cistern internal overflow too short

[Addis]

I have a concealed cistern with an internal overflow. The problem I have is the height of the overflow pipe is too low, the water level is a couple of litres lower than the maximum and the flush is poor.

As a test I blocked the overflow and lifted the water level to the maximum, the flush is much better.

What I need to do is to extend the overflow height by about 1 inch. I thought of putting a solvent weld coupler on it but I cannot find one that is the correct diameter. The overflow pipe is not adjustable or removable.

The external diameter of the overflow pipe is 28mm, can anyone suggest a way of extending the height?

 

[leakydave]

Did you just fit a new syphon? If so you fitted one that was too low. Thomas Dudley Turbo available in 8" 9" and 10" overflow height.

 

[Charnwood]

Thomas Dudley Turbo available in....

7, 71/2, 8, 81/2, 9, 91/2, 10, inch fixed height and an adjustable version, adjustable from 71/2 to 10 inch. Dudley Turbo models include Turbo 11, 44 and 88.

I don't see where the OP said it was a syphon.

Fit a flapper valve. Syphons are only good for exhibitting in a museum.

 

[Addis]

It is a syphon flush and it came with the cistern so I don't understand why it is too short in the first place, perhaps whoever fitted it cut it shorter!

Would my idea of gluing an extension to it not work, I'd rather do that then replace the whole syphon.

 

[seco services]

Syphons have an inbuilt overflow.
So why not buy a plug and remove the external overflow.

 

[CBF]

Syphons have an inbuilt overflow.
So why not buy a plug and remove the external overflow.

i'm guessing the title of the thread as well the OP's first 9 words, just may give a clue

 

[seco services]

i'm guessing the title of the thread as well the OP's first 9 words, just may give a clue

No enlighten me.

 

[CBF]

way to go to make myself look a complete ****, but then i guess a few are smiling now

 

[seco services]

way to go to make myself look a complete ****, but then i guess a few are smiling now

go on.

 

[CBF]

yes i know i read it wrong so my apoligies, 'note to self' engage brain before typing

 

[seco services]

yes i know i read it wrong so my apoligies, 'note to self' engage brain before typing

It's late, i won't say nothing.

 

[Charnwood]

What I need to do is to extend the overflow height by about 1 inch.

Why?
You said filling to the spill-over level the flush was fine, so all you need to do is set the inlet valve to cut off just short of the overflow spill-over. The few centilitres between that and max will make no difference.

 

[Charnwood]

If it is an internal overflow AND it’s a syphon, how was it cut too short?

I think we are getting confused by the OPs terminilogy.
I think he has a bottom connection overflow pipe.

If the OP could post a picture it would help.

 

[Addis]

Ok, my syphon is similar to this -

http://www.screwfix.com/p/fluidmaster-push-button-cable-dual-flush-valve/51173

but it hasn't got the height adjustment on the overflow pipe. If I fill the cistern just short of the overflow level I am about 2 litres short of water!

I need to lift the level of the overflow by about 1 inch to allow me to get the extra 2 litres of water needed to give a decent flush.

 

[rjm2k]

Are you sure you don't just need to adjust the flush rate on there rather than put more water in? There should be 2 adjustments, one for full and one for half flush. Or is the cistern emptying completely when you flush?