How to Replace a Ballvalve


New ballvalves aren’t expensive, so if you can’t get the parts to repair the old one (or it isn’t worth repairing) then buy a matching replacement. Replacing the entire valve is likely to cause problems, so aim to ‘graft’ the working part of the new one on to the tail of the old one so that you don’t have to disturb the supply pipe. Make sure you fit a new sealing washer where the two halves join.

If you have to replace the entire valve, or you are changing it for another type:

♦ Try to ensure the new valve has the same length tail as the old one; if not, you may have to modify the supply pipe (See Problem Solver below).

♦ On a toilet cistern, the length of the float arm may also be critical (though you can probably swap over the old one).

♦ Specify whether the valve is for high pressure or low pressure application (See Trade Tip – Pressure Points).

♦ If you live in a water area where dezincification is a problem, make sure the valve is plastic, or has a DR mark, indicating that it is dezincification-resistant.

Before you start, apply some penetrating oil to the connector nut and valve backnuts. Then, after turning off the water, open a tap lower down in the system to drain any water left in the supply pipe.

New valves are often supplied with self-sealing nylon backnuts which don’t need washers, but make sure the area around the nuts is clean and free of old jointing compound so that the seals are watertight. On a toilet, don’t over-tighten the nuts.

1. Taking care to support the supply pipe, undo the tap connector nut linking it to the valve tail. Pull the joint apart and gently ease the pipe away.

replacing a valve 1 & 2

2. Using slip-joint pliers and an adjustable wrench, loosen the backnuts holding the old valve in place. Unscrew the outer backnut and lift away the old valve.

3. Fit the new valve in place, not forgetting any sealing washers, and screw on the outer backnut. Hold the valve upright as you tighten it.

replacing a valve 3 & 4

4. Check that the supply pipe fits the valve tail, and if necessary adjust the backnuts. Fit a new fibre washer and retighten the connector nut.


Trade Tip

valves with standpipesValves with standpipes

"Some modern toilets require a bottom entry valve, which includes an integral standpipe. Valve operation is identical to the usual side-entry type.

If you’re fitting an identical replacement, you should be able to leave the standpipe in place and simply undo the valve at the union. Otherwise, be sure to quote the length of the standpipe when ordering a new valve."



Problem Solver

Bridging the gap

If you can’t get a new valve to match up to the existing supply pipe, don’t force the pipe — it may cause the joint to leak, or weaken others along the run.

persistent valve problemsNormally, adjusting the positions of the backnuts on the valve tail gives you enough room to manoeuvre. Failing this, you may find that a screw-on tap shank adaptor is long enough to bridge the gap. Otherwise, you have no option but to saw off the old tap connector and fit a new one, together with a new section of pipe.

Persistent valve problems

The Keraflo valve is a patented design which uses ceramic discs instead of washers to shut off the water. It is only made to fit toilet cisterns, but is claimed to be maintenance free and very reliable.

The valve comes in a basic unit to which you add a side entry connector or a separate standpipe for bottom entry. The fitting procedure is the same as for other ballvalves, but you may need an extending arm if the flushing handle restricts the float travel.

25. May 2011 by admin
Categories: Plumbing | Tags: | Comments Off on How to Replace a Ballvalve


Get every new post delivered to your Inbox

Join other followers: