Well, I've now entered the 20th century!!
After 25 years of having a back boiler and immersion heater, we've had it taken out and had a condensating combi boiler fitted!
Wow! No more having to wait for the water to warm up - it's instant! Plus the central heating gets hot quicker - me and SWMBO are sat in just our underpants sweating!!
Took them 1½ days to do the job and very little mess, it's a Worcester Bosch boiler and, as he's an accredited installer, we get 8 years warranty!
Happy chap