My hot water gets hot then cold then hot then cold and so on.
To get a bath full of hot water we have to run the tap very slowly.
Having a shower is out of the question at the moment. (shower comes
from hot and cold taps)

I have taken out the secondary heat exchanger and cleaned that. It was
not very dirty.

What would be the order of looking for next to cure this problem?

I am guessing, flow switch then perhaps diverter valve?

Is there a way to test these before I go to the expense of replacing
them?

All suggestions gratefully received.



Steve...