Wickes Shower Pump - Electrical Question

[Clive Backham]

I am planning to fit a timed extractor fan into the bathroom. Ideally, it should only come on when the power shower is used. I have a Wickes Twin Impeller Shower Pump (product code 410042), and was hoping to wire the fan into the control board of the pump.

I was expecting to find a place on the circuit board which only becomes live once the pump is activated, but after some probing around with a multimeter, it seems that every potential place is already live all the time. Does anyone understand how this circuit board works, or perhaps have a schematic for it?

[John Rumm]

Why not just control the fan from a humidistat?

[Clive Backham]

out. (But I'd still be interested if anyone can shed some light on the shower pump circuitry).

[Ben Willcox]

Surely the supply to the pump is only live when the pump is running - can't you just connect there?

Ben.

[Doctor Drivel]

Fit a shower light/extractor fan over the shower with a fan override. Available from B&Q, Wickes etc. When you have a shower the light is on. Can be operated via pull chord or on the main bathroom light switch.

[John Rumm]

Install a flow switch in the water pipe from the pump then. Use it with a fan designed to be controlled via a light switch that has an overrun timer. Better still "wire or" it with the humidistat. So the pump turning on starts the fan, the humidistat keeps it going long enough after to dry the room.

I did a ducted fan combined with a shower light, that worked on a remote humidistat. Worked nicely. Gave you a light over the shower, steam extraction from the source, low noise, and automated operation that controlled the humidity.

[John Rumm]

The supply to these pumps is usually permanent, operation being controlled from an internal flow switch.

Personally I would steer away from doing anything that required internal tinkering with the pump, since you will potentially have problems should you ever have to replace it later; especially if with a different model or version.

[Dave Plowman (News)]

You'd need to find the output side of the flow switch. However, tampering with this wiring would rightfully void the warranty - the switch might well not have any spare capacity for extra load. Also if I really wanted to do this and wasn't concerned about the warrenty I'd use a relay or even a second flow sensor.

[Clive Backham]

Thanks to everyone for their suggestions. I'll have a rethink about how to go about this.

[Doctor Drivel]

If you really want this idea fit a flow switch in the hot water supply to the shower. About £25 from Farnell.