The Pump Term Maximum Head ... What Does It mean For A Submersible Pond
It is easier to talk of height rather than head when dealing with pumping
water in garden fish pond and waterfall situations. However the term head is
normally used and it actually means pressure. The term pump head comes about
because if you create in a glass tube, say, a column of water about 30 feet high
this exerts a pressure at the bottom of the water column of 30 feet of water
"head" and this is the equivalent of 14.7 psi (approx) which in turn is equal to
about 1 atmosphere pressure.
As far as we are concerned it can be directly translated to height to which
we want to pump water.
For any submersible pond pump the maximum head is the height at which the
pump delivers ZERO water. We know ... not very useful is it? So the next question
is a sensible one.
Why Is Maximum Head Useful?
If the term maximum head for a pond or waterfall pump has any practical use
then it is simply as a means to try to compare pumps in general. If we have
2 pumps within the same product or model series eg Hozelock Titan pumps with maximum
heads 3 metres and 4 metres then you immediately know
that the power of the one pump is more than the other and as such the
combination of height and water flow rate at different heights will be greater.
In other words quite simply the 4metre head pump is more powerful. However these
maximum head numbers do not help you understand what happens in a practical pond
waterfall situation. To further compound understanding problems it is not
possible to compare pumps with the same maximum head made by different companies
or even by the same company within different product series or model ranges.
See this article on comparing pond pumps .It
makes far more sense to state pump flows at different heads or heights as in the
Example Of Hozelock Cascade Garden Pond and Fountain Pumps Maximum Head
The Hozelock cascade 1000 delivers 500 lph at 1metre head or height or the
Hozelock Cascade product range model 4000 delivers 2800 litres per hour of water
at 1 metre head or height.
What happens If I Connect 2 Pumps In Series ... Can I Pump To A Greater
If we forget any practical difficulties just for a moment it is a fact that
if you use 2 identical pumps and one is connected to the other in series (ie a
pipe or tubing from the delivery of the one pump attaches to the suction pipe
inlet of the second identical pump) then in a broad sense you can pump the same
amount of water to twice the height any one pump will. In practice because of
efficiency losses the maximum head of the 2 connected pumps will be about 1.5
times the maximum head of a single pump.
If you connect the two pumps in parallel you will be able to deliver about
twice as much water to the same height as with one pump. Remember this if you
present pump is not quite big enough for your waterfall.
Summarising Maximum Head and Maximum Flow For Pond and Waterfall Pumps
Any submersible pond fountain pump or water fall pump will deliver ZERO flow
at the maximum pumping height and the same pump will deliver the absolute
maximum amount of water volume when no pipe or tubing is attached. This is the
equivalent of ZERO head. At any point between maximum head and zero head the
pump will deliver different amounts of water and this volume flow rate will
decrease in a non-linear way as head or pumping height increases.
If you want to deliver larger volumes of water at ever increasing height then
you will need more powerful pumps and this will mean the power consumption will
increase and your running cost will also increase. More often than not in a real
pond situation the running cost is far more important than the purchase price
and this is why it's important to be able to compare
pumps using concepts more than maximum head and maximum flow.