Active job

Under floor heating- want to be able to get it working

We need someone to come and set our underfloor heating. We have turned the plugs up to on in the meter box and turned the thermostat to 25. However it does not appear to be working. I have been told the power is used to heat up the floor from 9.30pm at night till 7 am in the morning, but nothing has happened. On the thermostat it says ETV