Pump Head
Pump head is the total resistance a pump must overcome, expressed in metres of water column: the static height it lifts, plus friction losses through pipes and fittings, plus the residual pressure required at the delivery point.
Why it matters on an MEPF project
Flow and head together are the pump's job description; get head wrong and the pump delivers the wrong flow at the wrong efficiency point. The classic site errors are forgetting friction (long runs, elbow-rich routes) or forgetting residual pressure (the shower needs pressure, not just arrival), yielding pumps that "work" while starving the far fixture — or oversized pumps throttled forever by a half-shut valve.
Head is also where energy hides: every metre of unnecessary head is permanent power, and a pump forced off its best-efficiency point wears fast (cavitation at one extreme, recirculation at the other). Right-sizing plus VFD control where demand varies is the modern pattern — 1 bar ≈ 10.2 m of head is the conversion that ties pump talk to pressure talk.
How it's specified in practice
| Parameter | Typical / working position | Governing reference |
|---|---|---|
| Static head | Vertical lift, source level to delivery level | geometry |
| Friction head | Pipe + fittings losses; rises steeply with velocity | hydraulic tables |
| Residual head | Pressure required at the worst outlet | fixture requirements |
| Conversion | 10.2 m ≈ 1 bar | physics |
Common mistakes
- Sizing to static lift only — friction on long runs is the pump's real enemy.
- Ignoring suction conditions; NPSH problems masquerade as "bad pumps".
- Permanent valve throttling instead of correct selection or a VFD.
- One duty point for a system whose demand swings all day.
Related on this site
Frequently asked
How do I calculate the head my pump needs?
Static lift + friction (from pipe size, length, fittings at design flow) + residual pressure at the critical outlet. Our pump-head calculator does the arithmetic and returns head plus power.
Why does my pump cavitate?
Suction-side starvation — insufficient NPSH from lift, undersized suction pipe, or hot water. The fix is suction design (lower lift, larger/shorter suction, flooded suction), never a bigger impeller.
Standards referenced: hydraulic design practice · NBC 2016 Part 9 (system context)