DIY How To

Draining a Hot Water Cylinder

A hot water cylinder is usually made of copper or stainless steel and located in a cupboard, this is usually known as an airing cupboard. The cylinder should be insulated to conserve heat and save energy, new cylinders are coated in an insulated foam, where as the older copper cylinders were left exposed and require a cylinder jacket fitting.

Drain hot water cylinder

Switch off any immersion heaters or boilers. Close the valve on the cold feed to the cylinder or drain the cold water storage tank and turn on the hot water taps.

There is normally a drain cock located at the bottom of the cylinder, connect a hose pipe and drain the water into a sink or drain that is lower than the cylinder. Open the drain cock by turning the square spindle using either a drain cock key or an adjustable spanner.

Drain cock

If the hot water cylinder is indirect there will be a coil of pipe inside the cylinder that is full of water which needs to be drained. This can be drained from the drain cock for the heating boiler. If the boiler is part of a central heating system then to save draining all the radiators, close all the valves on both sides of the radiators before opening the drain valve.

TipWhen closing a lockshield valve used for balancing the system, make a note of the number of turns so that each lockshield can be opened to the original position.

 
Syphoning the Hot Water Cylinder

If there is no drain cock for the hot water cylinder or if the drain cock is seized, the water can be drained by syphoning. Disconnect the vent pipe from the top of the cylinder, insert a hosepipe and syphon the water into a drain or sink.

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