Shower pump flow switch

[Mike Barnes]

My Stuart Turner monsoon shower pump, installed about ten years ago, sometimes continues running after the water flow stops. To stop it I have to give a few sharp taps with a hammer near the (magnetic?) switch that I can see clamped to one of the pipes. But the pump is sticking on more and more often, and is starting to become a real nuisance.

When I shone my torch in there to read the label for this posting, I saw that there's another switch clamped to another pipe at the back. I'm assuming the switches are connected in parallel so either of them could be sticking on and I might have been banging away near the wrong one.

Is it likely to be a magnet or a switch that's sticking?

The pump is not at all easy to get at, so any advice that would help me quickly home in on a solution would be appreciated.

[Capitol]

IME this indicates that the magnet has rusted and split the nylon holder. The resulting mess is too wide to slide in the housing.

[Roger Mills]

Chances are that there are two reed switches (one for hot and one for cold) which are triggered by magnets attached to floats - which move up when there is flow. The two switches will be wired in parallel so that flow in either hot or cold (or both) will turn the pump on.

It's possible that there's some crud caught in one of the float chambers which is stopping the float from dropping when the flow stops. In order to sort it, you really need to dismantle the float chambers and clean them out.

If you can get at the wiring, you could disconnect each switch in turn to see which one is problematical. [You'll probably find that it will work ok on one switch anyway because it's rare - in our house at any rate - to operate the shower on fully hot with no cold, or vice versa.]

[Mike Barnes]

Update

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The pump stuck on again tonight and the hammer wasn't having any effect. I disconnected each switch in turn to see where the problem was and in neither case did it make any difference. It seems that the relay in the control box is the problem and giving that just the slightest tap fixes the problem.

In theory I could replace just the relay but there's some blackening on the circuit board so I'll look into getting a complete new board.

Thanks for the ideas.

[Mike Barnes]

Helpful response from manufacturer. New board ordered and fitted, all well. Total cost £46 which is non-trivial but a lot cheaper than a new pump.

Thanks to all who replied.