Mr builder (The usual way is to raise the present cylinder.) fraid not, it all depends on how high you can get the stored water tank, the bigger more area the better more weight you see, the hot water out the top of the cyl is equal to the cold into the bottom of the cyl,CC1 you need to investigate if you can get the storage tank into the higher loft or two tanks for more water then, you could have a pump installed with shower as well,the other very expensive option would be to get a mains pressured cylinder,have you tried to put temperature up on the immersion or cyl stat,if boiler heated, not recommended though if you have children HTH Tez