People are only just realising what the numbers on radiator knobs mean That's because if you've got a TRV attached, you'll be able to limit or turn off the flow of hot water into the radiator.

Take a look at the radiators in your home, and they are likely to have a knob attached to the side with a number dial. It's known as a thermostatic radiator valve (TRV), and it can be used to ...