Doctor Drivel wrote:
"Sparks" wrote in message
...
"Mark BR" wrote in message
...
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,

--
Mark BR

You could install a flow switch between the pressure vessel and the
rest of the plumbing, wired so when it detects flow, it turns the
pump on (So in parallel with the current pressure switch).

This way, the pump will always run when you are running water, and
only turn off when the pressure has reached the setting of the
pressure switch and there is no water flowing out of the pressure
vessel. I have this setup with my irrigation system setup, it seems to
work
well for me!

I was about to suggest that. You are right, a simple flow switch can
solve the problem and a little re-wiring around the pressure switch.

I had considered a flow switch but could only find information on little
laboratory systems - we have 1.25" PVC pipework. It would be easy to fit if
I can find one! I'll have to go to the shops on Wednesday - a 3 day holiday
out here for the new year!

--
Mark BR