We've moved into a small new build studio flat (5th floor of 7) two weeks ago and noticed that, despite the insulation quality, the flat was still chill. On inspection we realised that the bottom half of the 2 radiators were cold despite the heating system calling for heat constantly from 06:30 to 22:30 (thermostat set to 22 degrees) The highest we've managed to get the flat is 20.5 degrees, and that was with the oven on. When we managed to get the builders round to inspect the issue they said "the radiators should be cold on the bottom, because the flooring is cold" and "the radiator will heat up slowly because you've not set the thermostat high enough. Set it 35 to make it heat up quicker." Now, I'm no expert but I've used enough radiators to think that sounds like absolute nonsense. Can anyone confirm my suspicions, and shed light on what's actually going wrong?