Convertible toilet syphon settings - possibly Dudley S90 Hydro

[Maldon]

Convertible 6/7/9 litre syphon in situ in our toilet, in house we moved into a few months ago. Looks most similar to the Dudley S90 Hydro, of models I've found online, but it's probably an older model. Can't see a brand on the syphon itself.

It works fine just now.

Hoping to make sure it uses the minimum amount of water and to not damage the syphon by adjusting it wrongly.

The toilet seems to be flushing with 7L at the moment. (Based on putting water into it from a bucket when empty just after flushing to measure.) I have no prior experience with these convertible syphons, but I think this one might be on the settings for 6L already. The white plug is sticking out a bit, but I don't know if that counts as 'out' according to the chart on the top of the syphon. Nor what the flap is that may be closed or open.

Is there someone familiar with this type of syphon who'd be able to advise based on the pic?

Cheers

 

[ShaunCorbs]

Does it empty all the water out the cistern or does it leave 4-5 inches in the bottom

 

[Maldon]

There are still a few inches of water left in the bottom when it's just been flushed.

 

[ShaunCorbs]

Aslong at the plug is in the side of the siphon and the top port is blocked off it can flush 9l depending on your cistern ball valve position

 

[ShaunCorbs]

If you want a lesser flush volume take the white plug out for a 6l flush (white plug should just pull out)

But it's a balancing act with flushing the solids away 😉

 

[Maldon]

The flap the chart is referring to, where's that though?

I guess the white plug is the one on the side of the syphon that's visible at the front on the right hand side under the water?

 

[ShaunCorbs]

The flap the chart is referring to, where's that though?

I guess the white plug is the one on the side of the syphon that's visible at the front on the right hand side under the water?

Yes and the flap is same side half way down the siphon

 

[Maldon]

So 'out' means removing the plug, not just pulling it further out of the syphon unit.
If the flap is open, presumably it's no longer flush (sorry) with the side of the syphon?

As the plug was in the unit and the flap flat, it looks like it's actually on the setting for 9L but the flush doesn't take up that much water.

 

[ShaunCorbs]

Yes remove the plug totally

And flap could mean a few things, like another plug or something you pull up etc

Depends on the water level in the cistern