Primary Water Flow Switches

Primary water flow switches

Reasons a primary water flow switch will fail to start:

  • Punctured / perished rubber diaphragm
  • Seized bearing plate spindle / out of alignment
  • Damaged / loose wiring harness
  • Switch contact faulty

A demand for central heating will activate the pump and a rubber diaphragm / spindle arrangement communicates to a micro switch assembly above, transmitting a signal to the printed circuit board for correct operation.

To test a primary water flow switch (on a demand):

Pressure differential type:
Visually assess whether bearing plate spindle is rising through gland nut, activating the micro switch assembly above.

(No spindle movement may be due to a perished rubber diaphragm and/or seized bearing plate spindle).

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