Boiler Control System Overview – Heat Control

Heating is one of the most important systems to ensure not only comfort, but also life in the room. In the construction industry, it is the design and installation of heating and hot water systems that accounts for a large part of the costs. The operation is not cheap either. However, the more complex the heating system, the more ways to reduce the operating costs without loss of comfort.Boiler control devices – a whole complex of different electronic components and parts. As an example, let’s take the basic components used to control the gas boilers.Let’s limit ourselves to those necessary for regulation: What matters to the user is not the systems themselves and their design, but the features they provide.

THE CENTRAL CONTROL MODULE

The name of the device differs from manufacturer to manufacturer, but the basic idea is the same: it makes the heating system work. The presence and number of other elements depends on the complexity of the system, but the central module must be present in any case – it is a kind of “brain. All other components – sensors, regulators, safety and control devices – are plugged into this control unit.

In most wall hung and floor standing boilers, the control module is installed directly in the body of the device. Often the module is also mounted with the corresponding cables busbars outside the boiler room: in a more convenient location for control – on the wall of the boiler room or even indoors.

What such a module should “be able to do? Depends on your needs. The minimum set – control of the burner, the safety systems, at least one heating circuit and the desired temperature. But only some low-powered wall hung gas boilers “for one or two rooms” have such a set of functions. For more complex cases you also need a more complex module. Without going into technical details, let’s list the main tasks and devices that, in theory, can be connected to the module.

The heating system can be low and high temperature or combined , single and multi-circuit, with different pumps for pumping liquids, a variety of control sensors we will not even dwell on these features: the number and type of elements depend on the design and characteristics of the boiler, burner and the system itself . It is possible to connect additional sensors and room controllers, which we will talk about a bit later. Often together with the heating system the DHW system is used, less often – additional heat generators: solar collectors, heat pumps, heaters. All of this also needs to be managed or at least coordinated.

It is clear that the level of sophistication of the control modules differs in all these cases. In a simple heating system unnecessary functions are likely never needed, in more complex systems there may be other devices other than those listed above. Even for quite simple small boilers, manufacturers sometimes offer at least two types of price modules, the first – for more or less typical tasks, the second – more complex and more expensive, of course . More complicated models are equipped with additional outputs for connecting various devices, especially additional control modules. In this way you can build a system of any complexity you require.

In cascade heating systems multi-boiler systems it is characterized by the use of control modules on each boiler. This is usually done in the following way: one module is designated as master, the others are slaves. Slave modules are usually started without a control panel: no manual control is required for each boiler, and one master module can also handle the joint operation of the system.

All elements of the boiler control systems communicate with each other via buses, although radio communication is also possible. Communication protocols of different manufacturers differ, so it is easier to count on the joint operation of all devices of the system, if the elements are ordered and installed from one manufacturer, by one service organization. It is not always possible for devices from different manufacturers to work together.

ROOM CONTROL MODULES

The comfort settings of a single module can be insufficient in a multiroom home. At least it makes sense to add a few more to the main living areas. For this, the room regulators are connected to the main module via a wired or radio link. In fact they are the same control modules but with fewer functions.

The easiest option – room thermostat. a simple “knob”. Its main disadvantage is connected with the inertia of the heating system: the process of temperature change takes up to several hours. Most of the room regulators are simple. Usually, they can be programmed to maintain the temperature automatically in accordance with the set program which also can be selected without going to the central unit and allow manual control.

TEMPERATURE SENSORS

The main purpose of making any heating system more complex is to provide maximum comfort with a minimum amount of thermal energy. This requires temperature sensors. In this case, it is realistic to program the system for automatic regulation.

There are three types of such regulation: “according to water”, “according to temperature” and “according to the weather”. The more control possibilities, the lower the heat consumption, the more comfort conditions can be achieved, but the system price goes up.

We do not consider temperature sensors for the heating and hot water circuits as they are more related to the boiler control system. It is also obvious that in order to supply water at the set temperature you will need actuators: pumps and capacity regulators on each circuit.

The easiest way to regulate – “by water” – is used in all urban apartments with central heating. The radiators are supplied with water of a given temperature, theoretically there is a regulator tap on each radiator, but in practice no one touches it. In fact, the central boiler house, of course, has its own regulation system, but there is virtually no feedback between it and the tenants, the water temperature is set centrally, and the user can not adjust it. Even if he starts calling the service organization and swearing, it is not certain that it will lead to any result in a reasonable amount of time. This type of control is very inertial.

If the system is supplemented with temperature sensors in the room, it is possible to reduce heating and keep it within the set limits by controlling the water temperature and capacity of each circuit. This is better, but only if the outside temperature does not change. The inertia of the system is here too, and the better the insulation, the later the sensor in the room will react to changes in the room temperature.

The most convenient and economical way is weather dependent regulation. Connected to the system is an outside temperature sensor. It is placed on an outside wall, preferably on the north or northwest side, in a place protected from the wind and direct sunlight. These sensors control the temperature of the boiler water in dependence on the outside temperature. Even better, if the outdoor sensor works together with indoor sensors.

The sensor itself is inexpensive, the control electronics is also not too complicated, and savings from the weather-dependent regulation reaches 20-30%.

SYSTEM PROGRAMMING

The complete system requires adjustment after installation, and there are two levels: manual and user. Here the analogy of a computer is the most relevant: specialists assemble, install and debug the programs, then the user is granted access rights but only to a few settings that are important to him.

The service technician should first check that all elements are working together. Usually, all the necessary software is already installed “filled in” in the modules. Some of the standard modules require additional configuration to meet the specific operating conditions, most are configured automatically without external intervention. Further settings include setting the permissible range of parameters for all elements e.g. if the system has a low temperature heating circuit, setting its temperature limit .

In order to provide both comfort and lower costs at the same time, different heating programs are used. It is estimated that a decrease in room temperature by one degree saves 5-7% of thermal energy. The main way to save here is to maintain an optimal temperature in each room if the system allows it according to a preset program and to be able to adjust it manually.

The need for heating varies at different times of the day. In the morning and evening, when everyone is at home, not only heat but also hot water is needed. At night it is better to reduce the temperature by a few degrees. Several standard heating programs can be “saved” in the memory – the user just has to choose the one that suits him. The standard heating programme includes one or more cycles of instant and sub-zero heating, sometimes with a different temperature during each period. It very often happens that no one is home during working hours on weekdays, and a different heating program is required on weekends. To save the hassle of reprogramming, many systems are able to “create” one or more “weekly” heating programs.

If the weather-dependent heating is used, it is also necessary to adjust the temperature curve, t. e. Program the required boiler water temperature this is determined by a sensor located at any point in the system, usually at the boiler inlet or outlet , depending on the outdoor temperature. Let us assume that the heating must be switched on at temperatures below 20 °C. This is the first point of the curve.

When the outside temperature decreases, more heating is required, but how much more heating is required depends on the conditions, in particular the heat loss of the building: the higher the heat loss, the more heating is required. Usually there are several such curves in the controller of the control module the desired one is selected according to the specific conditions. Once the curve is selected, the boiler water temperature is set at the lowest air temperature in the region. This ends the configuration.

The heating on/off time and the temperature curve setting can be programmed from either the user or service level. Some systems allow you to create your own heating programs, in addition to the standard.

Heating programs are convenient because they allow the system to work effectively in automatic mode. Several additional modes are available for even more convenience. Most of them can easily be started manually from the control unit.

The “winter/summer” mode is set either manually or automatically with weather-dependent control . If the system includes a DHW circuit, in the “summer” mode the energy is spent only on heating the sanitary water in the water heater tank, it is also possible to turn off the boiler completely. In case of prolonged absence from home it is reasonable to activate the “vacation” mode, which would maintain a pre-set low temperature, and the circuit would be set up in the “heating” mode

DHW will turn off. Of course, the frost protection program has priority over all other programs it does not turn the boiler off completely, but it uses less fuel.

Different manufacturers offer also some other preset programs, e.g. temporary switching off the heating for ventilation or a “party” mode, which can prolong the period of comfortable heating for a period of time. Other control functions available depend on the configuration of the system itself. If it has a water storage tank for DHW, you can set the modes of one-time heating when you need a large amount of hot water at odd times and thermal disinfection periodic heating of water to kill bacteria in it .

Switching all modes on and off is usually done from the central control knob. If the system has additional, room, regulators, some modes include and them, but it depends on the setting. In any case, there is nothing complicated about setting the desired mode on the user level.

REMOTE CONTROL SYSTEMS

In addition to wired communication and, occasionally, radio communication between the individual elements, many manufacturers are now developing devices capable of remote control and monitoring of heating systems and their management. Such systems are particularly suitable for intermittent residence, when the house is left unattended from time to time, and it is not important or unknown how long. This requires the inclusion of a suitable device in the system, most commonly a GSM module. In fact, it is the same as a cell phone or modem with a SIM-card.

There are several options, depending on the tasks in question. The first thing you need from the heating system in this case is the ability to switch the heating on and off when the owner periodically shows up at home. In principle, one channel with a pair of contacts is enough to realize this function when they are closed, a signal is sent to the control panel. Many controllers have such a channel, the required mode “switch on” or “switch off” is programmed in advance.

The rest is simple: you call or send an SMS to the mole number – the controller receives the signal and turns on or off the heating. The functionality of such a system is not too great in comparison with other methods, but it is sufficient enough for comfort and energy saving.

Different manufacturers may have other ways of controlling heat appliances via GSM-channel or fixed telephone network. Sometimes it is possible to regulate the temperature with such devices and the modem will send complete fault reports.

A lot more options are available if you use the Internet for remote control. The easiest way to connect – mobile, with a corresponding module with a SIM-card, alternatively – connection via fixed network. Theoretically it makes no difference, but in practice a fixed connection is more reliable: in case of overloading of the mobile network or its disconnection for various reasons remote control becomes impossible. Here you need to look at the location of the building: if it is located near special highways, special facilities, or just venues of large-scale celebrations, the mobile Internet can be turned off without any warning and no one to complain.

Of course, the control computer or an “advanced” cell phone will need to have the appropriate software. Possibilities of control via Internet are the same as with the usual control panel, but there are also the user and the service level. It is important that employees of service organizations can remotely reconfigure the equipment, monitor the system, and, in some cases, even remotely troubleshoot. Keep in mind, though, that continuous monitoring of the equipment by a third party organization is a paid service.

“SMART HOMES.”

The concept of a “smart house” implies centralized control and interaction of several systems at the same time. To create a comfortable room temperature is not enough, one also needs to take care of the ventilation or air conditioning system and the air humidity. Some elements which imply simultaneous operation of heating and other systems can be controlled by some of the existing controllers, for example, you can program the switching off of room heating when airing when a window opening sensor is connected.

Elements of the heating systems of different manufacturers communicate with each other using different protocols and different busbars – in general, “speak different languages”. To integrate “smart heating” into the “smart house”, you will most likely need an interface module gateway of the heating system controller connecting it with other systems not related to the heating equipment. The advantages of simultaneous control of all home systems, not only heating, are obvious, depending on the complexity of the system.

BACKUP POWER SUPPLY

In order to create a system that will be able to operate autonomously, it is necessary to provide for the possibility of switching off the electricity, without which the automation system will not work of course. Electronic devices and pumps of the heating system are not cheap and require high quality power. The best way to connect systems “to the socket” is through a stasis. Either batteries or mini power plants are used as a backup power source.

For battery back-up, the direct current usually 12V, but higher voltages are also available is converted to 220V by means of an electronic device, an inverter. The current quality in this case is excellent, the continuous operating time is quite long and can easily be increased by connecting additional batteries. The inverter is only connected to the most important consumers: the boiler controllers, controller and pumps, each of which consumes a maximum of 100-200 W, and not all the time.

The capacity of mini-electric power plants may be enough to power the entire house, but the issue of energy quality is more acute. Voltage dispersion produced by the station is within the permissible limits, but the “sine wave” may be far from ideal especially dangerous for pumps with “wet” rotor of heating and hot water systems . And not every power socket should be connected directly to the boiler. This can be explained in a nutshell: Almost all domestic appliances are equipped with a standard two-prong plug that can be plugged into the socket as desired.

But some types of technology including heating require observance of polarity. their “phase” and “minus” must be connected to the “phase” and “minus” of the power supply. In a fixed electrical system it is easy to find the appropriate outputs by connecting a voltmeter between the pins of the socket and the “ground”: on one pin you will find 220 V, on the other – “about zero”. Features of construction of many but not all generators are such that it is impossible to find the “minus”: there is voltage on both wires.

To ensure the safe operation of heating systems in conjunction with mini power plants, there are several methods. For example, it is possible to connect a 12 V accumulator to the station many stations have the corresponding output and to convert the direct current into alternating current using an inverter. Or use two inverters: one converts AC to DC, and the other converts DC back to AC. There are stations with inverter voltage generators, which have better current quality, but at the moment their output power rarely exceeds 2.0-2.5 kW, and you have to run such stations manually.

Another recommended component in the power system is an isolating transformer. Its task is to smooth out voltage spikes. It makes sense to use such a transformer for any connection scheme, including the inclusion in the power supply system of the generator. Power surges can be even at a very expensive station, especially at the moment when the fuel runs out and the engine starts “sneezing.

And finally, it is worth remembering that a complete reconnection of the power supply is a very expensive endeavor, especially if the automatic switching on of the reserve source is to be ensured during the failure of the main voltage. But these costs are justified: if the system freezes due to blackouts and lack of emergency power, its repair would be much more expensive.