I hate showers and never get involved with them,electric,gravity,pumped,thermostatic,mixer,concealed,shower trays,wastes,doors,all a pain in the f*****g arse,just glad there's keen plumbers like you,thank you
Shower feeds are decaicted supply's, cws and separate feed off hot tank.Reading your OP again, the behaivour of - When it runs fine, turn off pump and it continues to flow fine under gravity but then leave it for a while and then it's back to a trickle suggests air is being introduced into the feeds over time. Are the feeds dedicated to the pump? Is the hot flanged? That coupled with pipework going into negative head areas will all exacerbate that effect. If it isn't a LP shower too then the flow through the check valves and cartridges slows it beyond activation, that's clear by the trickle out of the shower head. Does flow increase at all if you drop the shower head?
Realistically the fixes are, remove the check valves and see if it flows enough, could try air vents but ideally you would want to fix the feeds if air is an issue IMO, could fit a manual activation switch and finally most expensive is to change the pump to universal.
Ermm... No about a meter and a bit at a guess.Your shower requires minimum 0.2 bar to operate it, do you have 2 metres between the shower head and the bottom of the cold water tank/cistern/container ?
No not yet, the cover plate has been siliconed on and will be difficult to remove. But an option I will have to try.Have you removed the non return valves they will be located in the inlet fittings or in the inlets of the shower valve if you haven't removed them you have got no chance of it working.
Stuart turner I think.What pump are you using and what type of HW cyld flange?
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