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Are there any clear water flow/pressure pump differences?

Think it's time to replace the flow pump i've on the roof, that takes in water from the roof clear water storage tank and sends it down the pipes with pressure so we get nice flow in the taps around the house.

Thing is, the shop always ask whether it's a ' flow ' pump from roof downwards, or a cistern pump that sucks from below ground and pushes water up high to storage tank. Are there real differences in such pumps?

Am aware that clear water pumps vary by pressure amounts measured in bars, which would explain how high the water can be pushed up. But from the way shops speak about either pumps it's as if they're constructed completely different and cannot be interchanged.

I've done my research on google but none meaningful hinting the differences in types-which helped me doubt the shops more. 

Maybe someone knowledgeable can bust this myth for me.

Cheers everyone

Random google img link to help you picture which sort of pump am referring to.

4 Answers

  • 3 months ago
    Favorite Answer

    A given amount of horsepower can deliver any combination of volume and pressure. The pump design controls those values. You do not want a pump that delivers too much pressure at the expense of less volume, or vice versa. Of course, overwhelming horsepower can deliver both pressure and volume but at a greater cost, but you dealing in a situation where the cost has been optimized to minimum. So somebody has figured out the correct designs for your situation. Minimalist, environmentalist, lowest impact, etc. concepts. Your argument is just a more expensive, bigger pump and not worry about it. That would probably work better.

  • Anonymous
    3 months ago


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  • y
    Lv 7
    3 months ago

    Huge difference in one pumping it up, and one used for pressurizing your house system.

    • ...Show all comments
    • Unfortunately gravity isn't enough even though it's a positive head system (hence have greater than 600mm vertical height from the bottom of the tank to the first outlet, if we take for example the washer it simply complains of lack of flow and doesn't start washing. Apart from that the shower heads

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  • 3 months ago

    A "lift pump" that is located above the level of the water source must be able to also pump air, or have some means of initially filling the pump with water if is dry.

    Or, it has to be a submersible type where the pump is in the water cistern or well, so always full of water.

    With a high level tank and the pump below it, the pump is naturally kept full of water so a simple centrifugal impeller type (that could not pump air or self-prime) works perfectly.

    • Very true with regards to priming. But that can easily be sorted for a cistern (above water) pump even if it not self prime capable, by having a non return valve and it's primed manually once by topping it with water. Unless cistern empties that is, as then air is obviously introduced. Thanks 

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