Water pump

Diaphragm pump basics

A demand pump starts when downstream pressure falls and stops at its pressure-switch setpoint. Self-priming height, flow, pressure, current, dry-run allowance and duty cycle are model-specific.

Choose for the fixtures

Add realistic simultaneous flow, then account for filters and heater minimum flow. A common 3 GPM / 55 PSI RV pump can draw up to about 7.5 A, but a bigger pump can create noise, cycling and excessive water use without improving the shower.

Install for service

Tank -> isolation valve -> coarse pump strainer -> flexible inlet -> pump -> flexible outlet -> system. Mount on a strong surface with the correct orientation/clearance, rubber isolation and accessible connectors. Never starve the inlet with a tiny hose or clogged strainer.

Electrical and control

Use the pump maker's fuse, wire and switch/relay instructions. Put a reachable master switch near living space and label it. Turn the pump off while driving, storing, investigating leaks or leaving the van unattended.

Build rule

If you cannot reach it, isolate it, drain it and explain its pressure/temperature or water-quality job, it is not ready to hide behind a wall.

CHAPTER CHECK

• I can explain the purpose and failure mode of each item in this chapter. • I know which manufacturer limit or water-quality claim controls my choice. • I added the valve, access, drain, measurement or maintenance task to my drawing/checklist.