Fitted a tap shower mixer, cold flow is high but hot water has no pressure when lifted higher than the taps pressure on hot taps in basin is fine, do i need to fit a shower booster pump ? hot water cylinder is situated just next door in cupboard and i beleive is a fortic type and has a a cold water fill connected to the boiler would fitting a booster pump be the answer or make things worse and would it even be possible?

Hi Mike,

Its a problem with fortic tanks ( should actually call them combination tanks as Fortic is only a brand). Basically you need vertical distance ( head) between the cold water storage tank feeding your hot water cylinder and the tap ( or shower head in this instance). Combination tanks are often found in flats where there is no loft, but the lack of elevation between tap and tank always makes them low pressure... as long as there is circa 1 metre plus then the hot should flow ( as the combination tank will be mounted at circa 2 metres height then this is why your bathtap and basin work fine). By fitting an elevated shower hose the hot water will cease to flow once lifted to within circa 1 metre of the cold tank level ( this will vary depending on pipe layout , sizes etc but will be 1 metre approx).
The problem with your pump suggestion is twofold ... first off you have ( by the sounds of it ) mains pressure cold and gravity hot . Pumps cannot be fitted to mains pressure cold but your shower will work best if both hat and cold are at the same pressure ( ie both gravityfed or both pumped. Second problem is that pumped systems require a generous sized cold tank ( suggest 50 gallons min) feeding the hot cylinder ( and gravity cold to shower valve)... without a large tank the pump can run dry and this will cause damage, unfortunately cold water storage in a combination tank is likely tobe only circa 10 gallons.
if you live in a house with loft you could get a tank fitted to the loft and swap your combination tank for a single hot water cylinder. If you live in a flat then this is not an option and you should consider ether an electric shower or a pressurised hot water system ( eg megaflow) or get a combi boiler which will heat the hot under mains pressure.

Good luck