Connection
How to connect the controller to the controlled device.
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Wired. Connecting with wires is the most common option. It is due to its main advantages — simplicity, reliability and low cost. On the other hand, the wiring itself can be quite troublesome and time-consuming.
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Wireless. Wireless connection — usually by radio channel. To do this, the kit usually provides an external transceiver connected to the controlled device. The main advantage of wireless models is obvious — they are much easier to install because no need to run extra wires. On the other hand, such a technique is much more expensive than wired, and communication has a limited range, which is further reduced if there are obstacles (such as thick walls) in the signal path.
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DIN rail. The phrase "on a DIN rail" traditionally refers to the method of installing the device (see "Mounting"); the connection is usually carried out by wire. However, this option is taken out separately for the reason that DIN devices are standardly mounted in a distribution cabinet — unlike conventional wired
thermostats, installed directly in the room. However, sometimes it is an advantage: the distribution cabinet can be locked with a key, restricting unauthorized access to the thermostat. Models with such a connection usually refer to professional equipment used in industrial
...facilities, warehouses, etc.Max. load
The maximum load in terms of current power that the thermostat can withstand. In other words, the maximum electrical power that it can pass through itself without failures and damage.
The choice for this parameter directly depends on the power consumed by the boiler or heater connected through the thermostat; load limitation is of particular importance when working with electric boilers, the energy consumption of which is measured in kilowatts. When connected directly, the power of the heater should not exceed the maximum load of the thermostat, otherwise the latter will simply fail. However, when using additional protective devices (contactors), many models allow connection to a more powerful load than originally allowed.
Air temp sensor
The presence
of an air temperature sensor in the design or delivery set of the controller — such a sensor can be either built into the device or external.
Air temperature is one of the key parameters that determine the climate in the room and the comfort of staying in it. Accordingly, the air temperature sensor allows the regulator to evaluate the general conditions in the room and control the heating operation, taking into account how the microclimate corresponds to the desired one. However, note that such sensors are not always applicable. For example, in kitchens and bathrooms, they may not work correctly (when hot water, a gas stove or a water heater is turned on, etc.), so in such conditions it is better to use floor temperature sensors (see below).
Sensor cable length
The length of the supplied cable in the wired thermostat sensor (see "Type"). The longer the cable, the further the temperature sensor can be installed from the device. At the same time, the principle “the more the better” is quite relevant: excess wire usually does not create any special problems, but if the length is insufficient, you will have to lengthen the cable, or even purchase another sensor.
Note that in modern models, the cable length usually does not exceed 4 m — this is usually enough when installing a thermostat in the same room but with the removal of the device outside the room, difficulties may already arise.
Minimum increment
The shortest duration a programmable thermostat cycle can have (see "Programmable cycles per day").
The lower this parameter (with the same number of cycles per day) — the wider the possibilities for programming the operation of the thermostat, in particular, for its specific setting (for example, you can provide a short period of preliminary "intensive heating" after working at low temperatures). On the other hand, due to a certain inertia in the operation of heating systems, it makes no sense to make an interval shorter than 10 minutes — the thermostat simply does not have time to work out the specified settings in less time. And in the most "long" models, this parameter is about 30 minutes.
Features
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Display. The presence of its own screen in the design of the regulator. Such a screen is usually a simple LCD matrix with segment digits. However, even on such a screen, very diverse data can be displayed (including temperature with an accuracy of fractions of a degree), and this function significantly expands the capabilities of the thermostat and makes it more convenient. Note that it makes sense to install the display primarily in electronic models (see "Device type"), for such thermostats it is almost mandatory (but in mechanical ones, on the contrary, it is almost never used).
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Protection of the pump from "souring". During non-working hours — for example, between heating seasons — deposits can form on the parts of the circulation pump of the heating system, which can make it difficult to rotate the impeller, reduce the efficiency of the pump, or even disable it altogether. This phenomenon is called "souring". To avoid it, automatic regulators may provide protection against acidification: periodically (once every few weeks) the pump is turned on for a short time, which prevents the formation of deposits (and removes those that have already formed).
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Holiday function. A special regime provided for in case of a long absence of people in the house (for example, during a vacation — hence the name). In holiday mode, you can set a certain temperature to
...be maintained for several days (for example, a week; the maximum duration depends on the thermostat model). At the same time, in some models, this function is combined with frost protection (see below) and allows you to set only the minimum temperature (usually 5 °C); in others, the holiday temperature can be programmed.
— Random mode. A mode that provides for the inclusion of various heating functions in a random order (but without causing critical loads on the heating system). The most popular use of this feature is to simulate that someone is at home; this can stop intruders planning a theft in the absence of the owners.
— Management via the Internet. Ability to control the controller via the Internet. The device itself is usually connected to the network via Wi-Fi, and the control features may be different. For example, in some models you need to use a proprietary application installed on a smartphone or tablet, in others it is enough to open a special page in any browser. However, anyway, this function allows you to control the heating system remotely, from anywhere in the world. This can be extremely convenient in unforeseen situations — for example, if during the absence of the owner on the street it gets warmer. In addition, additional features such as advanced timer programming may be available with Internet control.
— Frost protection. A function that prevents freezing of the coolant in heating systems. Freezing water expands, which can lead to mechanical damage and depressurization of the system. To avoid this, regulators with this function are able to "monitor" that the temperature of the coolant does not fall below 5 °C, and, if necessary, turn on the heating to maintain the temperature. This function is relevant primarily for cases when the disconnected heating system must be left unattended for a long time during the cold season.
— Protection from children (blocking). The ability to lock the control panel of the regulator so that a curious little child cannot knock down its settings. The lock, usually, is turned on and off in such a way that an adult, but not a child, can easily do it — for example, by simultaneously pressing certain keys.
— Heater operating hours counter. Built-in counter that tracks the total heating time. This feature makes it much easier to keep track of the operating mode and heat costs, eliminating the need for the user to keep records manually and allowing you to track working hours even when there is no one nearby.
— Sensor calibration t. Possibility to calibrate the temperature sensor of the thermostat. In fact, situations may arise when the readings of the temperature sensor for one reason or another differ from the actual temperature in the room — for example, the controller is installed near an electrical appliance that generates heat and knocks down the setting, and neither device can be moved. For such cases, calibration is provided — an amendment to the readings of the temperature sensor. For example, if the thermometer in the middle of the room reads 20°C and the regulator's sensor reads 22°C, you can correct the thermostat to -2°C and the temperature displayed on the regulator will correspond to the true temperature. Of course, the correction can also be taken "in the mind" without reconfiguring the device; however, most often it is easier to set the necessary parameters in advance and not get confused in the calculations.