Mixer shower.pump.store tank pressure issue

[mattsure]

I'll try and keep this as short as can.
Friend just moved into new house.previously had new bathroom although only contains mira atom erd bar mixer and wash basin.
Conventional system as in tank and cylinder but has salamander single feed pump fitted ct55+ (one in one out) .
Trouble lies with shower operation - my understanding is that pump needs to sense flow rate through shower to activate. Very poor flow through hot on shower when high up in riser rail . If I drop down to half height will activate and kick pump in ( fed from loft above). Hot basin tap is only 4 litres min.hot sink is 6 litre min .so this is quite poor also.
Ultimately my solution I think will be to raise cold store tank higher. At present store tank 19" 26" 19". Not massive, is sat on loft floor ( key I think) . 28mm feed down to cylinder, 22mm vent. I've replaced gate valve allowing feed into cylinder. I've removed pipework off cylinder and then had attachments to bucket with good to high flow rate to bucket.
Shower feed comes off tee and first down to pump then up to loft across loft floor down to shower. Only shower is on pump. Vent seems blockage free.
Sorry for long post. Probably missed a few details also.
Anyone else with opinion?

 

[dilalio]

Raise tank
or
repipe through floor
or
fit neg head pump.

Or just live with lowering wand to get flow switch in pump activated, then raise wand back to desired position!

 

[mattsure]

Thanks. Looked into negative pumps today but more than likely most cost effective to raise tank I think. Looking forward to finishing this job just to sort it out but might be couple of weeks before can get back .