Cistern Syphon With Built-In Overflow

Yep.

Screwfix numbers:

With few inches of 22mm pipe

Keeps it permanently sealed with a white plastic cap.

Thx ..Can find the first one but not the second ....is that number correct .?

Stuart

It just goes over the top of the syphon, which is lower than the old syphon intended for use with a separate overflow.

It's always good to test an overflow can handle the full flow fill rate by holding the float fully submerged and checking the level doesn't rise to the point of coming out over the floor. You don't want to find out unexpectedly at some later date that the overflow isn't up to the job.

I used to think such a failure was unlikely, but having had a ball valve arm snap in half in the middle of the night a few months ago, I don't make any such assumptions anymore.

"Andrew Gabriel" wrote

I'd be suprised if many of the UKs toilet overflows can handle a fully open ball valve at reasonable mains pressure. I had a ball valve stick a few months back, and with a standard (1/2"?) plastic overflow outlet as the OP described, water finished up on the floor as well as in the drain. Looked like the overflow was sized for a leaking valve not a fully open one! Yes I did check to make sure the overflow was clear

Phil

In toilets is is best to have a siphon with an integral overflow. That will handle a 1/2" full bore.

In cold water tanks it is always better to have a 1" overflow pipe. 22mm will not be good enough. Or have two 22mm overflows.

They say you should throttle down the flow with an in-line isolator. Invariably these will be left on full.

On Wed, 28 Jun 2006 17:14:24 +0100 someone who may be "TheScullster" wrote this:-

One of the many reasons for not connecting toilets to mains water supplies if it can be avoided. The 22mm warning pipe can deal with low pressure supplies, but not (unrestricted) mains.

In this country warning pipes from cold water tanks should handle the full mains flow. None of those crappy English 22mm pipes. Full mains flow into my cold water tank looks very spectacular as it exits through the 40mm warning pipe and pours down three stories like a small waterfall onto the garden, but the water level does not rise in the tank to where there is a danger of the sides being overtopped. Peace of mind.

I guess thats why mine came with a 15mm feed and a restrictor..

I know that 'full taps' on the basin fills it up faster than the PLUGHOLE, let alone the basin overflow can cope with..toliet overflow is the least of my worries :-)

Then the flow is too great. Restrict the hot and cols taps.

In message , TheScullster writes

For various reasons I ended up fitting a 15mm overflow recently, it handles the full flow no problem, it has about a 1m drop and so sucks the water out of the cistern.