Regulation of heat consumption of buildings - real heat savings. Weather control with mixing valve
Regulation of the heating system implies bringing the process of consumption of thermal energy in line with the real needs for it. A simple example: the colder it is outside, the more intensively the heating system should work and, conversely, when the air temperature in the house rises above the limit value, the temperature of the coolant in the heating devices should decrease.
The easiest way to regulate the heating system is to manually control the operation of the boiler and heating devices: it is hot in the house, you can turn off the coolant supply valve to the heating device, as a result of which return water will return to the boiler hot, which will lead to the shutdown of the boiler or to a decrease in fuel consumption.
An even simpler way to regulate the heating system is to temporarily turn off the boiler and turn it on when the room temperature drops. To date, similar manual control» is outdated and it is possible to talk about it only in relation to heating appliances that do not have automatic control systems, for example, to wood stoves or to some types of wood-burning heating boilers.
Modern heating control systems solve two problems simultaneously:
allow you to create really comfortable conditions in the house, maintaining a predetermined temperature level in it
optimize fuel consumption and, as a result, reduce heating costs
The heating system is adjusted according to one of two parameters
Outdoor temperature
Indoor temperature
It is believed that more comfortable conditions in a private house can be obtained by changing the temperature of the coolant, depending on the conditions inside the room. This is explained simply: heat loss do not always linearly depend on the outside temperature: it is necessary to take into account the wind speed and the location of the building relative to the cardinal points.
For apartment buildings and systems central heating more important is the outdoor air temperature, which makes it possible to obtain averaged results immediately for all consumers of thermal energy.
Methods for regulating heating systems
As mentioned above, the main task of regulating the heating system is to maintain a certain temperature level in the room. You can do this in several ways:
By changing the speed of movement of the coolant through the heating device using stop valves or with a circulation pump. In this case, there is a change in the amount of coolant passing through the heating device per unit of time. This method is called quantitative.
By changing the heating temperature of the coolant (changing its quality). This method is called qualitative.
It should be noted that both methods are inextricably linked with each other and in systems High Quality are used at the same time.
Practical implementation of method No. 1
The easiest way to control heating is to change the operating modes of the circulation pump depending on the temperature in the room: it is cold, the pump operates at maximum speed, which ensures the most intense heat transfer from heating devices. It became hot: the coolant movement speed is minimal. At night or during the day, when all residents of the house are at work or at school, a heat saving mode can also be used, which provides for a minimum water flow rate in heating system.
The disadvantage of heating control with a circulation pump is general approach to all rooms in the house, regardless of the actual need for thermal energy.
More accurate, local regulation of the heating system can be obtained by controlling the operation of a single radiator.
How to control the operation of a heating radiator?
In practice, it is possible to change the flow rate of the coolant using automatic heads, the design of which includes a valve and a temperature sensor that responds to changes in the temperature in the room. The principle of operation of the device is quite simple: the head cavity is filled with liquid, the volume of which depends on temperature: when it gets cold, the volume of liquid decreases, the valve opens, while increasing the flow rate of the coolant. With an increase in the temperature in the room, on the contrary: the volume of liquid increases, the valve closes, blocking the movement of the coolant.
The disadvantage of automatic heads is their low reliability and frequent failure. More perfect and reliable is the method of heating control using a servo driven and blocking the supply of coolant to the radiator, also depending on the temperature in the room.
Both the automatic head and the servo drive are designed to change the temperature of the coolant not in the entire heating system, but only in one individual radiator. If there are several heaters in the room, each of them will have to be equipped with such automatic control systems. Only in this case can you really regulate the heating.
All heating devices in the house can be combined into one system automatic control heating.
Adjustment during operation
There is also another way - operational regulation. As the name implies, the heating system is regulated while it is running. This is necessary to make adjustments as needed. For example, if there is a need to increase or decrease the amount of heat (depending on the air temperature outside and meteorological conditions). The change in the amount of heat generated by the system is provided by adjusting the temperature or by changing the flow rate of the coolant. Thus, it can be conditionally divided into "qualitative" and "quantitative" options for monitoring the system.
Quality regulation carried out directly at the thermal station. There are local and group. Quantitative has three divisions: group, individual and local.
This method of controlling the system is carried out manually using valves and taps, and automatically when the air temperature in the apartment changes. In branched systems, it is necessary to change the coolant flow rate - this should simplify the adjustment task.
In private homes, it requires knowledge about the features of individual water heating. The main task of the system is to provide optimal microclimate for the whole family. Unfortunately, quite often heating gets out of control. Most often, incorrect operation and untimely adjustment of parameters lead to inefficiency of indicators. The reasons may also be errors made in the design of heating, or poor insulation.
As practice shows, during the heating system, people do not ask themselves the question of calculations. Installation specialists prefer to do everything quickly, due to which accuracy suffers. As a result, it can be cool in one room and too hot in another. Comfort in this case can not be expected.
When assessing the quality of the system and the efficiency of its operation, all parameters and features of your heating should be taken into account. Regardless of the power source (electric boiler or gas), the system must work smoothly, so proper regulation is the key to a warm and comfortable home.
The easiest way to regulate water circulation is to use thermostat located on the boiler. It's kind of lever device, which will allow you to switch heat costs and in this way there will be a decrease in temperature in the house. Also, if necessary, you can increase the level of heating of the liquid and thereby increase the air temperature in the house.
O.F. Gavey, engineer, JSC "Magnitogorsk Iron and Steel Works", Magnitogorsk;
d.t.s. IN AND. Panferov, Professor, Research Institute "South Ural State University”, Chelyabinsk
At present, many industrial enterprises in heat supply systems, low-temperature heat supply control schedules are used instead of traditional high-temperature ones. It is believed that the low-temperature parameters of the coolant are more preferable due to the reduced fuel consumption for the production of thermal energy, low heat losses during the generation of thermal energy and transportation of the coolant, advanced level comfort for consumers, etc. It is known that for the competent transfer of heat supply systems from one parameter to another, it is necessary to change the diameters of heat networks and network hardware, as well as to develop suitable methods of heat regulation with new temperature curves.
As for the last statement, today there are many automation tools that help to carry out competent adjustment of heat supply systems at the enterprise. Changing the diameters of heat pipelines and replacing equipment in heat networks are expensive and time-consuming measures that do not bring economic benefits, therefore, often heat supply organizations and companies producing thermal energy tend to avoid them. This is justified by the fact that heating network are designed with a large margin, both in terms of strength and diameter, therefore, when the temperature of the coolant decreases, its amount increases without any changes in the configuration of heating networks.
In this case, as a rule, it is not known whether such an increase in the amount of coolant is sufficient to provide a given heat flux at reduced temperatures, whether the safety margin of heat pipelines is sufficient, etc. Therefore, the determination of the dependences of the main parameters of heat supply - the flow rate and the temperature of the heat carrier - from each other is an interesting task from this point of view. Knowing how the coolant flow rate changes when the temperature graph changes and vice versa, one can judge the amount of heat loss during the transportation of the coolant, the optimal diameters of the heat pipes, the flow rate electrical energy for coolant pumping, allowable thickness of thermal insulation of heat pipelines, etc. The data obtained can be used both to assess the state of already existing systems heat supply, and at the stage of their design.
As the main idea in the development of dependences, it was assumed that the temperature and flow rate of the heat carrier in the supply heat pipeline, the diameters of the heat pipelines and heat losses at the initial temperature curve are equal to t, G, D and q, respectively. After changing the temperature graph, the same parameters are equal to t+∆t, G+∆G, D+∆D, q+∆q, respectively. The amount of thermal energy transferred by the system Q must be unchanged at any temperature parameters.
1. Change in the flow rate of the coolant with a change in its temperature.
At the initial stage of the study, the task was to determine how a decrease in the temperature of the coolant should affect an increase in its flow so that the delivered thermal power(the heat flux delivered by the coolant) would be the same. As a result of solving this problem, an algorithm for controlling the coolant flow was developed, taking into account the characteristics of heat-consuming equipment, which has the form:
where KF is the product of the heat transfer coefficient and the surface area of an equivalent heating device, W / O С; G - coolant flow rate for the previous (basic) heat supply mode, kg/s; ∆G - required change in coolant flow rate for low-temperature regime, kg/s; t ext, t, ∆t - the temperature of the internal air of the heat supply object, the temperature of the heat carrier in the supply heat pipeline in the base mode and the change in the temperature of the heat carrier during low-temperature heat supply, respectively, ° С; c is the specific heat capacity of the coolant, kJ/(kg О С); G+∆G- required flow coolant in the new mode of heat supply.
It should be emphasized that the product KF is a thermotechnical indicator of the object's heating system and shows how much heat the object is able to receive from the heat supply system. For convenience, the entire heating system of the building is taken as the equivalent heating device.
Most often, the product KF is determined with a statistical set of actual data from heat meters and its subsequent calculation by the least squares method.
For clarity of the obtained results, Fig. 1 shows a graph of the dependence of the change in the flow rate of the coolant on the change in the temperature of the coolant.
This graph shows the change in the flow rate of the coolant depending on the change in its temperature, taking into account the properties of the heat-consuming object for following conditions: t=150 О С, KF=7000 W/ О С, t ext=20 0 С. , 13.1, 30.2, 53.4, 86.7, 138.3% respectively.
2. Change in diameters when the temperature of the coolant changes.
At the next stage of the study, it was revealed how the diameters of the heat pipelines should change so that when another (off-design) flow is pumped through the heat networks, the pressure loss remains the same.
The dependence that makes it possible to estimate the change in the diameters of heat pipes due to changes in the temperature of the coolant (the heat-consuming characteristics of the object are taken into account) looks like in the following way:
The results of solving this problem are illustrated in fig. 2, in particular, for the case of a decrease in the temperature of the heat carrier in the supply heat pipeline from 150 ° C to 95 ° C, it is necessary to increase the diameter of the heating main by 23%.
It should be noted that the change in diameter by the indicated values occurs under the condition of constant specific pressure losses due to friction. In some cases, when initially the diameter of the heat networks is selected with a certain margin of safety, and the specific pressure losses are not limiting, the optimal diameter of the heat network with temperature changes may differ from that obtained from the dependence.
3. Change in heat loss with a change in the temperature of the coolant.
The next task was to determine the change in heat losses and power consumption for pumping the coolant with a decrease in its temperature and a change in the diameter of insulated heat pipes.
The final dependency looks like this:
where q is the linear density heat flow, with thermal losses, W; Δq - change in the linear density of the heat flux, W; t nar - outdoor air temperature, О С.
To simplify function (3), the following designations are introduced: Δq/q=y; Δt/t=х;
1 - (t nar / t) \u003d a.
Then the last dependence will be rewritten in the form:
Let the coolant temperature be 150 °C, and the outside air temperature be minus 34 °C, then a = 1.23. For these conditions, the graph of the dependence of the change in the linear density of the heat flux on the change in the coolant temperature is shown in fig. 3. The resulting graph shows that with a decrease in the temperature of the coolant, the value of heat losses decreases. Theoretically, with a significant decrease in temperature, heat losses begin to increase due to a significant increase in the surface area of heat pipes, as evidenced by the extremum of the graph.
The obtained relations allow to determine the change in the main parameters of the heat network - diameter, flow, linear density of the heat flow - from the change in the temperature of the coolant and, as a result, to evaluate the cost of measures to transfer systems to low-temperature heat supply and can be used in the formation of criteria for decision-making.
Literature
1. Gershkovich V.F. One hundred and fifty .. Norm or bust? (Reflections on the parameters of the coolant) // Energy saving. 2005. No. 5. S. 14-19.
2. Sharapov V.I., Rotov P.V. Load regulation of heat supply systems //M.: News of heat supply, 2007. - 164 p.
3. // News of heat supply. 2007. No. 2. S. 30-35.
To date, the potential for the development of traditional heat supply systems in terms of increasing heat transfer without significant material costs is almost exhausted. In them, the maximum efficiency is quite fully chosen through the use of modern heat-using equipment, electronic means regulation and control of consumption and distribution of thermal energy and heat carrier. Replacement of shell-and-tube water heaters with lamellar ones was a significant step towards increasing the turbulence of the coolant flow, and, consequently, increasing heat transfer. On the one hand, this made it possible to increase the heat transfer coefficient within 10%, and on the other hand, the tendency to overgrowing, the formation of scale, sludge and other deposits increased, which eventually leads to a decrease in the heat transfer coefficient and increased costs for transporting the coolant. A survey of management companies in the region showed that flushing of heat supply systems with plate heat exchangers DHW is spent up to 200 thousand rubles annually. And in budgetary organizations, due to improper operation due to further unsuitability, heat exchangers are replaced with new ones without even having worked out the regulated resource.
One of the cardinal ways to solve this problem is to transfer the coolant circulation in the heat supply system from a stationary mode to a pulsed one. In this case, several effects can be used. Firstly, the heat transfer coefficient increases (from 10 to 150%) of the moving flow, depending on the frequency and amplitude of the pulsations of its outflow velocity, secondly, self-cleaning of the heat transfer surfaces of the equipment is realized, and thirdly, it becomes possible to use the momentum momentum of the coolant, for example, to transform a part of the available pressure of the heating coolant into the pressure of the heated one in the case independent accession heating installations or for circulating water in a hot water system.
Conducted experimental studies showed that the use of pulsed coolant supply technology will guarantee to obtain:
- decline specific consumption fuel at the heat source due to the most improved heat removal by 5 - 30%;
- Increasing the service life of the heat-using equipment of the heating point by at least 2 times;
- Reduced requirements for the quality of network water;
- Reduction of heat transfer surfaces of heat-using equipment due to an increase in the heat transfer coefficient in pulsating mode by 1.3 - 2 or more times;
- Reducing material costs for the design and installation of a heating point and a heat supply system as a whole by reducing its total metal consumption.
- Reducing the cost of transporting the coolant and thermal energy in the heat consumption system when the available pressure of the high-temperature coolant of the heating network is transformed into the pressure of the low-temperature coolant of the heat consumption system.
- Relative ease of implementation of the pulsating mode.
The ability to create a significant (10 atm or more) available pressure, which is necessary for high-rise buildings, without the use of booster pumps.
As a result of the implementation of the project, it is expected to increase the energy efficiency of heat and power equipment of heat supply systems by at least 1.5 times in the traditional heat supply system and by more than 2.5 times when using new heat and power devices adapted to the pulsed method of supplying heat carrier.
The efficiency of modern heating is ensured by the controllability of the system and the heat generator, weather-dependent regulation, the ability to program temperature conditions and maintain them separately for different rooms, remote control, and coordinated operation of heat sources.
You can subscribe to articles at
Today, the owners of individual houses are making ever higher demands on the efficiency of heating systems, their ability to provide a comfortable temperature in the premises, and ease of use. The article formulates and discloses the basic principles of creating efficient heating using the equipment offered by the modern market.
Efficiency modern heating provide: controllability of the system and the heat generating plant, weather-compensated regulation, the ability to program the change temperature conditions(thermostating), implement them independently for different rooms, remote control, minimizing the thermal inertia of the system. Coordinated work is also required various sources heat, high- and low temperature heating, DHW.
Consider the noted features and some ways to implement them in more detail.
System manageability - the basic condition for energy-efficient heating. It is necessary to be able to control the temperature of the heating medium depending on the demand for heating.
In the simplest case, use thermostat with a coolant temperature sensor in the boiler flow or return line. The control is carried out by turning the boiler on and off according to the ratio of the set and current temperature.
A step towards improving the system is the installation of a programmable thermostat, which allows you to control the temperature of the coolant not only within the specified limits, but also by hours of the day and days of the week (Fig. 1).
Rice. one. Electronic thermostat with the ability to set heating modes for a week
The use of indoor thermostats, air temperature control and thermostatic radiator valves are effective if it is necessary to control the heating of individual rooms by switching on and off an individual heater or a dependent circuit, for example, heating one room.
To ensure the safety of the system in the boiler flow line, it is necessary thermostat set to the maximum allowable temperature.
Controllability of the heat generator - provision condition automatic regulation heat supply to the heating system, depending on the need for it.
The following methods of boiler power control are implemented: two-position (on-off), step, smooth (modulation) and step-progressive (combination of step and smooth control).
In general, power modulation makes it possible to increase the efficiency of the installation and minimize oscillatory processes in the operation of the system, which is important, for example, when controlling the temperature in individual circuits by means of electrically driven mixing valves.
Weather-compensated regulation consists in adapting the current parameters (power, coolant temperature) of the heating system or its individual circuits to weather conditions. As a rule, external (street) temperature and indoor air temperature are used as external influences. In some cases, humidity and atmospheric pressure are added to them.
The main advantages of the solution are increased comfort of heating, more efficient use of the plant's capacity and energy savings.
The control device is controller with weather compensation function. The regulation is carried out according to the specified dependence of the coolant temperature on the outside air temperature, called the heating curve (Fig. 2).
Rice. 2. Example of a family of heating curves:
on the abscissa axis is postponed outdoor temperature, along the ordinate axis - coolant temperature
The steepness of the slope of the curve and its shift along the ordinate axis are determined by the parameters of the heating system (the ratio of the power of the boiler and heating radiators, the thermal resistance of the walls of the building, the presence of additional external sources heat, etc.) and, as a rule, are found experimentally, through numerous observations and analysis of accumulated experience. The more accurately the heating curve is set, the more efficient the system will be and the more energy will be saved. In a number of weather-dependent controllers, in particular, E8 of the German company Kromschroder (Fig. 3), it is possible to automatically adjust the parameters of the heating curve, if the heating mode long time remains constant.
Rice. 3. Kromschroder E8 series controller
An important feature of some controllers with the function of weather compensation - the presence of a channel for proportional-integral (PI) control of the temperature of the coolant according to the temperature of the indoor air of the room. Thanks to electronic temperature sensors, this process can be carried out with high accuracy. IN controllers E8 temperature maintenance accuracy, taking into account the measurement error, is +/-0.3 C.
A number of operating and performance characteristics heating systems, including efficiency.
It is most convenient to set the gain control parameters in feedback contour (as implemented in the E8 model). So, if the room temperature deviates from the setpoint, the temperature of the heat carrier of the corresponding heating circuit is additionally corrected. As a result, for circuits serving very cold rooms, the coolant temperature will approach the maximum possible (boost mode). As the rooms warm up, the temperature of the coolant will decrease proportionally down to the value determined by the heating curve.
The control time constant is taken into account by setting the parameter of the space heating inertia, measured in hours.
The considered method of room temperature control is effective when sharing, for example, electric and furnace heating. With an increase in the room temperature due to the heat transfer of the furnace, the temperature of the heat carrier in the corresponding circuit decreases (up to its shutdown). This eliminates the need to manually manage the system.
Programmable room temperature control consists in changing the temperature setpoint of the premises heated by the circuit according to a given program. The implementation of this control method allows you to set the temperature of the premises in accordance with the needs for heating at the current time, which makes it possible to significantly reduce energy costs for heating.
The ability to set several programs, quickly change the heating schedule without resetting the temperature settings and time values can be used, for example, if, depending on the conditions of use of the system, the weather, the well-being of people, etc. different modes of space heating are required.
Most of the weather-dependent controllers on the market (manufacturers - Kromschroder, Honeywell, Fantini Cosmi, etc.) provide this.
Organization of separate independent temperature regimes for space heating - the next step in achieving comfort and saving energy spent on heating. The essence of the solution is that the heating of individual premises, their groups or buildings is carried out by its own subsystem (circuit). This is especially true if the serviced premises have different frequency of use, configuration, mass and heat capacity of the building envelope.
Separate heating is carried out due to the device of a multi-circuit system with one boiler or a cascade of heat generators. On fig. 4 shows an example of a simplified functional diagram of a heating system with an independent circuit and outdoor temperature control.
Rice. 4. Simplified functional diagram weather-dependent heating system with independent and dependent circuits: TG - heat generator; Hk - circulation pump collec-lecturer; Pk - heat consumers connected to the collector circuit; CM2, H2 - respectively, a three-way mixing valve with electric drive and a circulation pump of an independent circuit; P1 - heat consumers of the dependent circuit connected at points a, b; P2 - heat consumers of an independent circuit; Dk - coolant temperature sensor at the outlet of the heat generator; Du - outdoor temperature sensor; D1, Dp1 - coolant temperature sensors at the inlet of an independent circuit and room temperature, respectively; RK - separating valve with electric drive; K - control weather-dependent controller; red lines conditionally show the electrical connection of the system elements to the controller
The system works as follows. The circulation of the coolant through the collector and the dependent circuit is provided by the Hk pump; through an independent - pump H2. In the heat generator circuit (collector), the coolant flows from both circuits are added. According to temperature sensors on Du Street and in rooms Dp2 and Dp1, the manager controller K calculates the value of the temperature of the coolant in the collector circuit. As a rule, it corresponds to the maximum of those requested by each consumer, taking into account losses for the delivery of the coolant. The temperature of the heat carrier at the boiler outlet is continuously monitored by the Dk sensor, taking into account the readings of which the power of the heat generator (or cascade) is controlled.
The temperature of the heat carrier at the inlet of the independent circuit is also calculated taking into account the temperature outside and in the heated room and is controlled by the D2 sensor. According to the readings of the latter and the calculated temperature of the coolant at the inlet of the circuit, control is performed mixing valve CM2 by electric drive. With a large difference between the calculated and actual temperatures of the coolant at the inlet of an independent circuit, the direct branch of the valve is fully open and there is a parallel circulation of liquid through the collector and independent circuits, including the heat generator. As the coolant warms up in an independent circuit, the direct branch of the mixing valve begins to close together with the opening of the inlet connected to the return line, the cooled coolant from which is partially mixed into the circuit entering the inlet. Regardless of the degree of opening of the mixing valve, the circulation through the circuit associated with the latter remains constant. This solution has a significant advantage over the classical one- or two-pipe system heating with parallel circuits. When the direct branch is completely closed, the circulation in the heating circuits is carried out separately; heat consumption is determined only by consumers included in the dependent circuit Pk, and when the required design room temperatures are reached, the heat generator is turned off, the circulation pumps stop. In an independent circuit, the accumulated thermal energy is efficiently spent.
The executive elements of the considered heating system - circulation pumps, mixing, bypass, zone and other valves and drives to them - are widely represented on the domestic market. Examples of these devices are given in Fig. five.
Rice. Fig. 5. Examples of actuators for low power heating systems: a - a three-point control actuator for a rotary mixing valve (ESBE, Sweden); c - three-way rod separating valve (Heimeir, Germany); d - thermoelectric actuator of the stem valve (Honeywell, Germany); d - circulation pump (Grundfos, Denmark)
A controller such as E8.5064 (the "top" model of the E8 series mentioned above) is able to simultaneously control a two-stage boiler, two independent heating circuits with mixing valves and pumps, a DHW circuit, a solid fuel heat generator and solar collector. The temperature is measured and maintained in two separate rooms. When using expansion modules controlled via a digital bus, the number of independent heating circuits can be increased up to 16, and the number of boilers or their power levels - up to eight.
If necessary, the heating system must also take into account requirements for efficient energy consumption at joint work various sources (for example, electrical and solid fuel boilers, heat pump, solar plant) and consumers (radiators, "warm floor", DHW system) thermal energy.
In modern controllers heating, this is provided as a standard function or through the use of additional expansion modules.
Possibility remote control heating system allows you to achieve additional comfort in case the serviced premises are visited irregularly. The function in question is implemented if the heating system controller has the ability to change the operating mode via an external bus, which is also often used to configure and enter the operating parameters of the device via a personal computer. In controllers various manufacturers this is implemented differently. For example, in the EV87 regulator from Fantini Cosmi (Italy), the possibility of two-way data exchange is provided using the RS-232 interface and an open data exchange protocol supported by a GSM modem; control is performed by means of SMS-commands.
A number of modern controllers supports remote monitoring of the state of the heated object and the heating system. This is used to track emergency situations in the system operation, register temperatures outside the set values, accumulate statistics for fine-tuning control parameters, and perform scheduled maintenance.
Minimum thermal inertia of the system achieves technical and economic advantages.
The parameter under consideration affects the rate of transient processes (heating and cooling of the coolant) in the boiler and heaters. With high inertia in the heating system, such negative effects as overshoot, oscillatory nature and high duration of transient processes take place. In addition to additional energy costs resulting from inefficient control, these processes reduce the resource of heating equipment.
It is possible to reduce the inertia of the system by optimizing its design based on preliminary thermal and hydraulic calculations, reducing the volume of the coolant and metal consumption - by choosing the optimal sections of the hydraulic lines and installing heat-releasing devices with a minimum capacity.
Magazine "Aqua-Therm" №6(58)
Weather-dependent automation with a mixing three-way cock (valve) and a circulation pump. In this article, we continue the analysis of possible options for schematic solutions for the implementation of the device weather-compensated automation in individual heating point (ITP) or frame management of multi-storey residential buildings. This time we have a diagram of weather-dependent automation with a three-way mixing valve (valve) and a circulation pump.
In this scheme, regulation temperature in the heating system is due to changes (limitations) of coolant flow through a three-way valve and at the same time intake (admixture) of network water returned from the heating system of a residential building using network water or as it is also called circulation pump and supplying already diluted water again to the heating system of apartments. There are three main elements in this scheme - three-way valve, pump and controller - computer. It is the controller that constantly, at certain intervals, interrogates the temperature sensors of the coolant, outdoor air and air inside the apartments of a residential building (if any), processes the received information and, in accordance with the program entered into it (in this case temperature graph) generates a signal giving a command to the mechanism three-way valve for opening or closing.
This influence of the controller corrects the amount of opening or closing of the flow section of the control valve. If there is no indoor air sensor in this weather-compensated control system, then the weather regulation is carried out in accordance with the temperature schedule.
And, finally, the last type of automation for maintaining the temperature in apartments of residential buildings, depending on the temperature outside, is weather-dependent automation with a shut-off control valve and a circulation pump.
Let us analyze the principle of operation of this automation of maintaining the temperature in the apartment, or rather, in the entire multi-apartment residential building.
Here, the temperature in the heating system is controlled by changing bandwidth valve and, as in the previous scheme for mixing return (return) network water from a residential building using a circulation pump, now installed on the return pipeline heating system. In principle, where the network or circulation pump will be installed, it doesn’t really matter, it’s just that for a two-way valve such a scheme is still preferable because of its design features.
In the process of regulation, the controller also periodically interrogates the temperature sensors of the coolant in the heating system of the house, the room air sensors (if installed) and the outdoor air sensor. After processing the received information, the controller generates an output control signal to open or close the actuator of the two-way valve, while the value of opening or closing of the flow area of the control valve changes accordingly. With absence indoor air sensor The main priority of regulation is also maintaining the temperature in the apartments according to the temperature schedule.
There is only one drawback of control schemes with valves - the loss of electricity, for more information about the advantages and disadvantages of weather-dependent automatics, see the article.
The advantage of weather control schemes with valves
before the regulating elevator, the depth of regulation is usually called, although in our opinion such an advantage is controversial and can easily turn into a disadvantage if, for example, there is a thermal energy metering unit in the ITP, and its measurement limits are worse than the limits of the weather control automatics. After installing automatic weather control without coordination with the energy supply organization, such a UUTE can legally be recognized as non-commercial, which means that instead of saving you will again receive.
Weather-compensated control schemes with valves should be used in those ITP of residential buildings where it is technologically impossible to use elevators, and this:
- insufficient pressure at the inlet to the ITP, less than 0.07 MPa
- overestimated resistance internal system home heating, more than 5 m.
- installation on heating devices and risers of automatic control valves, for example, Danfoss
- usage independent system heating through heat exchangers.
I would also like to warn residents, especially weather-dependent automation schemes with mixing valves cannot be used without pump or with pump turned off . In the mode of operation with the pump turned off, the pumping of the coolant through the heaters sharply decreases, the difference in temperatures between the temperatures in the heaters different apartments sometimes it reaches 45 degrees, instead of twelve recommended for the economical mode of operation of weather-dependent automation. And most importantly, due to the lack of mixing in frosts, the temperature in the heating devices of the first apartments along the way can reach 115 degrees or more, which will inevitably lead to the failure of modern polypropylene pipes , as well as burns in case of accidental contact with heating appliances- this is at least. At the same time, the residents of the last apartments along the course of the coolant will sit in the cold.
This is such a savings, and according to the instruments everything will be OK. And most importantly, if he refuses check valve on the jumper between the direct and return pipelines, not only your house, but the entire area can be left without heat. The coolant will not go to the apartments, but will return back to the boiler room.
We dismantled possible options schematic solutions for the implementation of weather-dependent automation in the control frame of multi-storey residential buildings. In any case, the decision to choose one or another scheme of weather-dependent temperature control in the apartments of a residential building, and most importantly, the selection of equipment should be entrusted to specialists. You, as residents, should only say your word when choosing a design organization and the type of equipment - domestic or imported. it depends on that.
Everything purchased and installation and adjustment of automatic weather control in apartments of residential buildings on the next page.