How to flush a heating system
Flushing out your heating system is often advisable before you fit a new boiler or make any changes to your heating system. It may well be that there's sludge and residue in the system which hasn't manifested itself as a problem in any way previously. Flushing out your heating system is also a good idea if your heating system is banging, clunking and has decreased efficiency.
Level of difficulty
Level 2: Intermediate
What you need
- Old rag
- Corrosion inhibitor
The steps to follow
- Turn off the mains water supply, the boiler, and the water heating pump.
- Don’t let water fill up in the water storage cistern of the central heating system. To do so, you'll need to stop the ball valve from floating on the water surface and reaching a certain height. Tape or tie the ball valve to the side of the water storage cistern.
- Next, drain the water out of the radiator.
- Attach one end of the hose to a tap and insert the other end into the radiator opening.
- Unscrew the radiator valve on the other end to discharge the waste water.
- The waste water will initially be murky, but it will eventually clear out.
- Repeat the above step for the rest of the radiators until all radiators have been flushed.
- Flush through the boiler and add corrosion inhibitor to the water system.
- Bleed the radiator before you turn the heating system on.
- Turn the mains water supply back on when you’ve finished.