Boosting pumped pressure

[adbase]

I live most of the year on a tiny Caribbean island with no mains water. I collect rain in a 25,000 gallon cistern which is then pumped to the taps. But the house is build against a hill top.

My water system is as illustrated below enabling the domestic water and garden irrigation to be served by separate pumps:

Each pump with its own pressure vessel is plumbed so that either pump can be isolated (with cutoff valves) and then by opening the crossflow valve the remaining pump can be made to do both garden watering and domestic supply.



But the pressure — largely due to the water needing to be pushed up 25 feet from the basement— is a bit pathetic.



My question:

Would opening the crossflow valve to effectively merge the separate systems into one make much difference? Might there be any problems as two pumps are trying to pressurise two vessels at the same time?



I have two more options:



I can recombine the two water supplies at the garden level which is 25 feet above the pumps incorporating check valves. So might this be a way to boost the pressure easily for the garden?



And/or I can use a plastic shipping barrel as a water butt raising it slightly above the bib tap level. I figure this could be plumbed in parallel (with check valves) to add a bit of pressure in gravity head (220 litres at maybe a couple of feet).



Any suggestions what might work best?

 

[ShaunCorbs]

What’s the rating on the large pump as tbh 7.5m head so 0.75 bar so you need a pump around 21m capacity head tbh the more the better eg 31m would give you 3 bar at your outlets roughly

Your cross flow valve won’t do anything

 

[adbase]

What’s the rating on the large pump as tbh 7.5m head so 0.75 bar so you need a pump around 21m capacity head tbh the more the better eg 31m would give you 3 bar at your outlets roughly

Your cross flow valve won’t do anything

Here are the plates from the two pumps.



My builders put a ridiculously small vessel on the large pump in the false belief it is the pump and the not the vessel that provides the pressure so it was cutting in and out like a fiddlers elbow. I also wanted backup in case of pump failure so at the time I gave the big pump a new larger vessel I used the old small vessel with a new small pump to rejig it. This also meant my portable generator could power the smaller pump during regular outages.

The pressure is good enough for what we need but i shipped a self watering system for the growing house and i just dribbles rather than squirts so I wanted an easy solution.

 

[ShaunCorbs]

Yea good pump but not suitable for drinking water as it’s a cast body

But you have 60m of head and I’ve personally got one working pumping up 62m so you should have more than enough head

The cistern is above that room eg with the pumps in / on the same level ?

 

[adbase]

Yea good pump but not suitable for drinking water as it’s a cast body

But you have 60m of head and I’ve personally got one working pumping up 62m so you should have more than enough head

The cistern is above that room eg with the pumps in / on the same level ?

The cistern is behind the back wall. So the base is at the floor level and depending how full it is the water level is 13 feet above these pumps.
We like to live dangerously out here so we drink this water but it goes through a sediment filter for Sahara dust and a UV purifier. But hey-ho we all die.

Any ideas to boost the garden pressure. If i recombine the different outputs would the pressure double?

I doubt 31 stone in weight of water a couple of feet above my garden tap will add much pressure but I don't need a lot of a boost.

 

[ShaunCorbs]

Tbh the pump should provide what you need how old is the pump ?

 

[adbase]

The cistern is behind the back wall. So the base is at the floor level and depending how full it is the water level is 13 feet above these pumps.
We like to live dangerously out here so we drink this water but it goes through a sediment filter for Sahara dust and a UV purifier. But hey-ho we all die.

Any ideas to boost the garden pressure. If i recombine the different outputs would the pressure double?

I doubt 31 stone in weight of water a couple of feet above my garden tap will add much pressure but I don't need a lot of a boost.

The bigger pump is about 4 years old, the smaller one which is primarily for the garden is only about 6 months old. I also split them so the sediment and UV filters don't take away any garden pressure after all we don't need clean water for flowers and veg.

 

[ShaunCorbs]

And there’s no restriction all the way to the end of the outlet eg hose ?

 

[John.g]

If you have a pressure gauge on the pump discharge can you shut the discharge valve and check for 4.2bar or whatever the pressure switch is operating at.

There would be some advantage in raising the small pump by 25ft, 0.76M, don't know what flowrate you expect for the self watering system but from the pump curves IF the flowrate was 1.5m3/hr (25LPM) at a generated head of 2.5bar then you should achieve ~ 1.8m3/hr (30LPM) (+20%) by raising the pump 25ft.
What kind of performance are you getting from the big pump by passed to the selfwatering system?.