Emptying gas heating systems before additional work is carried out on the system is sometimes an absolute necessity. It is impossible to take a radiator off a wall or replace a heating valve when the central heating system is still full of water.

Flushing a fully pumped gas heating system makes it easier to work on the system. To entirely flush the system of gunk and contaminants could be one such example. This is often executed by the engineer during repair or extension work although some experienced homeowners have been known to empty their own gas central heating systems.

Cleaning the metal radiators is the most popular driver of this action. Before you do anything to the actual heating radiator you should turn off the heating boiler and any gas or electric that supplies the central heating boiler. To enable the system to entirely clean you will need to check that no water is entering the central heating system. We cannot stress this enough, if you have any doubts stop, pick up the phone and get an expert in. If the boiler is still operating and certainly if the pump is still running the moment you open a valve or loosen a radiator your house will be full of water and your boiler will start to overheat – now that would be foolish wouldn’t it.

Your gas heating system is topped up with water via the expansion or header cystern. A ball valve mechanism, as used in toilets, is used in the expansion tank to regulate the rate of flow of water. This ball valve is a ball attached to an arm that, when lifted closes the valve, which means when the cylinder is full no more water can get in as the valve is blocked. However when some water is drawn off the tank, the ball drops, the valve opens and more water gets into the cystern. To fully clear the gas heating system this top up process will need to be stopped. One of the best ways to end this is by placing a piece of wood across the cystern and binding the value arm to it, which will close this valve.

When you are confident that you are prevented any further water entering the heating system you should attach a hose pipe to the outlet valve at the bottom of a heating radiator taking care to ensure the end of the hose pipe is in a flush outdoors your property. The central heating system can now empty by water flowing out of the heating radiator, through the outlet valve, and into the external drain. As there will be water in the bottom floor metal radiators you will need to attach the hose to one of these to guarantee that the whole heating system drains. Before you begin any other work on this central heating system you must now check that all the water has emptied out and no other the water is entering into the radiators.

By opening the bleed valves in the metal radiators on the top story you will help air to enter the gas heating system and quicken up the Draining process. When completed work can now begin on the system.

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