On 03/02/2020 08:24, Adrian Brentnall wrote:
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'ts a lot cheaper to replace to see...
Can we confirm this is not in fact an RCBO and earth leakage is not
involved?

MCBS can age. But 12 years is not long...



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

Thanks
Adrian



--
Religion is regarded by the common people as true, by the wise as
foolish, and by the rulers as useful.

(Seneca the Younger, 65 AD)