Optimum operating mode of the heating boiler. Optimum boiler temperature Coolant temperature in gas boilers
Maintenance of a gas boiler with low productivity is expensive. Therefore, anyone who uses such a device wants to find optimal mode gas boiler operation, at which it will have the highest possible efficiency (efficiency) at minimal cost fuel. This problem becomes especially urgent in anticipation of the next heating season.
The performance of a gas boiler is influenced by various factors. If you haven't bought yet this device, but only plan to purchase it, please note that the main condition for its installation is the presence of a centralized gas supply. Some think they can get by bottled gas, but this will significantly increase costs. In this case, it is better to install electric heating.
Optimum performance depends on the following criteria:
- Boiler designs - they can be single-circuit, double-circuit, mounted, floor, etc.
- Efficiency - nominal and real.
- Proper organization of heating in the house: the power of the boiler must correspond to the area of \u200b\u200bthe heated premises.
- The technical condition of the equipment.
- Gas quality.
Now let's take a closer look at how each of the criteria can be optimized to maximize device performance.
Boiler design
Boilers are single-circuit and double-circuit. The first will have to buy a boiler indirect heating so that he can heat the water. The double-circuit version is preferable, as it is equipped with everything necessary for production hot water and home heating. For ease of use, the priority mode in such a boiler is the supply of hot water. This means that when the water supply is turned on, the heating stops.
There are wall and floor gas boilers. The former have less power and can only heat a room up to 300 m². If your house is larger, you will need to purchase another wall-hung or floor-standing boiler.
Nominal and real efficiency
The instructions for any gas boiler indicate the nominal efficiency, usually it is 92-95%, for condensing models - about 108%. However, the real figure is usually 9-10% lower. Further reduces its presence various kinds heat loss:
- Physical underburning - this indicator depends on the volume of excess air in the unit during the gas combustion process. It is also affected by the temperature of the flue gases: the higher it is, the lower the efficiency of the boiler.
- Chemical underburning - this indicator varies depending on the volume of oxide carbon monoxide that comes from the combustion of carbon.
- Heat loss that escapes through the walls of the boiler.
You can increase the actual efficiency of the device in the following ways:
- Reducing the physical underburning rate by regularly cleaning soot on the pipeline and removing scale from the water circuit.
- Reducing the amount of excess air by installing a draft limiter on the chimney.
- By adjusting the position of the blower damper in such a way that the maximum temperature of the coolant is reached.
- Regular cleaning of soot on the combustion chamber, due to which gas consumption increases.
To increase the efficiency of a gas boiler will allow replacing the chimney with a more innovative one. Most of the traditional branch pipes are too dependent on weather conditions. Came to replace them coaxial chimney, which is resistant to temperature extremes and is able to increase efficiency, as well as save fuel.
Note! Some owners of gas boilers make a mistake - they pour out the coolant and pour in tap water. This is not worth doing, as new plumbing water, when heated, leaves scale on the walls of the pipeline.How to properly organize home heating with a gas boiler?
Matching the power of the heating boiler to the heated area of the room is a key factor in the quality of heating. This factor also affects the duration of uninterrupted operation of the unit.
To accurately calculate required power boiler for the house, you should take into account the features of the structure, possible heat losses through walls and ceilings. It is quite difficult to make these calculations on your own, so it is better to hire a specialist who can correctly determine the optimal boiler power.Usually, 100 W of power per 1 m² is enough to heat a house built in accordance with all building codes. Based on this rule, we get the following table.
When buying gas boilers, it is better to give preference to modern foreign-made models, since their quality is higher compared to domestic ones. Also, more "advanced" units have additional functions settings with which you can choose the optimal mode of operation of the gas boiler.
Note! When choosing a gas boiler, it should be noted that its optimal power should be 70-75% of the maximum.Below is a video showing how to install optimal wall boiler mode.
Technical condition of the boiler
From technical condition gas boiler directly depends on its performance. In order for it to last as long as possible and work optimally, regular maintenance is necessary. It is important to clean the internal elements from soot and scale in a timely manner.
A frequent problem of a gas boiler, in which its performance decreases, is clocking. This means that the unit turns on too often due to excessive heating of the coolant. This usually occurs due to too much power of the device. Clocking leads to excessive consumption of gas and rapid wear of equipment. solved this problem very simple - you should set the gas supply level to the minimum. You can do this by following the attached instructions.
Gas quality
The quality of the gas is the only factor that we cannot influence. An increased volume of moisture leads to an increase in gas consumption.
How to set the optimal mode?
There is such a thing as the optimal mode of a gas boiler. As mentioned above, the unit consumes fuel economically if it operates at 75% of maximum power. Most boilers are set to the temperature of the coolant. When it reaches the required value, the boiler turns off for a while. The user can determine which optimum operating temperature of the gas boiler it will suit you and install it. The value may change depending on weather conditions, for example, in winter the temperature of the coolant should be 70-80°C, and in spring or autumn it can be reduced to 55-70°C.
Modern models of gas boilers are equipped with temperature sensors, thermostats and automatic system mode settings. If your boiler does not have such equipment, it can be purchased at a specialized store and installed on almost any model. Using the thermostat, you can set the desired temperature in the room, which the gas boiler must maintain. Depending on it, the coolant will heat up and cool down at a certain frequency. This mode of operation provides for the automatic reaction of the boiler to temperature changes in the street or in the house. In addition, at night it is advisable to reduce the heat in the room by 1-2 ° C. Thus, automation will minimize gas consumption, and at the same time maintain the temperature in the room at the desired level. Note! Installing sensors and a thermostat will save up to 20% of gas.Some modern models boilers can change the mode of operation depending on the presence of people in the room. This makes it possible to maintain the optimum temperature at prolonged absence hosts. But still, it is not worth leaving the boiler in working condition for a long time unattended. Otherwise, when emergency shutdown electricity, the unit may fail.
If you find it difficult to independently reconfigure or adjust the operation of your gas boiler, contact the specialists.
The most economical boilers
Statistics and specifications indicate that gas boilers foreign manufacturers have the highest efficiency. Manufacturers Baxi, Protherm, Buderus, Bosch have proven themselves well on the market.
If you haven't made your choice yet, take a look at condensing boilers- its efficiency is higher than that of traditional ones by 10-11%, they are the most economical and powerful, but they are also not cheap. But low fuel consumption and long term services will pay for the money spent on it. Its principle of operation is different in that the products of fuel combustion do not escape in the form of gas, but pass through a stainless steel heat exchanger, heat water, cool down and fall out in the form of liquid condensate.
To achieve optimal performance gas boiler, it should be maintained in good condition, regularly cleaned of soot and scale, and equipped with an automatic room temperature control system. If you follow these recommendations, your unit will enjoy uninterrupted operation, low gas consumption and a cozy atmosphere in the house.
External low-temperature corrosion occurs as a result of the formation of drops or a film of moisture on the heating surfaces and reacts with the metal surface.
Moisture appears on the heating surfaces during the condensation of water vapor from flue gases due to the low temperature of the water (air) and, accordingly, the low temperature of the wall.
The dew point temperature at which water vapor condenses depends on the type of fuel being burned, its moisture content, excess air coefficient, and the value of the partial pressure of water vapor in the combustion products.
It is possible to exclude the occurrence of low-temperature corrosion on heating surfaces when the surface temperature on the side of the gaseous medium is 5°C higher than the dew point temperature. This value of the dew point temperature corresponds to the condensation temperature of pure water vapor and appears during fuel combustion.
When fuel (fuel oil) that contains sulfur is burned, sulfuric anhydride is formed in the combustion products. Part of this gas, oxidized, forms aggressive sulfuric anhydride, which, dissolving in water, forms a film of sulfuric acid solution on the heating surfaces, as a result, the corrosion process sharply intensifies. The presence of sulfuric acid vapors in the combustion products increases the dew point temperature and causes corrosion in those areas of the heating surface, the temperature of which is much higher than the dew point temperature and when burning natural gas is 55 ° C, when burning fuel oil - 125 ... 150 ° C.
In steam boilers, in most cases, the temperature of the water entering the economizer exceeds the required temperature because the water comes from atmospheric deaerators with a temperature of 102 ° C.
This issue is more difficult to solve for hot water boilers, since the temperature of the coolant in the external pipeline of the heat supply system entering the boilers depends on the outside air temperature.
It is possible to increase the temperature of the incoming water to the boiler by recirculating hot water from the boiler.
The efficiency and reliability of the water heating system of a water boiler depends on the flow rate of the coolant through the recirculation. With an increase in pumping, the temperature of the water entering the boiler increases, the temperature of the exhaust gases also increases, which means that the efficiency of the boiler decreases. The power consumption for the drive of the recirculation pump in this case increases.
Operating instructions for hot water boilers propose to regulate the operation of the heating water heating system in such a way that the temperature of the water at the inlet to the boilers during the combustion of natural gas does not fall below 60 ° C. This requirement reduces the efficiency of their operation, since anti-corrosion measures to maintain the temperature of the walls of the heating surfaces can be provided if the temperature is below 60 ° C. But in this case, it is necessary to take into account the temperature of the walls of the heating surface in the calculations.
An analysis of such calculations shows that, for example, for hot water boilers operating on natural gas, at a gas temperature of 140 ° C, the water temperature at the inlet to the boiler must be maintained at least 40 ° C, i.e. below 60°C as suggested by the instructions.
Thus, by changing the mode of operation of hot water boilers, it is possible to save heat and electrical energy in the absence of low-temperature corrosion of metal surfaces of hot water boilers.
After installing the heating system, it is necessary to adjust temperature regime. This procedure must be carried out in accordance with existing standards.
The requirements for the temperature of the coolant are set out in normative documents that establish the design, installation and use engineering systems residential and public buildings. They are described in the State building codes and rules:
- DBN (B. 2.5-39 Heat networks);
- SNiP 2.04.05 "Heating, ventilation and air conditioning".
For the calculated temperature of the water in the supply, the figure is taken that is equal to the temperature of the water at the outlet of the boiler, according to its passport data.
For individual heating to decide what should be the temperature of the coolant, should be taking into account such factors:
- The beginning and end of the heating season according to the average daily temperature outside +8 ° C for 3 days;
- The average temperature inside the heated premises of housing and communal and public importance should be 20 ° C, and for industrial buildings 16°C;
- The average design temperature must comply with the requirements of DBN V.2.2-10, DBN V.2.2.-4, DSanPiN 5.5.2.008, SP No. 3231-85.
According to SNiP 2.04.05 "Heating, ventilation and air conditioning" (clause 3.20), the coolant limit values are as follows:
Depending on the external factors, the water temperature in the heating system can be from 30 to 90 °C. When heated above 90 ° C, dust begins to decompose and paintwork. For these reasons, sanitary standards prohibit more heating.
To calculate the optimal indicators, special graphs and tables can be used, in which the norms are determined depending on the season:
- With an average value outside the window of 0 °С, the supply for radiators with different wiring is set at a level of 40 to 45 °С, and the return temperature is from 35 to 38 °С;
- At -20 °С, the supply is heated from 67 to 77 °С, while the return rate should be from 53 to 55 °С;
- At -40 ° C outside the window for all heating devices set the maximum allowable values. At the supply it is from 95 to 105 ° C, and at the return - 70 ° C.
Optimal values in an individual heating system
H2_2Heating system helps to avoid many problems that arise with a centralized network, and the optimal temperature of the coolant can be adjusted according to the season. In the case of individual heating, the concept of norm includes the heat transfer of a heating device per unit area of the room where this device is located. The thermal regime in this situation is provided design features heating appliances.
It is important to ensure that the heat carrier in the network does not cool below 70 °C. 80 °C is considered optimal. FROM gas boiler it is easier to control heating, because manufacturers limit the possibility of heating the coolant to 90 ° C. Using sensors to adjust the gas supply, the heating of the coolant can be controlled.
It is a little more difficult with solid fuel devices, they do not regulate the heating of the liquid, and can easily turn it into steam. And it is impossible to reduce the heat from coal or wood by turning the knob in such a situation. At the same time, the control of heating of the coolant is rather conditional with high errors and is performed by rotary thermostats and mechanical dampers.
Electric boilers allow you to smoothly adjust the heating of the coolant from 30 to 90 ° C. They are equipped with an excellent overheating protection system.
One-pipe and two-pipe lines
The design features of a single-pipe and two-pipe heating network determine different norms for heating the coolant.
For example, for a single-pipe line, the maximum rate is 105 ° C, and for a two-pipe line - 95 ° C, while the difference between the return and supply should be, respectively: 105 - 70 ° C and 95 - 70 ° C.
Matching the temperature of the heat carrier and the boiler
Regulators help to coordinate the temperature of the coolant and the boiler. These are devices that create automatic control and correction of the return and supply temperatures.
The return temperature depends on the amount of liquid passing through it. The regulators cover the liquid supply and increase the difference between the return and supply to the level that is needed, and the necessary pointers are installed on the sensor.
If it is necessary to increase the flow, then a boost pump can be added to the network, which is controlled by a regulator. To reduce the heating of the supply, a “cold start” is used: that part of the liquid that has passed through the network is again transferred from the return to the inlet.
The regulator redistributes the supply and return flows according to the data taken by the sensor, and ensures strict temperature norms heating networks.
Ways to reduce heat loss
The above information can be used to correct calculation coolant temperature standards and tell you how to determine the situation when you need to use the regulator.
But it is important to remember that the temperature in the room is affected not only by the temperature of the coolant, outdoor air and wind strength. The degree of insulation of the facade, doors and windows in the house should also be taken into account.
To reduce the heat loss of housing, you need to worry about its maximum thermal insulation. Insulated walls, sealed doors, metal-plastic windows help reduce heat loss. It will also reduce heating costs.
