Last week whilst on holiday the hot water supply in the caravan was very spasmodic with spluttering, eventually the water ran ok, I assume that air was causing this. I changed the non-return valve and the o rings. I though at first that I had sorted the problem but no, stil the same problem. Any suggestions out there to what could be the cause of this? The water system is the basic push in Whale pump. As I left the site, haveing unplugged the system water was dripping out from the the blue plastic inlet - and still is now we are home. Thanks Tony