I have just installed a heat pump to my indoor swimming pool however after running fine for the first two months, the breaker has begun to trip at any given time.

The heat pump is a 5.5kw 220volts 25amps which I wired with 4mm three way wiring (neutral, live & earth). I have installed a 20amp 6ka hy mag breaker(orange flip switch) to the mains board of the house.
The way I have explained the installation was given to me by the suppliers of the heat pump & they in turn are lost for words, please help as I am not sure what I did wrong.

Regards

Andredev

So you installed a 20 amp breaker for a 25 amp pump?

Neutral, live and earth for 220V?

andredev didn't favor us with his location, but that is how they do things on the East side of the Atlantic.

I don't have a table for 4 mm wire, but it is larger than our #8, usually good for 40 amps if copper. Check the rating for the 4 mm and type of cable you used. If it is OK, try a heavier breaker.