HI Folks

Our domestic central heating is run by a ground-source water heatpump -
most of the time this is very successful, it was installed about 12
years ago.

In the last 24 hours, the MCB that feeds the heatpump circuit has been
tripping out. When it's manually reset, the heatpump fires up again and
runs.. until it trips out again.

Wiring is as follows
Main CU has a D40 MCB that feeds a smaller CU in the workshop, where the
heatpump is housed. A D20 MCB in this smaller CU feeds the heatpump -
which is nominally 3kw, but takes a big switch-on current.

As I say, this has all worked well for the past 12 years - until last night.

So - do MCBs age over time? Am I seeing an MCB failure, rather than a
heatpump failure?


I have a call into the local engineers anyway - but just wondering...
I'd rather replace an MCB than a heatpump!

Thanks
Adrian