What are these switches that are meant to move horizontally?

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Last time I had one was some years ago in Sweden, and it was pretty straightforward I guess. Now, in Germany, I am not sure if am taking the heater's full potential.

  • it's simply a thermostat. The small blue/red things just set the possible range! – Fattie Sep 30 '18 at 16:31
  • @Fattie the thermostat was not that ambiguous, but the stops were. Thanks! – gsamaras Oct 1 '18 at 19:06

These are standard radiator thermostat valves. They are usually marked

  • 0 — off (most thermostat valve heads don't have this setting)
  • ❄ — anti-frost (usually 6°C)
  • 1 — 12°C
  • ☽ — energy saving (usually 14°C)
  • 2 — 16°C
  • 3 — 20°C
  • 4 — 24°C
  • 5 — 28°C

Note these are target room temperatures. Regardless at which setting you put the thermostat, if the air around the knob is significantly cooler, the heater should get so hot you couldn't touch it.

If the heater doesn't warm up sufficiently, there may be air in the system. Ask the landlord to blow it off. Also, if this is a seldom used holiday flat, the boiler may still be set to energy saving/summer. Usually, there is a thermosensor on the outside of the building so the boiler can tell the four seasons automatically but who knows what the landlord has set up.

If you have additional heaters in the room, turn them off. This will make the towel heater get warmer. You could even open a window and the thermostat will make it fight against the cold.

EDIT: I was told the question was about the sliders marked with a blue and a red line respectively. These are mechanical stoppers. They can be fully removed and put into another notch of the valve head. They are meant to show what are reasonable settings for this valve, and are often glued into place in public spaces, so people couldn't play with the valve setting —at least not full range—.

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    Janka thank you for the detailed answer. However, the question was about the switches, colored in blue and red, that move horizontally (assuming vertical movement is for the thermostat vavle). If this is not clear, let me know. – gsamaras Sep 30 '18 at 14:50
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    Those red and blue switches are just mechanical stoppers for the turning. In your case, just a reminder what's reasonable. In public spaces, they are often glued into place so people cannot play with the heater setting. – Janka Sep 30 '18 at 14:54
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    ... and they help when changing the thermostat without looking. E.g. if you know that '3' is fine for you, you put the marker in this place and you can switch to this value with just a flick of your hand. – asdfex Sep 30 '18 at 15:39
  • In the US at least, removing air from a hot-water heating system is called "bleeding." It's not usually necessary to involve the landlord when bleeding a radiator. The term "blow off" denotes releasing steam from a steam boiler for any reason. – phoog Sep 30 '18 at 15:40
  • I found bleeding a radiator does nothing if there's no water refilled. You need access to the boiler to do that. – Janka Sep 30 '18 at 15:55

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