This is the MISTAKE we all make when bleeding radiators 4 things you absolutely must do before turning them on

Bleeding radiators looks easy. Turn the valve, hiss, a drop of water – done. But this is where the most common mistake occurs, which causes the heating to heat unevenly, hum or unnecessarily increase energy consumption. If you want your radiators to work quietly and fully, read on.

The most common mistake

Most people bleed radiators with the heating on or without any preparation. This gets more air into the system, the pressure drops and the problem returns – sometimes even worse.

4 things you must do BEFORE turning on the heating

Switch off the heating and let the system cool down

Never bleed radiators while the heating is running. Hot water is under pressure and air is moving in the system.

Correct: turn off the boiler (or central heating) and wait at least 30-60 minutes for the radiators to cool down.

Check the pressure in the heating system

The pressure always drops after bleeding. If the pressure is already low, you risk the radiators not heating at all when you turn them on.

Ideal pressure: usually 1-1.5 bar (depending on the system).

If it is lower, let the water in first.

Have a cloth or container ready

It sounds trivial, but many people underestimate this. Water can spray out under pressure and stain the wall or floor.

Have a cloth, bowl or small cup handy.

Open the valve slowly.

Start with the lowest radiator

This is the key to success. Air rises – so:

First bleed the radiators on the ground floor

Then continue upwards

Lastly the radiators on the top floor

If you start at the top, the air can only move elsewhere.

What to do after bleeding

Check the pressure again

If necessary, add water

Only then turn on the heating
After heating, check that the radiators heat evenly and without noise
Extra tip

If you have to bleed your radiators frequently, this may indicate a leak, a faulty expansion valve or an old system. In this case, it pays to have a professional check – you will save energy and nerves.

Do you make any of these mistakes, or do you have your own trick that has worked for years?