Question

Hi Tom. I've got a crystal compact mk2 water socket/pump fitted to my 2001 caravan and I'm having some connection problems. It'll work intermittently, then I'll have to give it a little wiggle and it'll start again. Also sometimes the pump will be running even though there are no taps on. I notice that it is obsolete, so if I need to change it what is the alternative part. Many thanks :-)

Answer

There are generally two types of water systems used in caravans. The first is the microswitch system where each tap is fitted with a microswitch. When the tap is opened the switch is turned 'on' and power is supplied to the water pump. This pump is normally a submersible pump that drops into an external water container. When you close the water tap then the switch is turned 'off' and the pump will stop. If the pump continues to run then there is a fault with the microswitch which normally means that it will need replacing. The switches in the taps are wired in parallel so that whichever tap you turn on, power will be supplied to the pump.
The second system is the pressure switch system. With this arrangement you have a pressure switch in the water system which senses the water pressure. When you open a tap the pressure in the system will drop, and this drop in pressure on a diaphragm in the pressure switch causes movement of the diaphragm. This movement has the affect of turning the switch 'on' and thus supplying power to the water pump. Conversely when you turn the tap off the pump will continue running for a few seconds which has the effect of building up pressure in the system. This increase in pressure again causes movement of the diaphragm in the pressure switch which has the affect of turning the switch 'off' and thus stopping the pump. If the pump continues to operate after the tap has been turned off then it may simply be due to the pressure switch needing adjustment or there may be a fault with the pressure switch where a component or the whole assembly may need replacing.
With pumps such as the Shurflo or Flojet the pressure switch is part of the pump itself. On some systems where the Crystal 2 water inlet is used the Whale pressure switch, our ref 105500, is installed in the cold water pipe work, normally under a seat and close to the water inlet. On the Whale Watermaster system the pressure switch forms part of the water inlet and an adjustment screw can be found on the rear of the inlet.
The Crystal 2 water inlet has now been superseded by the Ultraflow inlet and a conversion kit is available, our ref. 135667.