Croydon and Portsmouth ball-valves

Filed Under: Do it yourself, Home repair, Plumbing    by: ITC

The oldest of the traditional types of ball- valves is the Croydon pattern. You can easily recognise one of these by the position of its piston, which operates vertically, and by the fact that it delivers water to the cistern in two insufferably noisy streams.

Due to their noisiness, Croydon valves are now by and large obsolete, and if you do come across one you will almost certainly want to replace it. The traditional type of valve that superseded the Croydon pattern was the Portsmouth valve (see illustration). You can distinguish it from the former type by the fact that its piston operates horizontally; and as it is still popular with plumbers despite the development of more sophisticated diaphragm type valves, it is a pattern that you may well find in your home.

When one of your ball-valves goes wrong the first thing you will notice is water dripping from an outside overflow pipe. If the valve is a Portsmouth pattern then it is likely to have developed one of three faults. First, it could have jammed partially open as a result of the build-up of scale or the presence of grit; or. secondly, it could need re-washering.

In either of these cases this will necessitate you turning off the water supply so that you can either clean the ball-valve or fit a new washer to it (see step-by-step photographs). Lastly, the valve could have been incorrectly adjusted to maintain the proper water level in the cistern .- which should be about 25mm (1 in) below the overflow pipe. Even modern Portsmouth valves are rarely provided with any specific means of adjusting the water level, so if you need to do so you will have to resort to bending the float arm.

Noise can be a problem with Portsmouth valves. It is caused either by the inrush of water through the valve nozzle, or by vibration created by the float bouncing on ripples on the surface of the water (`water hammer’).

As silencer tubes are now banned by water authorities, you will have to try.other methods to deal with this problem. Reducing the mains pressure by closing the rising main stop- valve slightly may help. and as vibration can be magnified by a loose rising main it is worth making sure that this pipe is properly secured with pipe clips. Another measure you could take would oe to improvise a stabiliser for the float using a submerged plastic flowerpot tied to the float arm with nylon cord. However, if all the above measures fail you will have to consider replacing the Portsmouth valve with one.

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