Phillip Brown wrote:
"BigWallop" wrote in message
k...

"Phillip Brown" wrote in message
.uk...

"Toby Sleigh" wrote in message
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snipped

Toby

Must be a special 'break around Christmas time' setting they all have.

My fan isn't turning however, which indicates to me that the PCB is the
2nd
in line, fan being 1st in line. I.e. if the fan doesn't turn, then the
PCB
can't be the fault?


How did you test the fan, Philip? Did you actually remove the fan to do
the
testing?


Simpler than that, I can't hear it. Normally it hums quite audibly. I'm
pretty sure it's the fan that hums anyway, and now no noise from it.

(You have checked that the fan's not just jammed by something, haven't you?)


However tomorrow I will buy a neon screwdriver and test for 230v across the
fan coil. Can people here confirm that is correct and safe?

Yup, that'll give you a reasonable indication. Make sure you know how to
hold it to get it to light up: there's a little contact on the part of
the screwdriver you hold which you have to be touching for it to light
up when the tip of the 'driver contacts mains (I know this sounds like
an apprentice booby trap but it's not: the current required to make the
neon light up has to go travel through your body to earth, but it's so
minute you can rarely even feel a tingle from it). Check it on parts of
the system you know should be live e.g. the thermostat and programmer,
then check the live terminal where the supply cable enters the boiler.
Check also that the neutral terminal is _not_ live (in case the
connection has come adrift on that side).

WRT Lurch's comment on neon testers and multimeters, note that both
neons and modern digital multimeters have such high input impedances
that they will give unreliable indications on some sorts of faults e.g.
where a connection is basically broken but still capable of passing or
picking up the minute amount of current required to light a neon or
register on a meter. For these situations a simple 2-probe mains tester
with LEDs (or as a DIY alternative a low power mains bulb such as a
fridge or oven bulb or small candle bulb connected to 2 probes) will
give a more reliable indication.