My sanivite pump does the same thing, not emptying the bath unless it has been 'activated' by a sink full of water from a higher level.
I'm sure in my case that because the bath waste enters via a bottom pipe, and the bath is at a low level like your shower,there is probably silt built up in the pipe because they are horizontal and the silt doesn't get washed out by gravity or fast moving water, and maybe silt/grease in the bottom of the pump, and the water from the bath has not enough 'fall' coupled with this long length of horizontal pipe.The water does not rush into the pump to activate it.
I am considering disconnecting and cleaning all the pipes, and would like to know how to get the lid off the pump to clean out the pump.
It is 6 years old and works well.
But I've also thought that it would be a good idea to have a separate pump, near the bath so there will be very short pipe work, and it will then be mostly sloping downwards and not much horizontal.
I also wonder if ideally, the pump should be sited nearest to the lowest appliance that feeds into it, so that the longer runs of pipe are always conming from a higher level and do not silt up or have water sitting still in them. but this would mean running long lengths of sloping pipe through one room or another, not nice!
Julia, September 2008
