By Patrick Gordon of Calafrica (

Patrick Gordon takes a look at the drain cock, with emphasis on how it must comply with SANS 10254.

Patrick Gordon

The next item in the water supply to the hot water cylinder (HWC) is the drain cock. All drain cocks used with a HWC must comply to SANS1808-53, but I am not going to discuss these criteria in this article. These drain cocks come in all different shapes and sizes and are designed by the HWC manufacturers to complement their specific product.

The purpose of the drain cock is to form an integral part of the HWC and to supply a suitable connection point to the reticulation system. Most of the manufacturers supply the drain cock with a compression fitting on the inlet of the valve. This is ideal as SANS 10254 requires a union type fitting on the inlet and outlet of the HWC for maintenance and replacement purposes. With the compression fitting being part of the fitting, you do not need to fit an extra compression fitting. Even though you may be using a non-copper pipe system, most of the municipalities have that as a requirement for a section of copper pipe to be used on each side of the HWC.

Supplied by Patrick Gordon

Supplied by Patrick Gordon

Not only does the drain cock make it easier to connect to the piping system, but it also does what the name suggests. You can drain the water from the HWC without having to disconnect it from the piping system. The design specification for a drain cock (SANS 1808-53) requires that a serrated tailpiece be part of the drain cock so that a hose can be attached when you need to empty the HWC. You would obviously exercise due caution when draining the HWC, so that the water that is being drained is not such that injuries can occur and that it will cause the hosepipe to dislodge while draining the HWC.

There are also other drain cocks available in the market that have extra connection points for use with solar systems. You should however make sure with the HWC manufacturer that the use of these fittings do not negate your warranty.

Look out for the next article. We will discuss the vacuum breakers.