Setting the temperature on the carrier thermostat

Setting the radiator thermostat: this is how it works!

When it's cold outside, our hand automatically moves to the radiator thermostat. The rotary knob on the side of the heater ensures that it will soon be comfortably warm again, at least in your own four walls. However, if you use the device incorrectly, you may literally "burn up" your money. That is why we would like to show you in this guide how to set the radiator thermostat correctly - so that it gets warm and you save your wallet!

Table of Contents

  1. What actually is a radiator thermostat?
  2. Setting the radiator thermostat: which number corresponds to which temperature?
  3. How exactly does the radiator thermostat work?
  4. What to look for when setting the radiator thermostat
  5. Radiator thermostat broken?

What actually is a radiator thermostat?

Mechanical radiator thermostats

First of all: There are digital and mechanical radiator thermostats, also known as thermostatic heads. A mechanical radiator thermostat is the white, fluted knob on the side of your heater. It essentially consists of three parts: The visible white housing; a temperature sensor that fills the inside of the housing and a transmission pin that extends from the thermostat to the valve of the heater.

The rotary knob works like this: If you turn it closed, the pin presses harder on the heating valve behind it, which narrows the valve opening. The result: less water can flow through the heater and the room does not get warmer.

No matter how high you set your heating, your radiator will not always simply keep heating up anyway: the integrated temperature sensor is there for that. It measures the temperature of the room and compares it with the current heating output of the heating system. If there is a discrepancy, it increases or decreases the output accordingly.

Digital radiator thermostats

Digital radiator thermostats are becoming more and more popular. They enable the desired room air temperature to be adjusted even more precisely, thereby ensuring particularly energy-efficient and cost-saving heating. They can also be operated remotely using a smartphone or tablet. The advantage: You can have your heater preheated on the way home so that the temperature is perfect when you get home.

Intelligent individual room control

Some smart home providers offer intelligent heating controls that communicate directly with the heat generator when the radiators in the apartment are turned down. Then the boiler heats less and thus saves energy.

Setting the radiator thermostat: which number corresponds to which temperature?

The edge of the radiator thermostat has numbers from one to five, with three lines between each number. What very few people know: The numbers stand for relatively precise temperature information.

  • Star symbol: approx. 5 ° C, frost protection

  • Level 1: approx. 12 ° C

  • Level 2: around 16 ° C

  • Level 3: approx. 20 ° C

  • Level 4: around 24 ° C

  • Level 5: approx. 28 ° C

The lines mentioned between these levels stand for the intermediate temperatures: Each line corresponds to one degree.

How exactly does the radiator thermostat work?

Even if you set your radiator thermostat to 20 ° C, the actual temperature may differ slightly. This is usually related to the position of the radiator and any resulting accumulated heat. If the radiator is covered by a curtain or a sofa, for example, the heat builds up behind it. The temperature sensor of the thermostat reports to the heating system that it should shut down, although the regular room air temperature is still too low. Heat can also easily build up between the radiator and the window sill.

This problem is the reason why no temperature information is given on the edges of the thermostats. As a consequence, this means: Depending on the room and the position of the radiator in it, different settings may be necessary, although the same temperature is always desired.

Incidentally, the problem can be circumvented using so-called remote sensors. Thanks to an extended sensor, they measure the temperature in the center of the room and thus avoid the local build-up of heat. Many digital radiator thermostats already have this function.

What to look for when setting the radiator thermostat

Higher is not the same as faster

Perhaps the most popular mistake when setting the radiator thermostat: turn the controller up to the maximum so that it warms up faster. Suppose you want to heat your home to around 20 ° C, which corresponds to level 3 on the thermostat. Because you are particularly cold, turn the button all the way up, following the motto "a lot helps a lot". But that's not true in this case. You can reach your target temperature of around 20 ° C just as quickly if you just set the button to level 3. If you set it to level 5 instead, the radiator will continue to heat up to around 28 ° C after the actually desired target temperature has been reached. The result: it gets too hot, you feel uncomfortable and waste heating energy.

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Should you even downgrade?

Due to the temperature sensor built into the radiator thermostat, this is an absolutely legitimate question. Because once the desired target temperature has been reached, for example 20 ° C, the heating throttles the heat generation and only re-heats if necessary. This means that you do not waste any energy if you leave the radiator thermostat permanently set to the desired target temperature.

But there are exceptions or restrictions. If the room temperature is high, the outside temperature is very low and the thermal insulation is poor, an above-average amount of heat escapes to the outside due to the gradient. It can make sense to turn this down in order to save energy. With good insulation, on the other hand, it is worth keeping the thermostat constant.

A second point: most people prefer a lower room temperature at night than during the day - and a cooler room climate actually benefits the quality of our sleep. If night setback is set on the central controller of your boiler, you do not have to do anything else: Your heating system will reduce the temperature at night regardless of the setting of the radiator thermostat. If this is not the case, you should manually lower the temperature on the radiator before going to bed.

How do you heat properly during the day when you are absent?

If no one is in the heated rooms, for example because you work during the day, it also makes sense to turn the heating down. Warning: You should not switch off the heating completely. If you do, you have to use more energy in the evening when you return than if you had continued to heat at a slightly lower level during the day.

And what about a longer absence?

"Well," one or the other might say, "the heating really has to be turned all the way down!" Which is why many heating owners turn down the frost protection symbol during their vacation - at least nobody wants to risk frozen or burst pipes.

Still, that's not ideal. First: The frost protection setting prevents the rooms from cooling down too much - but the pipes in unheated rooms can still freeze. To prevent this, you should leave at least one radiator at the end of the respective heating section at at least 18 ° C (position 2-3). And please do not turn off the heating pump or even the entire heating.

Second: If you set your heating to the frost protection symbol, this only guarantees a temperature of 5 ° C - this is so low that mold can develop in the rooms if you are absent for a longer period and under appropriate external conditions. To prevent this, the Federal Environment Agency recommends a basic temperature of 15 ° C if you are absent for a longer period of time.

Different temperatures for different rooms

There is one more important point to note in order to set the radiator thermostat correctly and to save money in the long term: Not every room in the house or apartment needs the same temperature. The following list shows you the ideal temperatures:

  • Living room: 20 to 22 ° C

  • Study and children's room: 20 to 22 ° C

  • Kitchen: 18 to 20 ° C

  • Bath: 24 to 26 ° C

  • Bedroom: 16 to 18 ° C

Radiator thermostat broken?

Radiator thermostats are wearing parts: after all, they are turned on and off hundreds of times a year. If you find that your radiator stays warm permanently or does not get warm at all, you may have to replace your radiator thermostat. Your heating contractor's experts can help you here. You can quickly find competent heating installers in your area via our platform.

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