Some advice please as I can not understand what I have done wrong.
I have replaced our shower suite.
Originally I had a bath with shower over which was a wall hung pumped unit gravity fed.
I have removed the bath and built a purpose shower enclosure instead.
Fitted a Salamander RSP50 pump, situated a lot closer to the floor (about 16 inches above behind a false wall. And installed a Triton Capella mixer unit with drench shower and hand held shower.
However. the pump often fails to come on unless the hand unit is put on the floor. Which suggests negative head. And when it does come on it gets slower after a minute or so and sounds like it is struggling to draw water. Swicth off and on and it's Ok for a minute or two again. If you switch it to the overhead drench head it is useless.
what's baffling me is that the new pump is more powerful and is lower than what was orginally there. And the pipe runs are now shorter than before. So why the negative head issue. I wish I'd stuck with the ugly wall mounted pump now.