Can a Porcelaine syphon be replaced with a plastic syphon ?

[andyaveyard]

Firstly I'll say hi to you all !

We have an old toilet (close coupled) and recently we've been experiencing flush problems, on flushing the water level rises to 2" below the pan top and then slowly empties but not all the 'material' is flushed away, loo paper etc gently swirls round the pan and remains there until the 2nd flush. (If I tip a bucket of water into the pan it runs away fairly quickly).

I've checked for blockages and have used a great big plunger, a gas cannister unblocker and also a flexible metal thing but all to no avail. The syphon in the cistern is one of the old porcelaine types and the piston (not sure what to call it) inside seems to drop lower thasn it used to.

Is it possible to replace the existing large porcelaine syphon with a new plastic version ?

Thanks in advance.

 

[chrishutt]

It should be possible if the existing syphon just sits in a hole in the base of the cistern, held in place with a back nut. You could even fit a flush valve of the non-syphon sort. Alternatively you might be able to replace the diaphragm in the existing syphon.

 

[andyaveyard]

I'm not sure if you can make it out from the pic below, but the syphon has a large base and one of the bolts go through it to fasten the cistern to the pan, could a modern syphon still be used ?

 

[chrishutt]

one of the bolts go through it to fasten the cistern to the pan

Are you sure the same bolt goes through to pan? If so it could be tricky to adapt it to modern syphon, etc. Probably more sensible to think about replacing whole WC.

 

[andyaveyard]

Hi Chris, yes the bolt does go straight through and has a badly corroded wing nut underneath, doesn't sound too promising does it ?

 

[cozzmic]

You have either got a choke as the water level rises in the pan to 2" from the rim or you have an old syphonic pan and cistern. Can you take a photo of the side view of your wc. If it is a syphonic it'll be a suction pipe connecting inside the china syphon to a second trap to lower the air pressure in it and make the flush work. If it's faulty your pan will fill up and then maybe empty itself when its near the top of the rim. Or there will be a small pipe out of the cistern in the middle to connect to the second trap.

 

[JohnD]

You said:

recently we've been experiencing flush problems, on flushing the water level rises to 2" below the pan top and then slowly empties

How was it working before this?

 

[chrishutt]

Yeh, I didn't read the post properly when I first replied. I agree - you seem to have a syphonic WC which may have a device in the syphon outlet, which you may break when you take the cistern off the pan (lift it off carefully)! This device may be a tube with a venturi around it and may need replacing (but you can't get replacements, although I have one)! Simplest to replace whole thing.

 

[Gasguru]

Looks like a dual syphonic pan.

From memory a 1/2 copper tube connects the second? bend in the pan to the syphon.

I don't think you can replace the syphon with modern plastic type.

You may find the sealing washers/gaskits between the cistern and pan are defective allowing pressure to escape.

I recall using plumbers mate as a new "washer" - that was 4 years ago and assume its still working (couldn't replace pan as expensive tiles fitted around pan base)

 

[JohnD]

Is it possible to use e.g. LSX to form a new sealing "washer", but without gluing the parts together?

 

[Gasguru]

I think there is a big uneven gap between pan and cistern - hence need for something thick!