Turning down the heating while he's away is commendable. That lowers consumption. But sometimes the apartment cools down a bit too much. Is it useful to turn up the thermostat to the max to quickly have it cozy and warm again at home?
Quite a few assume that the room will warm up faster when the thermostat is on the highest level. Accordingly, they always turn the knob all the way when they come into a cold home. But that's not true, as the non-profit consulting company co2online explains. Because a heating thermostat is not a faucet. If it is turned up full, you do not heat faster, just longer - until the higher temperature is reached. This results in rising heating costs.
Determining the desired room temperature is not always easy in practice - especially when the thermostats do not have a temperature display. Level 1 basically corresponds to a temperature of 12 degrees. The distance between a step is about 4 degrees, the small dashes in between each mark one degree. Level 5 corresponds to about 28 degrees.
If you want it to be more transparent, you should exchange your old radiator thermostats for new ones with a temperature display. You can buy them from ten euros each. Depending on the general conditions, the new thermostats can save up to ten percent on heating costs per year.