LOW HOT WATER PRESSURE, BUT SWITCH RESOLVES THE PROBLEM?

Have very low hot water pressure, takes an age to warm up and can only use one hot water tap in the house at a time. System is 6 years old in a hard water area. However, if I use the switch facility it solves all the problems, but the manual says only to use in an emergency??? Have called local plumber in who couldn't trace the fault and have checked the expansion tank is adequatley filled.

Weird. Are you saying the low water pressure is sorted out by using the 'Switch' backup? I cannot imagine how this would make any difference.

If the flow rate from the hot taps is much lower than the cold taps then this is a water scale problem. The heat exchanger needs changing. THIS will fix all the problems!

Cheers, Mike