Are most domestic toilet siphons 1.5" or 2" connections? Or is there wide variance?

[AVR2]

I've never done any toilet DIY before, but I need to replace a siphon in a close-coupled cistern. Googling around, none of the usual DIY suppliers seem to indicate whether their siphons are for 1.5" or 2" connections, but most of the close-coupling kits with sealing rings seem to be for 1.5".

Is there a rule of thumb here, or do I just have to get the old siphon out and measure the connection size?

 

[terryplumb]

Show us a pic from inside the cistern. Some valves come with a conversion washer to enable the valve to be fitted to a cistern of either hole size.

 

[dilalio]

Get a fluidmaster.

 

[AVR2]

Photo below. Not sure how helpful it is, if at all.

 

[terryplumb]

Looks like 1 1/2 inch.

 

[AVR2]

Thankyou!

 

[just pumps]

Looks like it may be a Thomas Dudley, shame it isn`t a two piece.

 

[Hugh Jaleak]

To be honest, I've never come across a 2" siphon, they've all been 1.5", only when the new style flush valves came about did I discover there were 2 sizes!

I'd safely say that's 1.5", but check the height, as siphons do come in different heights. If replacing the lot, do yourself a favour and fit the Dudley Turbo siphon, so much easier to sort out next time it needs a new washer.

 

[dilalio]

Get a fluidmaster.

I repeat!

https://www.fluidmaster.com/united-...-fluidmaster-pro-universal-dual-flush-syphon/

 

[AVR2]

OK, turns out the hole in the cistern is 2" but the siphon outlet is 1.5" ID.

Looks like the flange and washer on the siphon itself take care of filling the gap? I won't need to buy any other kind of adapter?

 

[terryplumb]

Yes the conversion washer is basically an adaptor.

 

[AVR2]

Thankyou!

Final dumb question - the rubber doughnut in a close-coupling seal kit sandwiches between the metal plate and the toilet bowl, not between the plate and the cistern?

 

[polesapart]

Yes

 

[AVR2]

Ignore - found a YT video that covered everything I needed to know.