stubuzz

It automatically regenerates when it gets to about 45% full, but regular long trips/motorway driving will help keep it empty and prolong the life on the dpf and cat.

Is the builder local? If so, he should of known about the soil conditions. Talk to a structural engineer and call another builder.

The breaker protects the wire. Changing it will not make the heater any better or any worse. Change the wire or use a lower wattage heater. How long is the wire run from the consumer unit to the heater?