Hello! Please can someone help me out with this problem. I have a
Vokera Excell 80E boiler which works fine most of the time. The
problem is that when I have a shower it will overheat and lock out
meaning I have no hot water. It eventually resets itself and starts
working again

This problem occurs most times that I use the shower. Sometimes I can
be in the shower for 10 minutes and it will be fine, other times it
will overheat after a few minutes.

It happens regardless of whether the central heating is on or off at
the time. The amount of time it takes to overheat varies but I'm sure
if I ran my shower long enough it would overheat every time. I always
check the pressure of the system and it is always between 1 and 2 bar.
The boiler has a temperature gauge on the front but this doesn't seem
to work. The water temperature is not set very high so I do not think
that is the problem. The boiler has never overheated due to the
central heating being on, only hot water when I'm in the shower.

Any ideas?