Toilet Flushing Problems



Perpetual flushing is a common condition in which water continues to enter the pan long after the toilet has been flushed. It happens because the cistern fills too quickly, stopping the siphon from drawing in the air which halts the flushing sequence. Instead, the siphon and ballvalve work in perfect unison, filling and emptying at the same rate.

The answer is to slow down the filling rate of the ballvalve, either by fitting a High Pressure (HP) seat in the valve itself, or by turning the stopcock on the supply pipe to lower the water pressure.



The weak link in a flush lever mechanism is the ‘S’ or ‘C’ hook connecting the lever arm, or push button, with the diaphragm lifting plate rod on the top of the siphon unit. New hooks are readily available from plumbers’ merchants in various lengths, and in an emergency you can improvise with a piece of coat-hanger wire.

Breakages elsewhere in the linkage are rare, but it should be obvious how the bits go together if you need to remove them. One point to check is that a lever arm hasn’t come loose from the cistern; if it has, retighten the backnut.

flushing problems 1

1. If the hook has disintegrated and the rod is ‘lost’ inside the siphon, reach underneath the siphon unit and push up the diaphragm to reveal it.

2. On most mechanisms, the hook can be ‘fiddled’ straight on to the rod and lever. Sometimes, however, you need to unscrew the lever arm first.



The most common siphon fault is a perished or torn diaphragm, but it’s also possible for the siphon housing itself to have cracked.

In both cases the first step is to turn off the water supply to the cistern, then flush it to empty the contents. Bale out any remaining water or soak it up with a sponge.

Next, you must unscrew and remove the siphon unit.

On a separate cistern, you can do this without removing the cistern itself.

On a close coupled cistern, the cistern must be disconnected and unscrewed from the wall, then lifted clear of the pan so that you gain access to the siphon securing nut (see How to Remove a Close Coupled Toilet Cistern).

On a siphonic toilet, it’s also worth checking the seal around the ‘puff pipe’ which creates the vacuum between the pan traps; if this is perished or out of position, the proper flushing action will be disrupted.

Check the siphon unit body carefully for signs of cracking before reassembling the parts.

1. On a separate cistern, unscrew the flush pipe coupling nut, then use a large wrench or slip joint pliers to undo the siphon nut above.

flushing problems 1 & 2

2. Lift up the siphon clear of the cistern and uncouple the hook on top of the lifting rod. You may need to remove the ball-valve float arm to clear it.

3. Slide off the lifting rod washers, noting their order, and put them to one side. Then slide the rod and plate out of the bottom of the siphon housing.

flushing problems 3 and 4

4. Remove the worn out diaphragm and draw round it to make a paper pattern. Buy a new diaphragm the same size, then reassemble in reverse order.


Trade Tip

Check the flush pipe

"If the diaphragm turns out to be broken, you can virtually guarantee that the rest of it is blocking the flush pipe or the flush ways in the pan. Blockages at other times are likely to be caused by foreign bodies — for example, parts of an old disinfectant dispenser.

If you can’t see all the way round the flush pipe, drop a small nut on the end of a piece of string down the pipe, then use the string to drag through a small piece of rag."

24. May 2011 by admin
Categories: Plumbing, Toilets | Tags: , | Comments Off on Toilet Flushing Problems


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