I have a Brittony 80 combi boiler made by Chaffoteaux, which I
installed about ten years ago. Almost every year the heat exchanger
gets partially blocked, resulting in fluctuating temperature of the
domestic hot tap water. I live in a very hard water area.

So a year ago, when I last renewed the heat exchanger, I also
installed a phosphate doser on the water mains inlet pipe to hopefuly
reduce limescale.

However, now, a year later, the heat exchanger seems to be playing up
just the same as befo hot tap water coming out luke warm, then
slightly warmer, but never really hot.

Is this the heat exchanger blocking up again, or could it be something
else?

I can buy yet another heat exchanger tomorrow, but is ther anything
else I should be doing to prolong its life? Water filter, perhaps?

Does anyone know where the filters (if any) are located in a Britony
combi? I can't find any reference to them in the manual, but see to
recall a plumber talking about them once. How often should they be
cleaned?

Thank you,

Jim D