Can I do anything to boost flow rate into my Roca cistern?

[Indie66]

Hello,
First post, be gentle! Anyway, here's my issue. I have a Roca The Gap D-Trit close-couple toilet with integrated macerator in my secondary bathroom. In all it's a great solution for a problem location for a bathroom. However, the cistern has a typical european style side inlet pipe, and has what looks like a miniscule diameter (maybe 10mm external, god knows internal, and the docs have no info on it).
My water supply is all gravity fed upstairs, and as such I don't have a tonne of pressure anyway. When trying to force it through this tiny pipe, the flow into the cistern is basically a dribble at best. It takes well over an hour to fully fill the cistern.
I've already had it apart and removed a restrictor from the inlet, which made a small improvement. My question is whether it's feasible to replace the entire inlet pipe with a wider diameter pipe? And would it make a difference if I could? I've also investigated an inline pump but I'm not convinced I even have the flow rate to trigger a pump flow switch! It's clearly designed for a much higher water pressure than a typical UK bathroom, and I really want to make this £1500 toilet work better!

 

[Robooo]

Plumberparts did a video on an indirect combination water heater which head really low head. They installed a pump to fill the tank on top of the water cylinder faster and a sensor on the water tank in case the water level would run low. I think, that might give an idea you can incorporate..

 

[Robooo]

Not sure about increasing the pipe diameter but if you raise the water storage tank higher that gives you more water working head aka more pressure.

 

[John.g]

Can you remove the cistern top and post a photo of the "ballcock" assembly, if it is the traditional type then you can change the nozzle from a high pressure to a low pressure one (larger diameter nozzle), might give some improvement.
It takes exactly 3 minutes to fill my gravity fed (upstairs) cistern, but cant remember if it has the low or high pressure nozzle.

 

[Indie66]

Can you remove the cistern top and post a photo of the "ballcock" assembly, if it is the traditional type then you can change the nozzle from a high pressure to a low pressure one (larger diameter nozzle), might give some improvement.
It takes exactly 3 minutes to fill my gravity fed (upstairs) cistern, but cant remember if it has the low or high pressure nozzle.

It looks similar to this, but with a side-inlet rather than a bottom inlet.

I have another two toilets upstairs, both of which fill completely fine, and one is a brand-new Saneaux cistern, so it's not like everything else is old imperial measurements or anything. Seems to be specific to the Roca pipe inlet.

 

[gpbeck]

This is a servo valve that needs high pressure to operate properly. It should be pretty simple to swap this valve for a low pressure valve from a local merchant (asking their advice). And change the pipe at the same time.

 

[John.g]

The pipe ID can make a huge difference.
Assuming a 2.5M head then 1M of 6MM ID pipe will flow 5.7LPM but 4MM ID will only flow 2.0LPM.

 

[Ben-gee]

How accessible is pipework, it might be simple to change so that it is fed from the mains instead?

 

[Indie66]

This is a servo valve that needs high pressure to operate properly. It should be pretty simple to swap this valve for a low pressure valve from a local merchant (asking their advice). And change the pipe at the same time.

That's helpful to know, thanks!

 

[Indie66]

The pipe ID can make a huge difference.
Assuming a 2.5M head then 1M of 6MM ID pipe will flow 5.7LPM but 4MM ID will only flow 2.0LPM.

Wow yeah - I think this will be my first strategy before exploring whether I need to change out the entire float valve system.