Flow, Pressure & Resistance

Lesson 5

Human Handbook

Explain how pressure difference, branch resistance and controls affect flow, and recognise what a measurement can and cannot establish.

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Three linked concepts

To understand a heating circuit, you need three ideas:

Flow — water moving through pipes. Spec sheets quote L/min; the equation in lesson 1 used L/s (0.2 L/s is 12 L/min)
Pressure difference — what drives the flow (the pump creates this)
Resistance — what opposes flow (pipes, bends, valves, radiators)

More resistance = less flow for the same pressure. More pressure = more flow through the same resistance.

Lesson 5

Human Handbook

Explain how pressure difference, branch resistance and controls affect flow, and recognise what a measurement can and cannot establish.

Read first

To understand a heating circuit, you need three ideas:

Flow — water moving through pipes. Spec sheets quote L/min; the equation in lesson 1 used L/s (0.2 L/s is 12 L/min)
Pressure difference — what drives the flow (the pump creates this)
Resistance — what opposes flow (pipes, bends, valves, radiators)

More resistance = less flow for the same pressure. More pressure = more flow through the same resistance.