In message .com,
Martin Pentreath writes
The service manual does indeed say "the boiler must be drained of all
water", but that's all it says, it doesn't say how to do that.

.... Because not every boiler is installed in an identical fashion

There should be valves to isolate the boiler, then you have to use a bit
of grey matter to find where best to break the circuit


I wasn't
sure whether this means draining the rad circuit as well, but from what
you're saying it doesn't. There's no obvious draining point underneath
the boiler. Any advice on the usual procedure for draining just the
boiler would be very welcome.


--
geoff