Shower pump does not start

[MarkSmith]

Hi all,

I have fitted a shower with a pump. Cold tank is in the loft, shower on the floor below. Pump on the floor next to she shower (in a cupboard).

When it works it works well, but most mornings it will not start. Turn the shower on, nothing. To make it start, dangle the shower head down to the floor: water dribbles then flows out, and the pump starts (as it should when there's water flow). You can then switch it off and on at will - all fine. Next day, same problem.

It's like there's not enough of a head to start the water flow - but there is - the water level in the tank is a good meter higher than the shower head, which should be more than enough to get a little flow. And indeed it DOES restart shortly after it's been used.

I suspect something like a sum-of-syphons, perhaps caused by us opening taps throughout the day and reducing pressure in part of the pipework, something like that, but I can't work out exactly how it's happening or how to resolve it.

Any suggestions please?

Many thanks,
Mark

 

[Richard C]

You don’t mention where the HW cylinder is or what sort of take off flange you have? Have you any up & over loops between the pump & the mixer or shower head; they will also affect static head & should be at least 600mm below the base of the CW tank. Relative location of the tank, pump & pipe runs is only indicative, you need a flow rate of 1 lire/min to kick the pressure switches into life, for some reason you aren’t getting it. The pipe runs could be poorly designed/long/restricted or getting air locked; any up & over loops should be vented.