Sink
Tap Switch Upgrade
Each time you
lift the sink tap lever, a small micro-switch in the tap body operates
and controls the 12 volt power to the pump motor in the water bottle
under the sink.
The micro-switch
contacts carry the entire current load and each time the switch
opens or closes a small amount of electrical arcing happens, which
will eventually cause the switch to fail. Although it is possible
to dismantle the tap assembly and clean the contacts, it is a difficult
and intricate task. Success is frequently short-lived and a new
tap body costs around £30.
By incorporating
a heavy duty relay into the circuit, the tap micro-switch can be
relegated to the task of energizing the relay coil which only requires
50 or so milliAmps and will now last for ever. The current driving
the pump is now carried by the relay, with contacts rated at 5 amps
and designed for 100,000+ operations, and costs less than £3.
The relay Roger
used is a miniature Double Pole Double Throw, but since only one
pair of contacts is used you could buy the cheaper Single Pole model.
Apart from soldering
the connecting wires to the relay, the remainder of the connections
to the caravan wiring loom are made with either conventional screwed
connectors; or push-fit joiners soldered or crimped to the wires.
Roger has provided
a circuit
diagram, showing the before and after wiring layouts, and an
image of the relay
strapped to the waste pipe.
This project
does not (yet) include a step by step guide to the fitting and wiring
process, so a degree of electrical knowledge is required, but is
a very valuable idea for Eriba vans 5 or more years old. |
