Total Dynamic Head Calculator
Calculate the total resistance your pump must overcome to move water through your pond system.
Design your pond. Engineer your pond. Or check the pond you already have. Total Dynamic Head, or TDH, brings the different sources of resistance in a pond system together into one figure. It helps you understand what the pump is actually being asked to overcome.
A pump may be advertised with an impressive maximum flow rate, but that figure means very little until you know how much head the pond system creates.
Calculate Total Dynamic Head
KPE ENGINEERING CHECK
TDH is not the same thing as vertical height.
Your pump has to overcome elevation as well as resistance created by pipework, fittings and equipment. These losses are added together to estimate the total head the pump must produce at the required flow.
This is why choosing a pump from its headline maximum flow figure can produce disappointing results. The important question is what flow the pump can actually deliver at your calculated TDH.
What Your Result Is Telling You
The TDH result is the combined head that your pump system must overcome. The higher the number, the more work the pump has to do to move water through the system.
Static head
This represents the vertical lift in the system. Water being lifted to a higher return point requires the pump to overcome that elevation.
Pipe friction
Water loses energy as it travels through pipe. Longer runs, smaller internal diameters and higher flow rates can increase this loss.
Fittings and equipment
Elbows, tees, valves, filters and other components introduce additional resistance. A system with many components can therefore have considerably more resistance than its pipe length alone suggests.
Where Pond Designs Go Wrong
One of the most common mistakes is calculating the vertical lift and then treating that number as the pump’s total head requirement.
A pump operating against 2 metres of elevation may actually see substantially more than 2 metres of total dynamic head once pipework, fittings and equipment are included.
Another mistake is selecting a pump first and attempting to make the pipework fit around it. The better approach is to establish the required flow, calculate the system resistance and then examine the pump’s performance at that operating point.
Before You Buy Anything
Keep the TDH calculation with your target flow rate. Those two figures belong together.
The pump you eventually select should be capable of delivering the required flow at the calculated head, rather than simply having a large maximum-flow number on its specification sheet.
The Next Engineering Question
Now that you know the head your system creates, the next question is: what will the pump actually deliver at that head?
Build the Calculation From the System
If you have not already calculated the individual losses, use the supporting KPE tools:
→ Friction Loss Calculator
→ Fitting Loss Calculator
→ Pipe Size Calculator
→ Flow Rate Calculator