Actually Seadog, I havent tried that! the problem, I am pretty sure, is that we have a very marginal head, as if you switch the shower over to the hand spray, and slowly lower the hand spray, the pump starts at about halfway between the shower head and the tray. BUT, on one of the showers, and one of the sinks (Not in the same ensuite, which we suspect is also fed by the pump), the hot water flow stops entirely after a few moments, but the pump does not start, so we think there is still an airlock somewhere, but I will know more when I go back monday. We can get the pump running, then turn on the taps and hopefully push the airlock out. This is not an old installation, or pump, but we doubt it has ever worked properly. Add to that the plumbing for the showers is in the loft, but the plumbing for the sinks is under the floor, then you begin to see what a mess this is, but we will get to the bottom of it. So far I have cleaned all the filters in the pump, checked the flow to the pump, which is 22mm pipe, and good, and topped up the air in the pressure vessel on the pump. it seems to be the plumbing beyond the pump which is restricting the flow sufficiently just enough to make the shower pump fail to switch on reliably. Thanks for the comments!
Phil
East Yorkshire