Toilet seems to have a weak flush

twopenny

I have the same problem and cleared all the incoming water vents and the outgoing pipe.

In my case it was that someone had adjusted the ballcock to allow less water in (water meter?) and I adjusted it but it still leave the paper sometimes. Happily everything else is disposed of

With the water seeming to come up to the correct level it should be elsewhere. There is a mark inside the back of the cistern that should give you a maximum level. Have a look for one.

fenwick458

I've often found toilets with weak flushes have a very indirect route back to the main soil stack. it's often the extra toilet added  that  has 15m of pipework and 5 x 90 degree bends that just doesn't flush properly

coffeehound

OP implies it was okay in the past

danrv

Niv said:

If its been the same set up and nothing has changed in that time then my guess is its the diaphragm that's gone. You can get replacement ones, but I wouldn't bother, I would just replace the unit .
Something like this:
https://www.screwfix.com/p/flomasta-dual-flush-siphon-95mm/179FY?tc=YT4&ds_kid=92700055281954514&ds_rl=1249404&gclid=EAIaIQobChMIwoPgiLm87wIVCKp3Ch1opwY4EAQYAyABEgJTQPD_BwE&gclsrc=aw.ds 

It’s quite possibly this.
I replaced the siphon in my low level cistern loo.
Quite straight forward with this type and not too difficult, I’d imagine with a close coupled one.
Just need to empty the cistern, detach the water feed and decouple the units.
You can usually tell if the diaphragm is worn as the suction is intermittent or weak.

coffeehound

@sand_hun any success?

sand_hun

Apologies for the delay in responding.

@Jeepers_Creepers said :

Ooh, that's interesting. When you flush a syphon toilet like yours, the cistern should really empty pretty much fully, leaving just around a half-inch of water in there, and then it refills.

----------------

I have just tested this and observed that the cistern doesn't empty pretty much fully. The water level does indeed drop when the flush is pressed but I'd say there's still about 4 to 5 inches of water left in the cistern - then it slowly starts to fill back up again to sit at a level just below the overflow pipe, as per the picture.

 

Jeepers_Creepers

sand_hun said:

Apologies for the delay in responding.

@Jeepers_Creepers said :

Ooh, that's interesting. When you flush a syphon toilet like yours, the cistern should really empty pretty much fully, leaving just around a half-inch of water in there, and then it refills.

----------------

I have just tested this and observed that the cistern doesn't empty pretty much fully. The water level does indeed drop when the flush is pressed but I'd say there's still about 4 to 5 inches of water left in the cistern - then it slowly starts to fill back up again to sit at a level just below the overflow pipe, as per the picture.

4 to 5 inches is around half the cistern capacity? No wonder your flush is weak.

That's a weird one - not sure why it should stop in what is effectively mid-flush. Could the diaphragm be stiff or something, which is making it more difficult for water to flow past? Or is there air getting in around the doughnut?

Ah, is it a dual-flush type? https://www.raygrahams.com/products/117689-opella-dual-flush-8-inch-toilet-syphon.aspx  This should do a normal flush if lever pulled and released, and a short one if pulled and held (I think I got that the right way around).

Also, if you look at the pic in that link, you'll see a couple of plugs in the side. If these are missing, then air will get pulled in as soon as the water hits that open hole - and the flush will stop. Quite likely that's your issue - could you have a looksee?

sand_hun

Ugh. Siphons, dual-flushes, cisterns, doughnuts, diaphragms, who'd have thought a toilet could be so complicated?

This is how the cistern water level looks after it's been flushed (just before it starts to fill back up). As you can probably see, still a few inches of water in there. I don't know about the flush type, will do some further investigation tomorrow based on the various replies that have been posted here.

Jeepers_Creepers

Tsk, this ain't difficult, but you may lose your phone as you slip it down the inside of the cistern to take a sideways photo of your syphon...

See this?

That's the same make as you have. See the two plugs the red arrow is pointing to? These are used to determine the flushing volume. Can you find out - by touch if necessary - if these are there, or are they holes?

Jeepers_Creepers

See this: http://www.thomasdudley.co.uk/images/pdf_instructions/TDCF 2451 Iss J Cistern Installation Instructions.pdf

These plugs - assuming you have them - make a large difference to the flushing capacity, eg from 6 to 9 litres.

The daft thing about many of these water-saving devices is that they don't. Because if you need to flush twice to shift a jobbie, then, you know...