Thetford protection.

I took the caravan (Lunar Lexon 640EW) to storage two winter ago (2010/2011) and duly drained all of the systems including the flush water in the loo. On recommissioning in the spring, I found that the plunger pressure had dis-appeared. Having taken it apart I found that the bottom of the hand pump had split and broken away. I repaired this by turning it a few degree and filing a slot to retain the tooth clip on the side. I later visited a caravan spares place a saw that these plunger units were on sale at about £34.00. I didn't buy one as mine was still working alright after the repair. But it did seem peculiar that these were abundant as a spare. This year, after draining down (2011/2012) I removed the plunger to find it hadn't drained fully. I believe that last years culprit was ice in the undrained residue. This year I put a 1/4 litre of anti freeze in the unit and pumped it through. It doesn't affect rubber or plastic and is non corrosive. It may save someone a quid or two by learning from my mistake.