TOILET SIPHON AND 11/4" FLUSH PIPE:

[RONCHAM]

Hi to all -

I was thinking to change my toilet siphon, a (theoretically) easy job. But my flush pipe is 11/4" or 32mm diameter and most siphons are designed for 11/2" (38mm) flush pipes. Presumably my toilet is not so unusual it won't accept both sizes of flush pipe?? I appreciate I can buy a new flush pipe (dearer than many siphons!) but alternatively could I reduce from 38mm to 32mm (possibly with a single fitting) and will the flush still be effective??

Any advice or help will be appreciated.

Regards.

 

[RONCHAM]

My toilet and low level cistern don't bear any name and are at least 20+ years old. I'm wondering if toilets and cisterns (and siphons) of that age could only accept 32mm flush pipes, does anybody know?? - there's certainly no reducer at the siphon end. But I don't think you can get a siphon now that directly takes a 32mm flush pipe? At worst I can dismantle and reassemble if necessary buy I'm worried about introducing a leak worse than I have now.

Not so long ago questions would get fairly quick responses from guys willing to offer advice but maybe those guys have now hung up their spanners and enjoying retirement? But as before any advice or help will be appreciated.

Regards.

 

[Hugh Jaleak]

If the bigger syphon tail will fit your cistern, then I'd go for that, and just change the flush pipe and flush cone to suit. (Assuming as you say your pan will accept a 38mm flush pipe and cone.)

 

[RONCHAM]

Thanks for your quick reply - of course that's the burning question! Especially the siphon tail fitting my existing cistern - the fact there's no reducer to 32mm makes me wonder. If it does fit I could presumably then use a 38mm to 32mm at the cistern end if the pan won't accept 38mm? I was hoping an old school plumber had come across this in the past. We have a back-up toilet on the side of our house if things go pear-shaped but don't fancy using until we have warmer weather! Thanks again.

 

[terryplumb]

What exactly is leaking ,and why do you need to change anything ?

 

[RONCHAM]

Hi - it's leaking slightly on the underside of the cistern (on the outside). It's a bit messy with some kind of sealant and presumably a washer or just the backnut. On the inside of the cistern there seems to be a kind of squishy doughnut of sealant - isn't it normally just a flat rubber washer (or a domed washer?) - some say use use silicone sealant in addition to the washer, manufacturers say it's not necessary?? Because it's all a bit messy I'm worried that if I dismantle it I may not be able to reassemble and make it leakproof. By the way the cistern is marked August 1970!

Regards.

 

[terryplumb]

I would take the siphon out and fit a new washer on the inside of the cistern. NO need for a washer outside .

 

[RONCHAM]

Hi -
Thanks for getting back so quickly. Yes, I think you're right though I'm a pessimist and always expect the worst! Is it a simple flat washer inside the cistern and what's your opinion on using sealant as well (under or around the washer)?? And IF the cistern would accept a new siphon with 38mm outlet is there a tapered cone ring from 38mm to 32mm so I can retain the existing flush pipe? Or could I use a 38mm to 32mm push-fit reducer?

Regards.

 

[terryplumb]

Yes ,inside cistern the siphon washer is a thick flat washer. Never needed any sealant in or outside cistern.
Where the flush pipe goes into your pan inlet ,is there an internal or external flush cone joining the two ?
Pics would be helpful.
How have you determined the outer diameter of the flush pipe if it hasn't been disconnected ?

 

[RONCHAM]

It's an internal cone into toilet pan inlet. I'm fairly good at maths so I measured the outside circumference which gave an outside diameter of 38mm giving an internal diameter of approx. 32mm (I believe plastic pipe is referenced by its internal diameter?). I've attached a couple of photos.

Regards.

 

[RONCHAM]

Sorry for the delay, took a while with the photos>

 

[RONCHAM]

Hope you don't say it's 1½", I'm (fairly) sure it's 1¼".

 

[terryplumb]

1 ¹/² inch pipe is 40mm outside diameter.
1¹/⁴ inch pipe is 34mm ( ABS pipe for solvent welding is a couple of mm larger ,but your flush pipe isn't gonna be ABS)
If your pipe is 38mm outside diameter it should join into a 1¹/² inch siphons compression fitting no problem.

 

[RONCHAM]

Thank you Terry for all your help and advice. I thought I was familiar with1½" pipe and this looked smaller - I attached the photo with the ruler because the photo of the pipe entering the pan seemed a bit deceiving. I think I'll bite the bullet and go for it - it's not a great expense (in fact some washers are nearly as much as the full siphon kit!). I won't go for the £5 cheapos though some are favourably reviewed - but Fluidmaster seem well respected. Thanks again.

Regards.

 

[terryplumb]

The pic with ruler appears to show an outside diameter of 30mm ??
What exactly is the circumference ??