Cascading connection. Features of cascade connection of gas boilers. Connection of two or more main heat generators

18.10.2019

Cascading boilers- this is an effective technique for increasing the unit power of the heating device, which has been used by heating specialists for many years. The reception concept is simple: we divide the total heat load between two or more independently controlled boilers and include in the cascade only those boilers that satisfy the demand for a given load at a certain time. Each boiler represents its own "step" of heat output in the total power of the system. The intelligent controller (microcontroller) constantly monitors the temperature of the coolant supply and determines which stages of the system should be switched on to maintain the set temperature.

Typically, examples are simple circuits connection of heating and hot water supply with one gas boiler selected from the conditions of its maximum load. In fact, practice has confirmed that during the heating season, approximately 80% of the time, the capacity of the boiler house is used by no more than 50%, and during the operating season, the load is, on average, 25-45%. Consequently, with such an uneven and often low load, one large-capacity boiler will waste energy resources unnecessarily and inefficiently compensate for heat costs. In this case effective solution is a cascade connection of boilers.

Example of cascade connection of three boilers

Usually, for examples, simple schemes for connecting heating and hot water supply with one gas boiler, selected from the conditions of its maximum load, are considered. In fact, practice has confirmed that during the heating season, approximately 80% of the time, the capacity of the boiler house is used by no more than 50%, and during the operating season, the load is, on average, 25-45%. Consequently, with such an uneven and often low load, one large-capacity boiler will waste energy resources unnecessarily and inefficiently compensate for heat costs. In this case, the cascade connection of boilers is an effective solution.

Boiler;
Hydraulic separator.

The cascade of boilers smoothly ensures the operation of the boiler house at the required capacity (in a wide range) regardless of the time of year due to the serial connection of several "small" boilers one after the other. With the help of cascade control with program control, the problem of determining the optimal ratio of the power of the boiler house and the heating system is solved. Thus, in the off-season and in warm winters, the cascade boiler house can operate for a long time at low temperatures coolant, which reduces the cost of heat radiation and periods of system standby. At the same time, the temperature conditions of the object improve, i.e. user comfort.

However, with an increase in the number of boilers in a cascade, heat losses through heat exchangers and bodies of idle boilers increase. Therefore, it is generally recommended to limit the number of boilers in a cascade to four.

The disadvantages of a cascade connection include the fact that the installation of several small-capacity boilers and the installation of additional components to control the cascade increases the cost of the heating system and requires more space than to install one powerful boiler, and it also complicates the connection of the cascade to the chimney.

As can be seen from the figure, in this scheme an additional device is included - a hydraulic separator. Let's figure out what kind of device it is and what it is used for?

hydraulic separator(arrow) is modern element heating systems. It is designed to separate the primary (heat generators) and secondary (consumers) circuits, creating a zone for reducing hydraulic resistance. Thus, the flow rate of the coolant in both circuits will completely depend only on the performance of the respective circulation pumps, the mutual influence of which is excluded in this case.

The hydraulic separator (arrow) ensures the hydraulic balance (and therefore the temperature balance) of the two circuits. When using a hydraulic separator, the coolant flow in the secondary circuit is ensured only when the corresponding circulation pump, which allows the system to respond to the thermal load at a given time. When the secondary circuit pump is turned off, there is no circulation in it and all the water circulating under the influence of the primary circuit pump is bypassed through the low loss header. Thus, when using a hydraulic switch in the primary circuit, it is possible to maintain a constant coolant flow, and in the secondary circuit, it can be effectively regulated in accordance with the heat load. In modern heating systems, this function is standard.

The ready-made hydraulic separator offered for sale is selected according to the catalog depending on the required boiler power (kW) and the maximum flow of the coolant in the system (l/h).

Cascade schemes of boiler rooms in one form or another have existed throughout virtually the entire history of the existence of this technology, regardless of the type of fuel and scope. Usually, the need to use such solutions was associated with limiting the power of an individual boiler unit or the range of operating modes allowed for it. However, with the development of technologies used both in the thermal-mechanical part of the design of boilers and in the field of automation, the use of cascade solutions is increasingly becoming not a forced measure, but the most technically and economically feasible choice.

In this article, we will look at the main advantages of using , various thermal and mechanical schemes and issues of automation of such boiler houses.

We will not focus on the advantages of a separate condensing boiler over a non-condensing (traditional) one. Somehow much greater efficiency and fault tolerance. However, we note the benefits of using such boilers in a cascade.

The main advantages of using boiler cascades

Most of the advantages listed below can be attributed not only to condensing boilers, but we will separately pay attention to what specifically distinguishes this type of equipment within the framework of the relevant topic.

Increasing the overall power modulation range

As noted above, main reason for the installation of several boilers in a cascade - an increase in the maximum power of the boiler house while limiting the performance of a single unit. From this point of view, any boilers are, one might say, in an equal position.

At the same time, one should not forget that modern systems heating systems are subject to increased requirements in terms of energy efficiency. And one of the main principles in ensuring this principle is to ensure that the current power of heat generators is equal to the needs of the system, no more and no less. Accordingly, the lower limit of the boiler capacity modulation also plays an important role. The use of a cascade helps to significantly reduce this boundary. It is also worth remembering that for mid-latitudes, most of the year, the need for heat is no more than 30-40% of the maximum.

When using identical heat generators in a cascade, the lower power limit is determined simply by dividing the minimum performance of an individual boiler by their number. And here it is easy to see in what a favorable light condensing boilers appear. The minimum modulation for the most modern wall-mounted boilers is approximately 15%. Accordingly, using, for example, four such boilers, we obtain a total stepless modulation range of 4-100%. Moreover, unlike traditional boilers, the efficiency of condensing boilers only increases with a decrease in modulation.

Ensuring a high level of fault tolerance of the boiler room

A fairly obvious advantage. The more boilers in a cascade are used, there is less drop in total power when an individual heat generator fails and is serviced.

Ease of installation and maintenance of equipment

Regardless of the total capacity of the boiler house, we often face space limitations both during design and installation.

Convenience for mounting and servicing organizations lies in the ease of delivery of a separate boiler to the place of direct installation at any stage. This is especially true for rooftop boilers, where, if it is necessary to replace the heat generator (albeit extremely unlikely), its lightness and compactness can play a critical role. In this context, also do not forget about the previous paragraph of this section.

Possibility of successive increase in boiler capacity

Increasingly used in recent times, the possibility of distributing investments to different stages of construction.

Cascade solutions allow you to sequentially add capacity to an existing system. Naturally, the hydraulic part should provide for the possibility of such expansion.

Hydraulic schemes

There are a lot of hydraulic schemes for piping cascade boiler houses. We will consider the main ones that are used when working with condensing boilers. General requirement Such schemes include the possibility of hydraulically independent operation of individual heat generators. This requirement primarily means the mandatory presence of a separate circulation pump for each boiler. In the most modern wall boilers industrial series, this pump is built-in. In order to ensure that the amount of circulation through a single boiler does not depend both on other boilers and on the operation of consumer systems, hydraulic separators are usually used, which are also known as “hydraulic arrows”. However, other ways of solving this problem are also possible.

Equivalent boilers with hydraulic separator

The most common option. Boilers are hydraulically equivalent, independence is ensured through the use of a hydraulic switch.

The number of boilers, of course, can be any economically feasible. Proper automation allows you to ensure a uniform development of the resource of boilers throughout the entire service life.

There is, however, a situation where such a scheme is not optimal when using condensing boilers. Namely, if the system's need for power for the preparation of hot water can be provided by a small part of the boilers from the entire cascade: one or two. For the most efficient operation of condensing boilers, a low-temperature consumer system operation schedule (with a return water temperature below the dew point) is desirable, while at the same time for rapid heating drinking water up to the required values, a high boiler water temperature is required. In order not to remove the entire cascade from the condensing mode for the duration of DHW preparation, the following scheme can be used.

Scheme with a hydraulic separator and a separate boiler for the needs of domestic hot water

In this case, it is possible to remove a separate boiler from the cascade to heat it up to a high temperature and prepare hot drinking water. The overall efficiency of the installation in this case increases. The average annual increase in efficiency is higher for systems with low temperature consumers.

The disadvantage of such a scheme, at the same time, is the large output of the resource by the boiler or boilers allocated for the purpose of providing hot water supply.

Schematic with main manifold for hydraulic independence

To illustrate that the hydraulic separator is not a mandatory component of the circuit, we present a variant of the circuit above.

In this case, to ensure the independence of the boilers, a closing section is used on the distribution manifold, which ensures constant circulation of the coolant through any heat generator. Such a scheme can be convenient in the case of using a rooftop boiler room and locating distribution systems for consumer circuits in the basement, as it saves space by abandoning the hydraulic switch.

But at the same time, the design of this solution requires paying special attention to the selection of boiler pumps, since they must also ensure the pressure loss in the main pipeline. For the same reason, this scheme is only used with floor-standing condensing boilers. In modern wall-mounted boilers, the pump is built-in and its performance range is precisely matched to ensure the efficient operation of a particular boiler.

Automation of cascade boiler houses

The role of automation tools cannot be overestimated in terms of the convenience of organizing cascade boiler houses, their reliability and efficiency.

It is automation that is responsible for “squeezing out” the maximum efficiency from boilers operating in a cascade, while ensuring the responsiveness of heat generators to signals from consumers.

In modern condensing boilers of industrial series, cascade logic is included in the basic automation and optimized for specific equipment.

The main functions of automation of a cascade boiler house:

Collection of requirements from consumers for heat generation and prioritization (DHW, heating, ventilation, etc.)

Determination of the optimal mode of operation of each individual boiler to ensure the required power.

Ensuring uniform development of the resource of boilers (with the rare exception discussed above).

Monitoring of accidents on boilers and signaling about them.

If we talk about the peculiarities of the work of automation with a cascade of condensing boilers, then it consists in the strategy of turning on and taking the boilers out of the current operation. There are three main strategies:

Turn on later, turn off earlier.
In this mode of operation, additional boilers are added to the operation as late as possible with an increase in heat demand, that is, the already switched on boilers operate at maximum power. With a decrease in power demand, the boilers are removed from the cascade as early as possible. This strategy ensures the smallest number of simultaneously operating boilers, their operation at maximum power and the shortest operating time of additional boilers.

Standard for non-condensing boilers. This is due to the fact that for non-condensing boilers there is a slight decrease in efficiency when operating at reduced modulation.

Turn on later, turn off later.
Turning additional boilers on as late as possible, but also turning off as late as possible. It is used when it is necessary to ensure the minimum number of operations for turning on the boiler burners.

Turn on earlier, turn off later.
Switching additional boilers on as early as possible with increasing heat demand and switching off as late as possible when it decreases.

It is this control strategy that is used with modern condensing boilers. At the same time, each individual boiler operates at a minimum modulation that ensures the need for heat. The number of operating boilers is maximum. As a result, we get maximum efficiency cascade installation with the most uniform depletion of the boiler resource.

A. Boyko

The use of several gas boilers for one heating system is a fairly popular solution among installation and design organizations. Consider practical matters regarding the installation and use of such cascade installations

The decision to use several gas (two or more) boilers for one heating system is justified with a heat load of 40 kW or more. This can be either a large heated area, or the presence of thermal loads in the form of pools, garages, baths, greenhouses, etc.

The use of several boilers for one heating system has a number of advantages compared to one boiler that has the same total capacity. Firstly, several small boilers of smaller size and weight are much easier and cheaper to deliver to the boiler room and install there instead of one large and heavy boiler. This moment becomes especially relevant when installing roof or semi-basement cascade boilers.

In addition, the reliability of the system is greatly improved. If one of the boilers is forced to stop, the system will continue to work, providing at least 50% of the power (if two boilers are installed).

Among other factors in favor of a cascade installation are ease of maintenance due to the smaller size of each boiler (maintenance of each boiler can be carried out without stopping the entire system); increase in the total resource of boilers (in autumn and spring, only part of the boilers can be operated by turning off the other part manually or using cascade automation).

In addition, if in the future it will be necessary to replace some part, then it is well known that parts for boilers of lower power are more accessible and cheaper due to the greater serial production.

Boiler control in cascade

Most often, to simplify the schemes when sharing boilers, no cascade automation is provided, and the required outlet temperature is set on each boiler. But, if desired, cascade control units can be used, which are connected to contacts intended for connecting individual room thermostats.

Connecting boilers in cascade using a cascade control unit is a complete solution and has a higher efficiency. This block ensures the alternating operation of all boilers and guarantees the same number of operating hours for each heat generator. The unit optimizes the functioning of the system and ensures that only the required number of heat generators are turned on, depending on the required power.

When working with modulating burners, the cascade control unit, in addition to the principle described above, seeks to ensure that the boilers operate in partial power mode (in modulation mode). The most effective is the use of a cascade control unit together with condensing boilers. In this case, the power supplied by the boilers is the most consistent with the power consumed. For example, when sharing three wall-mounted boilers of the LUNA Duo-tec MP series with a capacity of 100 kW (BAXI (Italy)), the power that is released smoothly changes from 30 to 300 kW, depending on the needs of the system. This means that the working regulation ratio of such a system will be 1:10. circuit diagram such a system is shown in Fig.

Rice. Scheme of a heating system with a cascade of Luna Duo-Tec MP boilers, one high-temperature circuit, two low-temperature circuits and a DHW boiler:
QAC 34 - sensor outdoor temperature; AVS 75 - external programmable expansion module; AGU 2.550 - internal expansion module; OCI 345 - interface board for connecting other regulators via LPB-bus; QAD 36 - clamp-on temperature sensor; QAZ 36 - water temperature sensor in the DHW tank; QAA 55 - sensor room temperature; QAA 75 - climate controller remote control; MV - mixing valve; RT - room mechanical thermostat

Condensation

Condensing boilers, due to their low fuel consumption, are currently the most economical installations that consume gas. As part of a cascade system, they represent a new alternative to industrial heating systems.

The use of condensing boilers with a capacity of 45 to 150 kW in cascades makes it possible to: provide more power in confined spaces; facilitate the installation of rooftop boilers due to the low specific weight of the equipment (per unit of power). In addition, condensing technology provides less vibration and noise compared to traditional forced draft boilers, and the presence of a built-in fan allows the use of small diameter chimneys (large and expensive chimneys can be dispensed with).

The environmental friendliness of condensing boilers, namely the very low content of CO and NO x in comparison with other boilers using traditional fuels, allows the use of such systems in large cities and nature protection areas. Among the shortcomings of condensing technology is the high cost (which, however, is offset by a short payback period due to an increase in gas tariffs), the need to organize the removal and neutralization of condensate.

Given the errors that are often encountered during the installation and maintenance of boilers, it is possible to determine the main recommendations regarding this.

In particular, it should be noted that when several boilers work together for one heating system with variable water flow (several separately controlled heating zones), it is recommended to use a hydraulic separator (“hydraulic arrow”).

In addition, when using the boiler for heating a small area (less than 100 m2), it is strongly recommended to use a room thermostat together with the boiler (to reduce the number of boiler on / off). It is also recommended to carry out a separate heating circuit power setting.

Otherwise, the recommendations for installing cascade boilers do not differ from the recommendations for installing other boilers. So, before connecting the heat generator to the heating system, it is necessary to thoroughly flush all the pipes of the boiler and the heating system to remove possible foreign particles. It is highly recommended to install a filter on the return pipe of the heating system and stopcocks on the supply and return pipes of the heating system.

Today, many consumers choose gas heat generators (boilers) as the main source of heat and water supply. There are several types of mounting gas equipment:

1 . One heat generator is installed in the heating system.

2 . Several heat generators are mounted in the heating system.

Consider the option of installing several heat generators in the system to compensate for heat losses. There are several types of control system with this design: parallel connection of each boiler, when each of the boilers works separately from each other, but for one system (heating, hot water supply, ventilation, etc.); and second, the cascading of boilers, when the equipment is installed and connected in one common system of thermal mechanical and electrical connection.

In this case, the cascade is combined by a single control system.

So what is a cascade? Cascade is one of the most effective ways increase in power limit or increase minimum power one device, but more on that later, but for now, for example, let's look at the operation of an individual heat point.

As practice shows, the equipment operates at the maximum heat load from three to five months a year with a rated heat load from 60 to 100%, while the remaining time the equipment operates at reduced power (from 40 to 60%). Let us take as a basis the inter-heating period from March to September and the area of \u200b\u200bthe heated room is 1000 m 2 or the heating of water in the hot water supply system. According to average calculations, 1 m 3 of combusted gas provides approximately 10 kW of boiler power. So if you have as heater one boiler with a capacity of 100 kW is used, then its minimum load will be 50 kW, which is equal to an average consumption of 5 m 3 of gas per hour. If you have a cascade of three boilers with a power of 36 kW each connected in your system, then, as practice shows, one of the heat generators with a minimum load of 10.6 kW will turn on, which equals an average gas flow of 1.6 m 3 per hour. As a result, when operating in the system of one gas heat generator with such a minimum load during the inter-heating period, its gas consumption will be almost three times higher compared to cascading boilers, and this is an increase in financial costs.

Typical installation schemes for gas burner equipment (cascade) are as follows.

The first is a simple cascade. This scheme includes gas equipment with single-stage or two-stage burners. When installing such a scheme, the equipment operates according to following principle: first, the first stage of the burner is switched on with a rated power of 70% (of the total power of the boiler), and if this power is not enough to compensate for heat losses, then the second stage is switched on with a power of 100%.

The second one is modulated. This installation scheme is more economical. It combines equipment with modulating burners. It is possible to smoothly change the volume of fuel supply and the ability to regulate the heat output in a fairly wide range. That is, the equipment turns on with a minimum thermal load of 40% and, if necessary, smoothly increases it to a power of 100% in 1% increments.

The main advantages of a cascade system with two or more gas boilers in front of conventional systems in which, as heating equipment only one gas boiler is used, these are.

First of all, the operation of gas equipment should be controlled by a cascade control unit or other automation. The multi-stage controller for a simple cascade system, using proportional-integral-derivative (PID) control, constantly measures the temperature of the heating medium supplied to the system, compares it with the calculated value and determines which burner should be turned on and which should be turned off.

One of the boilers of the cascade acts as a "master" and is switched on first of all, the rest, "slave", are connected as needed. Control automation allows you to transfer the role of the "leader" from one boiler to another, as well as to carry out the sequence of turning on the "slave". Also, automation carries out the sequence of turning on the equipment, which guarantees the same number of hours of operation of the gas burner. As a rule, the automation of the control system is supplied complete with an outdoor temperature sensor, which makes it possible to control the modulation of the gas burner device (power and flow temperature) depending on the temperature environment. For example, at an outdoor air temperature of 0 °C, the temperature of the heating medium in the supply line will be 50 °C. At an outdoor temperature of -10 °C, the coolant will be supplied to the supply line already at a temperature of 60 °C, etc. The lower the ambient temperature, the higher the coolant temperature. Automation will turn on the required number of boilers, depending on the required power.

Secondly, this is saving gas and, as a result, saving financial resources that can be directed to the reconstruction of your facility. The ability of boilers with modulating burners to reduce fuel consumption is often referred to as the burner operating control factor (the ratio of the maximum heat output of the boiler to the minimum). How can this be implemented? It's very simple, the system will do it for you.

Let's give an example - when the equipment is operating at a power of more than 70%, an increased gas consumption begins. You have two boilers with a capacity of 24 kW each. First, the first boiler is switched on with a rated load of 9.4 kW and gradually increases it to 100% power. If one boiler is not enough, then the second boiler is switched on, for example, at a capacity of 40%. In total, the total load of both boilers will be 32 kW. The second option - the first boiler is also turned on with a rated load of 9.4 kW and gradually increases to a power of 70%. If this power is not enough, then the second boiler is switched on at a power of 70%, and the total load will also be 32 kW. When operating gas equipment in the second variant, gas savings will be from 15 to 30%.

Thirdly, This is the ease of transportation and installation of equipment. Several wall-mounted boilers are much easier to install or mount than one powerful boiler. Sufficiently small dimensions and weight of wall-mounted boilers determine the advantage of installing them in a cascade when installing roof boilers, in basements or semi-basements. In particular, when installing such boilers, no additional costs are required for special equipment for lifting or transporting a powerful overall boiler.

Fourth, it's a reserve. If, for any reason, one of the boilers fails, for example, in the event of a heat generator failure, the entire system will continue to operate at reduced or medium power. If one boiler works in the system, and it “goes into error”, then the entire heating system will stop working, and in the cascade each boiler is autonomous, and in the event of an emergency, only the faulty unit will turn off.

Fifth, These are the conditions of placement. A cascade of wall-mounted heat generators is allowed to be mounted and operated in attached, built-in, free-standing, rooftop boilers, etc.

In practice, there are many examples when, during the reconstruction of an object, expansion and addition of additional heat consumers, it was necessary to modernize the boiler house itself (to change the existing gas equipment to a more powerful one), which led to large financial losses, and with the cascade control option, you can simply add to existing system with one or more boilers.

There are several options for placing gas equipment: mounting equipment on a wall, on specialized racks (mounts) in a row, or placing gas burner equipment “back to back”.

So, cascade boiler houses are used in almost all areas, but they are most in demand in systems autonomous heat supply one or more objects. When installing cascade control, potential customers and consumers do not need to build a heating main from centralized system heating, which, of course, has significant heat losses, especially with the DHW function.

The most profitable solution for cascade control is the installation of this equipment in private houses, restaurants, hotels, shops of various sizes, etc. If the customer knows how to count his money, wants to be sure of the safety, efficiency, reliability and quality of his equipment, then he will choose a boiler room consisting of a cascade of boilers.

Practice shows that 80% of the heating season, the boiler capacity is used only by 50%. This means that only 30% of the boiler capacity is consumed on average throughout the year. Such a weak load on often leads to low efficiency of its use. Therefore, the rational use of energy often requires an integrated approach. An excellent solution could be cascade system boilers. It provides the consumer with the amount of heat that is required at the moment, gradually connecting several small boilers one after the other.

What are the advantages of such a system?

First, high reliability. If one of the boilers fails, this does not mean that the entire system has stopped - the rest of the boilers will make up for the necessary load.
Secondly, increasing the total resource of boilers. In the warm season, you can use only a part of the boilers by turning off the rest manually or using the built-in automation.
Thirdly, economical energy consumption due to less loss of efficiency when operating at partial power.
Fourth, ease of installation. Several small boilers are easier to transport and install than one powerful large boiler.
Fifth, affordable repair and maintenance. It is much more problematic to get parts for high-power boilers due to smaller production volumes.

The advantages of such a system include the ability to vary the location of the boilers and the installation site itself.

The principle of cascade connection of boilers

The principle of cascade connection is to combine several boilers in order to increase the power of each piece of equipment.
To implement the reception of the cascade, it is necessary to divide the total heat load between several boilers and include in the cascade only those whose power corresponds to the required load in a certain period. In this case, one of the boilers acts as a "master" and starts working in the first place, and the rest of the boilers are switched on as needed.
The whole process is controlled by automatic control, which can transfer the role of the main boiler, as well as regulate the order and the need to connect secondary boilers to maintain the specified mode. In the cascade system, each boiler represents a certain “step” of heat output. The control system maintains the required temperature level by connecting or disconnecting individual steps. In the event of a malfunction of one boiler, automation distributes the load on the rest of the system. If there is no need for heat, automation turns off all boilers, restoring work on demand.
Stepped cascading system allows you to replenish loads with great efficiency heating system. However, it cannot be expected that the more boilers in the system, the more efficient their work. In proportion to the increase in the number of units, heat losses through the surfaces of idle boilers increase, so experts advise stopping at a cascade of a maximum of four boilers. For the smooth operation of the system, it is necessary to install a hydraulic separator between the heating and boiler circuits. It will ensure the reduction of hydraulic resistance and the hydraulic balance of the boiler and heating circuits.

What are boiler cascades?

It is customary to distinguish types of cascades according to the type of use of burners in them:

"Simple" the cascade includes boilers with single-stage or two-stage burners. Such a system increases the power levels of the boiler - for example, combining two boilers with single stage burner forms a more economical two-stage system.

Cascade "mixed" type combines boilers, one of which is equipped with a modulating burner. It is on this boiler that a control system is installed that regulates the temperature of the boiler water.

Part "modulating" The cascade includes boilers with modulating burners. In contrast to the "simple" and "mixed" cascades, this system is able to change the amount of fuel supply in a smooth mode and regulate the heat output in a wide range.

How to calculate and assemble a cascade

The calculation of the project of a cascade boiler house is based on the determination of the nominal thermal power of the heat source. This value represents thermal power required to replenish the heat consumed by the object and the power consumption of heat by other objects in the system.
The performance of the boiler house is not determined by the sum of all consumed capacities, but is calculated for each system individually.
Norm ČSN 06 0310 determines the calculations for the following objects:

Heating with intermittent water heating and ventilation:

Qtotal=0.7xQOtop+0.7QVent+QDHW(W, kW.)

Heating with continuous process heating and continuous ventilation:

Qtotal=QOtop+QTechn(W, kW.)

Heating and water heating in a flow way with the advantage of a DHW circuit:

Qtotal=maximum value of heat consumption for heating or DHW heating

Qtotal - total power of boilers

Qheat- heat loss of the object at the external design temperature

Qvent– heat demand of ventilation equipment

QDHW– heat demand for heating the DHW circuit

Qtech– heat demand for ventilation or process heating

The calculation of the boiler room requires a serious and professional approach, otherwise errors in the calculations can lead to inefficient and uneconomical operation of the system.

Assembly and installation of the system

The cascade boiler system consists of the following main parts:

Hydraulic cut-off;
Hydraulic connection of boilers;
Security group;
Heating of the DHW circuit;
Additional components.

The connection of the cascade system is carried out in several stages:

Installation of fixtures and boilers;
Installation of hydraulic collectors, gas line and drainage line;
Connection of safety group and hydraulic separator;
Smoke collector connection

First, two boilers are connected to a cascade, then the rest are connected. After combining the boilers, a security group is connected and the automation is configured.