatically lowered. As mentioned above, this reduces gas consumption. But when using a non-condensing boiler, it is important not to forget that when the temperature of the boiler water changes, the temperature at the return (inlet) of the boiler should not fall below +58 degrees, otherwise acid condensate will form on the boiler heat exchanger and destroy. To do this, when commissioning the boiler, in the boiler programming mode, such a curve of temperature dependence on the outside temperature is selected, at which the temperature in the boiler return would not lead to the formation of acid condensate.
I want to warn you right away that when using a non-condensing boiler and plastic pipes in the heating system, installing a street temperature sensor is almost pointless. Since we can design for the long-term service of plastic pipes, the temperature at the boiler supply is not higher than +70 degrees (+74 during the cold five-day period), and in order to avoid the formation of acid condensate, design the temperature at the boiler return is not lower than +60 degrees. These narrow "frames" make the use of weather-dependent automation useless. Since such frames require temperatures in the range of +70/+60. Already when using copper or steel pipes in the heating system, it already makes sense to use weather-compensated automation in heating systems, even when using a non-condensing boiler. Since it is possible to design the thermal mode of the boiler 85/65, which mode can be changed under the control of weather-dependent automation, for example, up to 74/58 and save on gas consumption.
I will give an example of an algorithm for changing the temperature at the boiler supply depending on the outside temperature using the Baxi Luna 3 Komfort boiler as an example (below). Also, some boilers, for example, Vaillant, can maintain the set temperature not on their supply, but on their return. And if you set the return temperature maintenance mode to +60, then you can not be afraid of the appearance of acid condensate. If at the same time the temperature at the boiler supply changes up to +85 degrees inclusive, but if you use copper or steel pipes, then such a temperature in the pipes does not reduce their service life.
From the graph, we see that, for example, when choosing a curve with a coefficient of 1.5, it will automatically change the temperature at its supply from +80 at a street temperature of -20 degrees and below, to a supply temperature of +30 at a street temperature of +10 (in the middle section flow temperature curve +.
But how much the supply temperature of +80 will reduce the service life of plastic pipes (Reference: according to manufacturers, the warranty service life plastic pipe at a temperature of +80, it is only 7 months, so do not hope for 50 years), or a return temperature below +58 will reduce the life of the boiler, unfortunately, there is no exact data announced by the manufacturers.
And it turns out that when using weather-dependent automation with non-condensing gas, you can save something, but it is impossible to predict how much the service life of the pipes and the boiler will decrease. Those. in the above case, the use of weather-compensated automation will be at your own peril and risk.
Thus, it makes the most sense to use weather-compensated automation when using a condensing boiler and copper (or steel) pipes in the heating system. Since weather-dependent automation will be able to automatically (and without harm to the boiler) change the thermal regime of the boiler from, for example, 75/60 for a cold five-day period (for example, -30 degrees outside) to the 50/30 mode (for example, +10 degrees outside) street). Those. you can painlessly choose the dependence curve, for example, with a coefficient of 1.5 without fear of a high boiler supply temperature in frost, at the same time without fear of the appearance of acid condensate during thaws (for condensation, the formula is valid that the more acid condensate is formed in them, the more they save gas). For interest, I will lay out a graph of the dependence of the KIT of a condensing boiler, depending on the temperature in the return of the boiler.
3.KIT of the boiler depending on the ratio of the mass of gas to the mass of air for combustion.
The more it burns gas fuel in the combustion chamber of the boiler, the more heat we can get from burning a kilogram of gas. The completeness of gas combustion depends on the ratio of the mass of gas to the mass of combustion air entering the combustion chamber. This can be compared to the tuning of a carburetor in a car's internal combustion engine. The better the carburetor is tuned, the less for the same engine power.
To adjust the ratio of gas mass to air mass in modern boilers, special device, dosing the amount of gas supply to the combustion chamber of the boiler. It is called a gas fitting or an electronic power modulator. The main purpose of this device is automatic modulation of the boiler power. Also, the adjustment of the optimal ratio of gas to air is carried out on it, but already manually, once during commissioning of the boiler.
To do this, when commissioning the boiler, you must manually adjust the gas pressure using a differential pressure gauge on special control fittings of the gas modulator. Two pressure levels are adjustable. For maximum power mode, and for minimum power mode. The methodology and instructions for setting up are usually set out in the boiler's passport. You can not buy a differential pressure gauge, but make it from a school ruler and a transparent tube from a hydraulic level or a blood transfusion system. The gas pressure in the gas line is very low (15-25 mbar), less than when a person exhales, therefore, in the absence of an open fire nearby, such a setting is safe. Unfortunately, not all service workers, when commissioning the boiler, perform the procedure for adjusting the gas pressure on the modulator (out of laziness). But if you need to get the most economical operation of your heating system in terms of gas consumption, then you must definitely perform such a procedure.
Also, when commissioning the boiler, it is necessary, according to the method and table (provided in the boiler passport), to adjust the diaphragm cross section in the boiler air pipes depending on the boiler power and the configuration (and length) of the exhaust pipes and combustion air intake. The correctness of the ratio of the volume of air supplied to the combustion chamber to the volume of supplied gas also depends on the correct choice of this section of the diaphragm. Correct this ratio ensures the most complete combustion of gas in the combustion chamber of the boiler. And, therefore, it reduces to necessary minimum gas consumption. I will give (for an example of a technique correct installation aperture) scan from the passport of the boiler Baxi Nuvola 3 Comfort -
4. KIT of the boiler, depending on the temperature of the air entering it for combustion.
Also, the economy of gas consumption depends on the temperature of the air entering the combustion chamber of the boiler. The efficiency of the boiler given in the passport is valid for the temperature of the air entering the combustion chamber of the boiler +20 degrees Celsius. This is due to the fact that when colder air enters the combustion chamber, part of the heat is spent on heating this air.
Boilers are "atmospheric", which take air for combustion from the surrounding space (from the room in which they are installed) and "turbo boilers" with a closed combustion chamber, into which air is forcibly supplied by a turbocharger located in. Ceteris paribus, a "turbo boiler" will have greater gas consumption efficiency than an "atmospheric" one.
If everything is clear with the “atmospheric” one, then with the “turbo boiler” questions arise from where it is better to take air into the combustion chamber. The “Turboboiler” is designed so that the air flow into its combustion chamber can be arranged from the room in which it is installed, or directly from the street (using a coaxial chimney, i.e. a “pipe in pipe” chimney). Unfortunately, both of these methods have their pros and cons. When air enters from interior spaces at home, the temperature of the air for combustion is higher than when taken from the street, but all the dust generated in the house is pumped through the combustion chamber of the boiler, clogging it. The combustion chamber of the boiler is especially clogged with dust and dirt during finishing works in the house.
Don't forget that for safe work"atmospheric" or "turbo boiler" with air intake from the premises of the house, it is necessary to organize the correct operation of the supply part of the ventilation. For example, supply valves on the windows of the house must be installed and opened.
Also, when removing the products of combustion of the boiler up through the roof, it is worth considering the cost of manufacturing an insulated chimney with a steam trap.
Therefore, the most popular (including for financial reasons) are the coaxial chimney systems “through the wall to the street”. Where exhaust gases are emitted through the inner pipe, and combustion air is pumped in from the street through the outer pipe. In this case, the exhaust gases heat up the air drawn in for combustion, since the coaxial pipe acts as a heat exchanger.
5.KIT of the boiler depending on the time of continuous operation of the boiler (lack of “clocking” of the boiler).
Modern boilers themselves adjust their output. thermal power, under the thermal power consumed by the heating system. But the limits of auto-tuning power are limited. Most non-condensing units can modulate their power from about 45% to 100% of rated power. Condensing modulate power in a ratio of 1 to 7 and even 1 to 9. Ie. a non-condensing boiler with a rated power of 24 kW will be able to produce at least, for example, 10.5 kW in continuous operation. And condensing, for example, 3.5 kW.
If at the same time the temperature outside is much warmer than in a cold five-day period, then there may be a situation where the heat loss of the house is less than the minimum possible generated power. For example, the heat loss of a house is 5 kW, and the minimum modulated power is 10 kW. This will lead to periodic shutdown of the boiler when the set temperature at its supply (output) is exceeded. It may happen that the boiler will turn on and off every 5 minutes. Frequent switching on / off of the boiler is called “clocking” of the boiler. Clocking, in addition to reducing the life of the boiler, also significantly increases gas consumption. I will compare the gas consumption in the clocking mode with the gasoline consumption of the car. Consider that the gas consumption during clocking is driving in city traffic jams in terms of fuel consumption. And the continuous operation of the boiler is driving along a free highway in terms of fuel consumption.
The fact is that the boiler processor contains a program that allows the boiler, using the sensors built into it, to indirectly measure the thermal power consumed by the heating system. And adjust the generated power to this need. But this boiler takes from 15 to 40 minutes, depending on the capacity of the system. And in the process of adjusting its power, it does not work in the optimal mode in terms of gas consumption. Immediately after switching on, the boiler modulates maximum power and only over time, gradually by the approximation method, it reaches the optimal gas flow rate. It turns out that when the boiler cycles more than 30-40 minutes, it does not have enough time to reach the optimal mode and gas flow. Indeed, with the beginning of a new cycle, the boiler begins the selection of power and mode again.
To eliminate the clocking of the boiler, it is installed room thermostat. It is better to install it on the first floor in the middle of the house and if there is a heater in the room where it is installed, then the IR radiation of this heater should reach the room thermostat at a minimum. Also on this heater, a thermoelement (thermal head) on a thermostatic valve should not be installed.
Many boilers are already equipped with a remote control panel. Inside this control panel is the room thermostat. Moreover, it is electronic and programmable according to the time zones of the day and the days of the week. Programming the temperature in the house by time of day, by day of the week, and when you leave for a few days, also allows you to save a lot on gas consumption. Instead of a removable control panel, a decorative cap is installed on the boiler. For example, I will give a photo of the Baxi Luna 3 Komfort removable control panel installed in the hall of the first floor of the house, and a photo of the same boiler installed in the boiler room attached to the house with a decorative plug installed instead of the control panel.
6. Use of a greater share of radiant heat in heating devices.
You can also save any fuel, not just gas, by using heaters with a greater proportion of radiant heat.
This is explained by the fact that a person does not have the ability to feel exactly the temperature. environment. A person can only feel the balance between the amount of heat received and given off, but not the temperature. Example. If we take an aluminum blank with a temperature of +30 degrees, it will seem cold to us. If we pick up a piece of foam plastic with a temperature of -20 degrees, then it will seem warm to us.
With regard to the environment in which a person is located, in the absence of drafts, a person does not feel the temperature of the surrounding air. But only the temperature of the surrounding surfaces. Walls, floors, ceilings, furniture. I will give examples.
Example 1. When you go down to the cellar, after a few seconds you become chilly. But this is not because the air temperature in the cellar, for example, is +5 degrees (after all, air in a stationary state is the best heat insulator, and you could not freeze from heat exchange with air). And from the fact that the balance of the interchange of radiant heat with the surrounding surfaces has changed (your body has an average surface temperature of +36 degrees, and the cellar has an average surface temperature of +5 degrees). You begin to give off much more radiant heat than you receive. That's why you get cold.
Example 2. When you are in a foundry or steel shop (or just near a large fire), you get hot. But this is not because the air temperature is high. In winter, with partially broken windows in the foundry, the air temperature in the shop can be -10 degrees. But you are still very hot. Why? Of course, the air temperature has nothing to do with it. The high temperature of the surfaces, not the air, changes the balance of radiant heat transfer between your body and the environment. You begin to receive much more heat than you radiate. Therefore, people working in foundries and steel-smelting shops are forced to put on cotton trousers, padded jackets and hats with earflaps. To protect not from the cold, but from too much radiant heat. To avoid heatstroke.
From this we draw a conclusion that many modern heating specialists do not realize. That it is necessary to heat the surfaces surrounding a person, but not the air. When we heat only the air, first the air rises to the ceiling, and only then, descending, the air heats the walls and the floor due to the convective circulation of air in the room. Those. at first warm air rises to the ceiling, heating it, then descends to the floor along the far side of the room (and only then does the floor surface begin to heat up) and then in a circle. With this purely convective method of space heating, there is an uncomfortable temperature distribution throughout the room. When is the most heat indoors at head level, medium at waist level, and lowest at leg level. But you probably remember the proverb: "Keep your head cold and your feet warm!".
It is no coincidence that the SNIP states that in a comfortable home, the temperature of the surfaces of the outer walls and floor should not be lower than the average temperature in the room by more than 4 degrees. Otherwise, there is an effect that is both hot and stuffy, but at the same time chilly (including on the legs). It turns out that in such a house you need to live "in shorts and felt boots."
So, from afar, I was forced to lead you to the realization of which heating devices are best used in the house, not only for comfort, but also for fuel economy. Of course, heaters, as you may have guessed, must be used with the greatest proportion of radiant heat. Let's see which heating appliances give us the largest share of radiant heat.
Perhaps, such heating devices include the so-called "warm floors", as well as " warm walls(which are gaining more and more popularity). But even among the usually most common heating appliances, steel panel radiators, tubular radiators and cast iron radiators. I have to assume that steel panel radiators provide the largest share of radiant heat, since manufacturers of such radiators indicate the share of radiant heat, while manufacturers of tubular and cast-iron radiators keep this secret. I also want to say that aluminum and bimetallic "radiators" that have recently received aluminum and bimetallic "radiators" do not have the right to be called radiators at all. They are called so only because they are the same sectional as cast-iron radiators. That is, they are called "radiators" simply "by inertia." But according to the principle of their action, aluminum and bimetal radiators should be classified as convectors, not radiators. Since the share of radiant heat they have is less than 4-5%.
At the panel steel radiators the proportion of radiant heat varies from 50% to 15% depending on the type. The largest share of radiant heat is in type 10 panel radiators, in which the share of radiant heat is 50%. Type 11 has 30% radiant heat. Type 22 has 20% radiant heat. Type 33 has 15% radiant heat. There are also steel panel radiators produced using the so-called X2 technology, for example, from Kermi. It represents type 22 radiators, in which it passes first along the front plane of the radiator, and only then along the rear plane. Due to this, the temperature of the front plane of the radiator increases relative to the rear plane, and, consequently, the share of radiant heat, since only IR radiation from the front plane enters the room.
The respected firm Kermi claims that when using radiators made using X2 technology, fuel consumption is reduced by at least 6%. Of course, he personally did not have the opportunity to confirm or refute these figures in laboratory conditions, but based on the laws of thermal physics, the use of such technology really saves fuel.
Conclusions. I advise you to use steel panel radiators in the entire width of the window opening in a private house or cottage, in descending order of preference by type: 10, 11, 21, 22, 33. When the amount of heat loss in the room, as well as the width of the window opening and the height of the window sill do not allow using types 10 and 11 (not enough power) and the use of types 21 and 22 is required, then if there is a financial opportunity, I will advise you to use not the usual types 21 and 22, but using the X2 technology. Unless, of course, the use of X2 technology pays off in your case.
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The efficiency of the heating system depends on many factors. These include the rated power, the degree of heat transfer of radiators and the temperature regime of operation. For the latter indicator, it is important to choose the right degree of heating of the coolant. Therefore, it is necessary to determine the optimal temperature in the heating system for water, radiators and the boiler.
What determines the temperature of the water in the heating
For correct operation heat supply requires a graph of the temperature of the water in the heating system. According to it, the optimal degree of heating of the coolant is determined depending on the influence of certain external factors. It can be used to determine what water temperature in the heating batteries should be in a certain period of time the system is running.
It is a common misconception that the higher the degree of heating of the coolant, the better. However, this increases fuel consumption, increasing operating costs.
Often, the low temperature of the radiators is not a violation of the norms for heating the room. A low-temperature heat supply system was simply designed. That is why the exact calculation of water heating should be given Special attention.
Optimum temperature water in heating pipes largely depends on external factors. To determine it, the following parameters must be taken into account:
- Heat loss at home. They are decisive for the calculation of any type of heat supply. Their calculation will be the first stage in the design of heat supply;
- Boiler characteristics. If the operation of this component does not meet the design requirements, the water temperature in the heating system of a private house will not rise to the desired level;
- Material for the manufacture of pipes and radiators. In the first case, it is necessary to use pipes with a minimum thermal conductivity. This will reduce heat loss in the system during the transportation of the coolant from the boiler heat exchanger to the radiators. For batteries, the opposite is important - high thermal conductivity. Therefore, the temperature of the water in the radiators central heating, made of cast iron, should be slightly higher than that of aluminum or bimetallic structures.
Is it possible to independently determine what temperature should be in the radiators? It depends on the characteristics of the system components. To do this, you should familiarize yourself with the properties of the batteries, the boiler and the heat supply pipes.
IN centralized system heat supply temperature of the heating pipes in the apartment is not an important indicator. It is important that the norms for heating the air in living rooms.
Heating standards in apartments and houses
In fact, the degree of water heating in pipes and heat supply radiators is a subjective indicator. It is much more important to know the heat dissipation of the system. It, in turn, depends on the minimum and Maximum temperature water in the heating system can be reached during operation.
For autonomous heat supply, the norms of central heating are quite applicable. They are detailed in the resolution of the PRF No. 354. It is noteworthy that the minimum water temperature in the heating system is not indicated there.
It is only important to observe the degree of heating of the air in the room. Therefore, in principle, the temperature regime of operation of one system can be different from another. It all depends on the influencing factors that were mentioned above.
In order to determine what temperature should be in the heating pipes, you should familiarize yourself with the current standards. In their content there is a division into residential and non-residential premises, as well as the dependence of the degree of air heating on the time of day:
- In rooms during the daytime. In this case, the standard heating temperature in the apartment should be +18°C for rooms in the middle of the house and +20°C in the corners;
- In living rooms at night. Some reduction is allowed. But at the same time, the temperature of the heating radiators in the apartment should provide, respectively, + 15 ° С and + 17 ° С.
Responsible for compliance with these standards Management Company. In case of their violation, you can request a recalculation of payment for heating services. For autonomous heat supply, a table of temperatures for heating is made, where the values \u200b\u200bof the heating of the coolant and the degree of load on the system are entered. At the same time, no one bears responsibility for violation of this schedule. This will affect the comfort of staying in a private house.
For centralized heating, it is mandatory to maintain the required level of air heating in stairwells and non-residential premises. The water temperature in the radiators must be such that the air is heated to a minimum value of +12°C.
Calculation of the temperature regime of heating
When calculating the heat supply, the properties of all components must be taken into account. This is especially true for radiators. What is the optimal temperature in the radiators - + 70 ° C or + 95 ° C? It all depends on the thermal calculation, which is performed at the design stage.
First you need to determine the heat loss in the building. Based on the data obtained, a boiler with the appropriate power is selected. Then comes the most difficult design stage - determining the parameters of heat supply batteries.
They must have a certain level of heat transfer, which will affect the temperature curve of the water in the heating system. Manufacturers indicate this parameter, but only for a certain mode of operation of the system.
If you need to spend 2 kW of thermal energy to maintain a comfortable level of air heating in a room, then the radiators must have no less heat transfer.
To determine this, you need to know the following quantities:
- Permissible maximum water temperature in the heating system -t1. It depends on the power of the boiler, temperature limit impact on pipes (especially polymer);
- Optimal the temperature that should be in the heating return pipes - t This is determined by the type of wiring of the mains (one-pipe or two-pipe) and the total length of the system;
- Required degree of air heating in the room -t.
Tnap=(t1-t2)*((t1-t2)/2-t3)
Q=k*F*Tnap
Where k- heat transfer coefficient of the heating device. This parameter must be specified in the passport; F- radiator area; Tnap- thermal pressure.
By varying the various indicators of the maximum and minimum water temperatures in the heating system, you can determine the optimal mode of operation of the system. It is important to correctly initially calculate the required power of the heater. Most often, the indicator of low temperature in heating batteries is associated with heating design errors. Experts recommend adding a small margin to the obtained value of the radiator power - about 5%. This will be needed in case of a critical decrease in the temperature outside in the winter.
Most manufacturers indicate the heat output of radiators according to the accepted standards EN 442 for mode 75/65/20. This corresponds to the norm of the heating temperature in the apartment.
Water temperature in the boiler and heating pipes
After performing the above calculation, it is necessary to adapt the heating temperature table for the boiler and pipes. During operation of the heat supply, there should not be any emergencies, common cause which is a violation of the temperature graph.
The normal indicator of water temperature in central heating batteries can be up to + 90 ° С. This is strictly monitored at the stage of preparation of the coolant, its transportation and distribution to residential apartments.
Much the situation is more complicated with autonomous heating. In this case, control completely depends on the owner of the house. It is important to ensure that there is no excess of water temperature in the heating pipes that goes beyond the schedule. This may affect the security of the system.
If the water temperature in the heating system of a private house exceeds the norm, the following situations may occur:
- Pipeline damage. This is especially true for polymer lines, in which the maximum heating can be + 85 ° C. That is why the normal value of the temperature of the heating pipes in an apartment is usually + 70 ° C. Otherwise, deformation of the line may occur and a rush will occur;
- Air heating excess. If the temperature of the heat supply radiators in the apartment provokes an increase in the degree of air heating above + 27 ° C - this is beyond the normal range;
- Reduced service life of heating components. This applies to both radiators and pipes. Over time, the maximum temperature of the water in the heating system will lead to breakdown.
Also, a violation of the schedule of water temperature in the system autonomous heating causes air pockets to form. This occurs due to the transition of the coolant from a liquid state to a gaseous state. Additionally, this affects the formation of corrosion on the surface of the metal components of the system. That is why it is necessary to accurately calculate what temperature should be in the heat supply batteries, taking into account their material of manufacture.
Most often, a violation of the thermal regime of operation is observed in solid fuel boilers. This is due to the problem of adjusting their power. When a critical temperature level in the heating pipes is reached, it is difficult to quickly reduce the boiler power.
The influence of temperature on the properties of the coolant
In addition to the above factors, the temperature of the water in the heat supply pipes affects its properties. This is the principle of operation of gravitational heating systems. With an increase in the level of heating of water, it expands and circulation occurs.
However, in the case of using antifreezes, the excess temperature in the radiators can lead to other results. Therefore, for heat supply with a coolant other than water, you must first find out the permissible indicators of its heating. This does not apply to the temperature of the radiators. district heating in the apartment, since antifreeze-based liquids are not used in such systems.
Antifreeze is used if there is a possibility of low temperature affecting the radiators. Unlike water, it does not begin to change from a liquid to a crystalline state when it reaches 0°C. However, if the work of heat supply is outside the norms of the temperature table for heating upwards, the following phenomena may occur:
- Foaming. This entails an increase in the volume of the coolant and, as a consequence, an increase in pressure. The reverse process will not be observed when the antifreeze cools;
- Formation limescale . The composition of antifreeze includes a certain amount of mineral components. If the norm of the heating temperature in the apartment is violated in a big way, their precipitation begins. Over time, this will lead to clogging of pipes and radiators;
- Increasing the density index. There may be malfunctions in the operation of the circulation pump if its rated power was not designed for the occurrence of such situations.
Therefore, it is much easier to monitor the temperature of the water in the heating system of a private house than to control the degree of heating of antifreeze. In addition, ethylene glycol-based compounds emit a gas harmful to humans during evaporation. Currently, they are practically not used as a coolant in autonomous systems heat supply.
Before pouring antifreeze into the heating, all rubber gaskets should be replaced with paranitic ones. This is due to the increased permeability of this type of coolant.
Ways to normalize the temperature regime of heating
The minimum value of the water temperature in the heating system is not the main threat to its operation. This, of course, affects the microclimate in residential premises, but in no way affects the functioning of heat supply. In case of excess of norm of heating of water there can be emergencies.
When drawing up a heating scheme, it is necessary to provide for a number of measures aimed at eliminating a critical increase in water temperature. First of all, this will lead to an increase in pressure and an increase in the load on inner surface pipes and radiators.
If this phenomenon is one-time and short-lived, the heat supply components may not be affected. However, such situations arise under the constant influence of certain factors. Most often, this is the incorrect operation of a solid fuel boiler.
- Installing a security group. It consists of an air vent, a bleed valve and a pressure gauge. If the water temperature reaches a critical level, these components will remove excess coolant, thereby ensuring the normal circulation of the liquid for its natural cooling;
- mixing unit. It connects the return and supply pipes. Additionally, a two-way valve with a servo drive is installed. The latter is connected to a temperature sensor. If the value of the degree of heating exceeds the norm, the valve will open and the flows of hot and cooled water will mix;
- Electronic heating control unit. It records the temperature of the water in various parts of the system. In case of violation of the thermal regime, he will give the appropriate command to the boiler processor to reduce power.
These measures will help prevent incorrect operation of the heating for another initial stage the occurrence of a problem. The most difficult thing is to regulate the level of water temperature in systems with a solid fuel boiler. Therefore, for them, special attention should be paid to the choice of parameters of the safety group and the mixing unit.
The effect of water temperature on its circulation in heating is described in detail in the video:
