On Sun, 19 Nov 2017 13:44:55 +0000, Andy Burns wrote:

They can but not always. I can't help feeling they would help
themselves if they ran the fan at low speed to increase airflow, even
when there wasn't a mains problem.

My little one doesn't come with a fan. I hi-jacked the SNMP(?) card
slot space and fitted a PC slot exhaust fan along with a speed
controller.
As noted above, mine has a fan, but only uses it when it's covering a
mains problem. Quite annoyingly it runs it for the daily spikes of a
couple of seconds around midnight when "something" at the substation
adjusts for over-voltage.

Complain to your DNO. Ours (Electricity North West) takes complaints
about the supply quite seriously, especially if you have data to back
up the complaint. A regulator shouldn't spike as it changes and
"around midnight" (*) strikes me as a bit odd as well. I wouldn't
expect load variation to be that consistent, weekday/weekend being
different at the very least.

(*) 2359 +/- 20 mins?

--
Cheers
Dave.