Advice needed from specialist in pump installations All aspects of plumbing questions and answers, help, tips and information

[crash87]

Please help, I have purchased two different pumps, and I don't want to get the 3rd one wrong too.

I need 5 litres in 15 seconds in order to operate this smart toilet:

https://uk.homary.com/item/modern-black ... 42877.html

I live in a flat in Central London - old building, water pressure is not good. Can someone please advise me which pump type to purchase.

Thank you!

[stoneyboy]

Hi crash87,
As a general guide you will need to acquire a single impeller 3bar pump. If your existing system cannot supply 20l per minute it won’t matter what pump you fit, it won’t be able to provide more water than the supply volume.
Test the water supply yourself by putting a measuring jug under a bathroom tap, open the tap fully and time how long it takes to get 1 litre. If this is more than 3 seconds you will have to find an alternative solution.
Regards S

[crash87]

Thank you for your reply.

How about this pump, with a 19Litre tank. I only need 5 litres per flush, it only needs to run for 15 seconds, so the water in the pump tank should do the job, right?

https://www.expondo.co.uk/hillvert-self ... w-10090090

Hi crash87,
As a general guide you will need to acquire a single impeller 3bar pump. If your existing system cannot supply 20l per minute it won’t matter what pump you fit, it won’t be able to provide more water than the supply volume.
Test the water supply yourself by putting a measuring jug under a bathroom tap, open the tap fully and time how long it takes to get 1 litre. If this is more than 3 seconds you will have to find an alternative solution.
Regards S

[stoneyboy]

Hi crash87,
I would not like to advise you about the suitability of the pump you gave a link to. It looks like that particular pump could supply 60 litres per minute, this could be way in excess of the operating capacity of your chosen loo.
Suggest you seek advice from the loo manufacturer.
Regards S

[crash87]

Thanks for your reply.

I have bought my 3rd pump:

https://www.tridentpumps.co.uk/product/ ... ting-pump/

What I can't figure out is if I need a volume of 5 litres in 15 seconds - is it the case that the longer the output hose, the more chances I have that the pump has 5 litres of water to boost ? Thanks!

[stoneyboy]

Hi crash87,
Within the constraints of a domestic house the length of the input and output hoses will not change the volume of water pumped. With your latest pump, pipe diameters of 22mm should work ok provided there is suitable supply flow volume. If the pump is trying to pump more water than is available you are likely to get cavitation.
Regards S