How to Service Ballvalves



Most ballvalves can be dismantled for cleaning and servicing, leaving the tail and supply pipe connection undisturbed. This is always preferable, especially if the supply pipe is lead, but it’s not worth trying to service a very old or badly scaled-up valve (see below).

New parts — washers, seats, floats — are widely and cheaply available from DIY stores or plumber’s merchants. But as with taps, you may need to take the old parts with you.

The first step is to turn off the water supplying the valve at the nearest stopcock. Check the water has stopped flowing by pressing down on the float arm.

When unscrewing the valve body, take care not to let it turn or you’ll break the seal on the tank/toilet cistern and strain the supply pipe connection.

Tools and materials: Adjustable spanner, wrench, self-locking wrench, small screwdriver, pliers, PTFE tape.


Servicing a Piston Valve

After removing the working part of the valve (see step below), dismantle it following the diagram.

♦ Remove the split pin and unscrew the end cap, then wiggle out the float arm and slide out the piston.

♦ Hold the piston with a screwdriver and unscrew the end. (Newer pistons are in one piece.)

♦ Dig out the old washer; replace it with an identical size and type.

♦ Replace the seating with one of the same size and pressure rating if it looks worn or is cracked.

♦ Scour off any scale, then give the piston and body a thorough clean with metal polish.

♦ Before re-assembling, check the condition of the union washer and replace if necessary.


servicing a piston valve


Trade Tip

Pressure points

“Most newer ballvalves have replaceable seats with the outlet holes sized according to the pressure of the water passing through them.

Low pressure seats are for toilet cisterns fed from storage tanks. High pressure seats are for storage tanks and toilet cisterns fed direct from the mains.

You can also get full-way seats for toilet cisterns that fill painfully slowly because the storage tank is too low-down in the house to provide the normal amount of pressure.

Always specify what pressure rating you want when buying new parts or a new valve. Armed with this information, you can also cure a valve that fills too slowly or quickly (and thus noisily) simply by changing the seat accordingly.”

Trade Tip

in an emergencyIn an emergency

“At the first sign of a drip from the overflow, bend down the float arm (or on a plastic valve, adjust the arm) so that more pressure is applied on the washer. As with a leaking tap, you could also try turning the washer round the other way.”



♦ On most diaphragm valves, the diaphragm is immediately behind the retaining nut. But on one type the nut is in the middle of the valve (inset), and you have to slide out a cartridge to expose the diaphragm. In this case, take care not to damage the sealing washer behind the seat.

servincing a diaphragm valve

♦ Dig out the diaphragm with a flat-bladed screwdriver and check that the seat is in good condition.

♦ The new diaphragm only fits one way, so check the old one to see which side was marked by the seat.

♦ Reassemble the valve and screw the retaining nut back on by hand Turn on water and test immediately.



A constant drip from the front of the valve during filling is normal, but if you suspect the diaphragm needs replacing:

♦ Unscrew the front of the valve body.

♦ Dig out the diaphragm and clean in soapy water. It could be that this cures the problem; if not, replace the diaphragm.

♦ Replace the diaphragm with the white spike pointing towards the valve. Position the bush on the outer edge of the diaphragm on the steel pin fixed to the valve body.

♦ Replace the front cover, checking that the float arm engages on the plastic pins.

♦ Adjust the water level by altering the position of the float on the arm.

torbeck valve

Instead of different size seatings the Torbeck valve comes with a choice of flow restrictors for high and medium pressure. But if the valve takes more than 20 seconds to fill, it’s more likely that the filter is blocked so check this first. (Early models may not have a filter.)

25. May 2011 by admin
Categories: Plumbing | Tags: | Comments Off on How to Service Ballvalves


Get every new post delivered to your Inbox

Join other followers: