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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> No overflow on toilet cistern? https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1419293139 Message started by jazzyman on Dec 23^rd, 2014, 12:05am

Title: No overflow on toilet cistern?
Post by jazzyman on Dec 23^rd, 2014, 12:05am

I had a replacement toilet cistern fitted last year (housing association) property. I remember the person that fitted the cistern saying that there were no overflows on new toilets.
I had to remove the cistern lid the other day and I cannot find any indication of any type of internal overflow, I even overfilled the the cistern up with water just below the blanked off overflow outlet hole, there was no sign of any water overflowing down the pan etc..

How do you check if the cistern is fitted with an internal overflow?

Title: Re: No overflow on toilet cistern?
Post by CWatters on Dec 26^th, 2014, 9:38pm

It depends on the type of flush valve. With many modern valves the water goes down through the centre of the flush valve which is a hollow tube. For example..

http://cdn.toolstation.com/images/141020-UK/250/86200.jpg
or

Otherwise if it's a syphon type the water rises until it "goes over the syphon" pipe as it does when flushed..
https://www.youtube.com/watch?v=B4syY1onCp4

If that doesn't help can you post a picture or a link to one that looks similar? Try google images.

The internal overflow should work before water overflows the cistern so perhaps test it by filling the cistern slowly with a jug. EDIT: Oops I see you've tried that.

Title: Re: No overflow on toilet cistern?
Post by Natedog on Dec 28^th, 2014, 4:09pm

a pic of the inside of the cistern would help

Title: Re: No overflow on toilet cistern?
Post by jazzyman on Jan 3^rd, 2015, 5:51pm

Toilet valve is a Dudley Cascade FTS7B

Title: Re: No overflow on toilet cistern?
Post by TIMBA-WOLF on Jan 4^th, 2015, 4:10pm

The S7 is not a Dual, or internal over flow syphon, according to Dudley's web site:

Just a basic "BOG" standard syphon...

Title: Re: No overflow on toilet cistern?
Post by CWatters on Jan 4^th, 2015, 6:36pm

If the water level rises too much doesn't it just flow over the syphon? or is the syphon too high?

See bottom of page 30...
http://www.plumbcenter.co.uk/wcsstore7.00.00.168/ExtendedSitesCatalogAssetStore/images/products/AssetPush/DTP_AssetPushHighRes/std.lang.all/hu/re/TDudley_Turbo88_Brochure.pdf

and top of page 6..
http://www.masefield-beta.co.uk/assets/files/pdfs/ME-Catalogue-web.pdf

Quote:

Any syphon is capable of acting as an 'Overflow', as long as the cistern wall is higher than the total height of the installed syphon.(Any holes in cistern walls should be higher than the syphon or should be sealed with a suitable stopper)

Title: Re: No overflow on toilet cistern?
Post by jazzyman on Jan 8^th, 2015, 10:55pm

CWatters wrote on Jan 4^th, 2015, 6:36pm:

If the water level rises too much doesn't it just flow over the syphon? or is the syphon too high?

Looks like the syphon is to high. I filled the tank more or less to the very top and then the overflow worked, draining back to the pan, the problem then water was leaking from the overflow blanking plate. I measured the hight of the syphon valve and it's approximately 9", so I guess this is to high. Another picture below.

Title: Re: No overflow on toilet cistern?
Post by CWatters on Jan 9^th, 2015, 12:16pm

Best replace the flush valve. There are several types of slush valve that have an adjustable overflow level. Just check they go low enough for your max water level. One Example..

http://www.toolstation.com/shop/p51299

or perhaps seal the over flow blanking plate better?

Title: Re: No overflow on toilet cistern?
Post by jazzyman on Jan 14^th, 2015, 6:27pm

In the end I decided to replace the toilet cistern complete with a new syphon valve, because there were condensation issues with the old cistern.

I used a Dudley Tri-Shell cistern which came with a Dudley Turbo 88R syphon valve. However, I have the same problem the internal overflow comes into operation when the cistern is full more or less to the top. I contacted Dudley and they said a 7.5" syphon valve should be fitted. How do you measure a syphon valve?

The new valve is pictured below, is this a 7.5" or a 9.5"?

Title: Re: No overflow on toilet cistern?
Post by thescruff on Jan 14^th, 2015, 10:03pm

reconnect the overflow pipe. or buy a flapper type flush valve.

The pic show a 10" siphon

Title: Re: No overflow on toilet cistern?
Post by jazzyman on Jan 14^th, 2015, 11:48pm

Dudley are insisting that the siphon that I have is a 7.5", also found a mark on the syphon indicating that it is a 191mm, which is 7.5".

How are siphons measured?

Title: Re: No overflow on toilet cistern?
Post by thescruff on Jan 15^th, 2015, 10:14am

From the flange at the bottom to the seam at the top

Title: Re: No overflow on toilet cistern?
Post by CWatters on Jan 18^th, 2015, 11:47am

Is there a code on the packaging? See table..

http://www.thomasdudley.co.uk/bathroom/cistern-components/turbo-88-syphon.html

The internal overflow should start when water reaches the red line I've added. However if the water pressure is very high and the flow rate into the cistern is very high the water level can rise higher.

[gallery]CWatters/1421582494.jpg[/gallery]