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To which temperature do the digits or scales on a thermostatic radiator valve correspond?

The numbers or scales on your thermostatic radiator valves do not correspond to a precise temperature but rather to a level of comfort. Through trial and error, you will find the setting that meets your needs!

Approximate conversion into degrees Celsius

It’s not possible to precisely convert the scales of your thermostatic radiator valve to degrees Celsius. This depends almost entirely on the layout of your room.

However, an approximate conversion can be made. For example, valve position * corresponds to a frost protection temperature and position 3 to approximately 20°C. Taking this as a guide, here is an approximate conversion table with the rooms and uses for which these settings are recommended.

Valve position Reference temperature Recommended setting for
* 6°C Frost protection
0-1 12°C Cellar, stairs
15°C Unoccupied room, laundry, recess
2 17°C Entrance hall, corridor
2-3 18°C Bedroom
3 19-20°C Kitchen
3-4 20-21°C Lounge, child’s bedroom
4 22°C Bathroom
5 max. Valve completely open

Why is the temperature not indicated on thermostatic radiator valves?

To understand this, you need a quick introduction to the workings of your thermostatic radiator valve: inside your valve is a thermostatic bulb which contains a liquid, a gel or a gas. This bulb expands or contracts depending on the ambient temperature. In doing so, it opens or closes a valve that lets the heated water into your radiator or prevents it from entering.

The reaction of the thermostatic bulb depends on the layout of your room. As such, the bulb is affected by the heat radiated by the radiator, the temperature of the water, the cold radiation of a wall or a window.

This is why it is impossible to precisely scale a thermostatic valve in degrees Celsius. Your thermostatic radiator valve therefore has marks such as: *, 1, 2, 3, 4, 5.

How do I properly set my thermostatic radiator valves?

Proceed as follows:

  1. play around a little at the beginning until you find the right temperature for you;
  2. stay away from it;
  3. resist the temptation to open the valve all the way when you go into the room in the morning and find it too cold;
  4. avoid setting the valve to minimum when it’s too hot;
  5. let the thermostatic bulb do its work naturally.

If you are only using a room thermostat as your heating equipment doesn't have thermostatic valves yet, it’s always a good idea to fit some. Find out why thermostatic valves combined with a room thermostat are the best way of getting the heating in your home just right! 

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