Roger Mills wrote:
In an earlier contribution to this discussion,
Mark BR wrote:

Can a plumber give me a simple answer to what I think is a simple
question?
I'm working with a building in Thailand to improve the water supply.
Currently we have a pump and pressure tank that can just get up to
2.5Kg/cm (2.5 bar). This pressure is just enough. Problem is when it
reaches pressure it switches off and only comes back at 1.7 bar, not
enough for most rooms. So we get a varying water supply from a
trickle to a surge. If we leave the pump on continuously we use far
too much electricity.
We have a lovely electric pump, 8 amp so plenty of power, and a
header tank 4 metres above the pump.

Can I just change the water pump part - is that the impeller?

If I change it for a pump that can get up to 3.5 bar is that the same
as a pump that can give a 35m lift?

Thanks,

You say the pump switches off at 3.5bar - so this is probably a
function of the pressure switch rather than the pump per se. Maybe
the pump itself is capable of more than this. Can the pressure switch
be adjusted or replaced.
Is there an accummulator in the system which can maintain pressure as
the water is drawn off?

It is the pressure switch that turns the pump off, but the maximum the pump
can get the pressure to is 2.5 bar even if we left it switched on for a few
months!

We do have a pressure tank that keeps the pressure up for a few minutes, up
to 6 minutes but then it slowly drops.

Thanks for the comments
--
Mark BR