How to switch underfloor heating on and off

it seems a silly question but there's a box on the wall with small glass cylinders inside little red sticks inside the glass. If I tighten or loosen the glass cylinder which way switches the heating on and off?

From that description it sounds more like your heating-cost-measurement thing - you don't want to be fiddling with that...!!

You should be looking for a thermostat/timer unit I would expect - will have a selector for temperature...something like this Underfloor heating thermostat

When the little red thing floats up its off (or at the lowest setting aprox 1 litre per hour)you can use the under floor heating at the moment to ‘cool ‘ your house ,let the water run through the system but turn your heating off ( or onto hot water only )

Hí Timezoner great you know what I'm talking about thanks for that do you know which way I should move the cylinder to switch it on/off

Some where in your house / flat are regulators sticking out of the wall small round knobs with numbers on them you adjust them (left) and the red thing drops down or up ( sorry must correct myself ,when the red thing is down it’s at the lowest setting ) I have the same system
I think

The glass tubes with the float in are just an indicator of the flow through each circuit. Don't attempt to turn them or they could break. Above (or below) them you'll find either some taps (older systems) or some servo motors that are connected to thermostats, typically in each room. If you have taps, normally clockwise would be off.

And just to add ,they regulate the flow but to turn your heating OFF you have to do this at the heating unit , normally has a sun , a moon and a tap symbol, = on ,half on or just hot water and so on

great thanks guy and timezoner there are no thermostats in the place at all and the house owners has complete control so if they feel like having our heat on during hot temperatures outside like today we can't control it they twisted these glass cylinders and either way I twist them the heating is on I think...cooler outside than inside...