How to replace a leaky WC Cistern syphon

[Alec_t]

slipping its sewer connection into the old sewer hole

That's where the fun could start, if pipe diameters/connections and alignments don't match. Good luck.

 

[siliconeseal]

That's where the fun could start, if pipe diameters/connections and alignments don't match. Good luck.

Question: There must have been a time when old model WCs like mine were replaced with the modern ones. Surely the modern ones are made to be backward compatible with the old WC sewer connections, or did they replumb the entire sewer drainage system?

@dilly :Yes, you too were right, bless your 'airy arse.

 

[dilalio]

Sometimes you can get onto the old cast iron soil inside... Sometimes you have to do it outside and run a new 4" soil through the wall to the pan.

 

[siliconeseal]

Right guys, I have accepted Alec_t's point about the danger of mismatch in the sewer connection. This kills the replace the WC idea and I'm back to mending the old one. But I have a new idea. To fix the syphon exit tube versus cistern exit hole mismatch I plan on using a expansion bushing like this one

2" X 1 1/2" BSP HEX RED BUSH 316 - Flow Technology LTD

Available in Stainless Steel 316. - In Stock,

flow-technology.co.uk

The bushing's inner female hole will mate with the Turbo88's 1 1/2" BSP exit tube. The bushing's OD is the same as the old syphon's exit tube. I will use the bushing with its hex part inside the cistern. I will use PTFE (water) thread sealing tape wrapped around the Turbo88's exit tube to make the Turbo88 - Bushing thread water-tight. I will need a thinnish 2" BSP ID neoprene washer to seal the bushing to the inside of the cistern hole. Please give me a link to a vendor which can supply me with such a washer.

On the outside of the cistern hole, I will use the following seal

Wirquin 2" Ribbed Toilet Doughnut Washer – Close Coupled Cistern Pan Seal - Pipescenes

Buy the Wirquin 2" Ribbed Doughnut Washer. High-quality rubber cistern-to-pan seal for close-coupled toilets. Stops leaks and ensures a secure, watertight fit.

pipescenes.co.uk

Finally I will use the retaining nut which I took off the original syphon's exit tube to secure & seal the bushing exitting out of the cistern.

What do you think?

EDIT: For the inner washer I will use this one:

VIVA Doughnut Washer Foam 2"

Features: Foam sealing washer for between toilet cistern and pan. Technical data: Material - Foam Colour - Black Thickness - 10m...DISCLAIMERThis product qualifies for next working day delivery provided it is in stock and your order is placed by 1pm Monday to Thursday. For full T&C's read...

www.mpmoran.co.uk

Can this washer be used for the outside too?

 

[Alec_t]

This kills the replace the WC idea

Not necessarily. There are various adapters, offset bends and flexies available.

 

[siliconeseal]

Not necessarily. There are various adapters, offset bends and flexies available.

Yes Alec. But to select the right one for a particiular job needs a trained and experienced Plumber, which I am not. I just want to finish the job with my limited skill set.

 

[siliconeseal]

Okay, I understand. Replacing the WC is the best option. I have selected a new one:

Wickes Cleveland Easy Clean Close Coupled Toilet | Wickes.co.uk

Wickes Cleveland Easy Clean Close Coupled Toilet

www.wickes.co.uk

which is slightly better spec than the Screwfix option selected earlier.

We come now to attaching the new WC to the sewer. Attached to this post are two images. The photo is of the existing sewer connection and the drawing is from the Wickes website detailing the new WC's outline. I draw your attention to the red boxed section of the drawing. Question: Where does the sewer connector pipe end, at B or at C?

In both cases B or C, the midpoint of the sewer pipe is 180mm from ground level.

Now look at the photo. I have placed a ruler on the ground next to the existing WC's sewer exit pipe. I have drawn a purple line horizontally to the right, at the 180mm mark. We can see that the adapter, labelled A, will either have to be removed and/or replaced with another adapter which is angled more counter-clockwise (in the direction of the drawn red arrow) to mate with the sewer pipe of the new pan.
Question: Where are adapters such as A available?
Question: Using the info given here, which adapter should I buy?
Question : Do I need a sealant to seal the WC's sewer pipe into the existing sewer connection/or into the adapter and the adapter into the sewer connection to prevent water/gas leakage? If yes then what sealant do you recommend?

Many thanks for your patience and assistance.

 

[HERTS P&D]

Pan Connectors | Wickes

Shop Wickes pan connectors for reliable connections between your toilet and plumbing, ensuring a tight, durable fit.

www.wickes.co.uk

But this looks like your best bet:

FloPlast Soil Pan Connector 14° - White | Wickes.co.uk

FloPlast Soil Pan Connector 14° - White

www.wickes.co.uk

Andy

 

[dilalio]

But this looks like your best bet:

Depends on the odds!

 

[siliconeseal]

Pan Connectors | Wickes

Shop Wickes pan connectors for reliable connections between your toilet and plumbing, ensuring a tight, durable fit.

www.wickes.co.uk

But this looks like your best bet:

FloPlast Soil Pan Connector 14° - White | Wickes.co.uk

FloPlast Soil Pan Connector 14° - White

www.wickes.co.uk

Andy

Thanks Andy, very helpful. Will the cistern have a side inlet like the existing cistern (see photos in post #32) or will I need a flexible hose like one of these? https://www.screwfix.com/c/heating-plumbing/compression-hoses/cat831678

Finally, please answer the question which I asked in post #52, namely
We come now to attaching the new WC to the sewer. Attached to this post are two images. The photo is of the existing sewer connection and the drawing is from the Wickes website detailing the new WC's outline. I draw your attention to the red boxed section of the drawing. Question: Where does the sewer connector pipe end, at B or at C?