Flushing gas central heating systems before further action
Taking the water out of a fully pumped central heating system makes many maintenance tasks easier. If you have a maintenance plan, such as British Gas Homecare, you may be spared this. If you need to maintain your central heating yourself read on. To exchange metal radiator valves or add an additional radiator as an example. Usually this function will be executed by your plumber but in some circumstances it can be performed by the experienced maintenance handyman.
Cleansing the radiators is the most frequent driver of this activity. Before any work is attempted you need to switch off the central heating pump and gas boiler. To enable the system to completely drain you will need to see to it that no water is getting into the heating system.
The heating system has a header tank in the attic which will ensure that any water shortfall is topped up. A common ball valve is used in the expansion water tank similar to that in a toilet. Rising water levels in the cistern mean that the valve is shut as the ball floats higher on the water surface. As the water level falls, say through Draining, the ball drops in the tank venting the valve and allowing more water to enter the gas heating system. This is what needs to be contained when Draining your metal radiator. Using a metal or wooden rod to stop the ball leaves are falling in the cistern will stop water moving into the system as the water is emptied.
When all these safeguards have been carried out, you should attach a hose pipe to the part of your heating radiator known as the outlet and run the end of the hose outdoors. Once you open the outlet valve the water will be able to current through the hosepipe to the outside flush. The hosepipe needs to be connected to the lowest point in your gas heating system which will be one of the ground floor radiators. Check now that no water is getting into the gas heating system and that the heating radiators are fully drained before you do any further work.
More air can enter the gas central heating system if you open the top floor radiator bleed valves and this will help things to conclude promptly. Work can begin when all the water has drained outside.