On Nov 20, 3:41*pm, Oren wrote:
On Tue, 20 Nov 2012 16:47:58 +0000, diydave123

wrote:

I've just had a new Vaillant EcoTec 831 boiler fitted with a Salus St620
Programmable Thermostat. *Read the instructions, programmed it as
described to come on for an hour in the morning and a couple of hours in
the evening - tootled off to bed. *Woke up at 1am with the boiler
cranking out heat like something possessed. *Re programmed it, using 24
hour clock - same thing. *Can't understand it. *The instructions are
simple enough. *There's nothing obvious that's wrong.

Thanks for sharing!

Seems like a lot of information is missing. When
the system was cranking out heat like
something possessed, what temp did the thermostat show
that it was trying to maintain? If it said 90, then it's likely
a programming problem or far less likely, something wrong
with thermostat. If it showed 60, then there is a more
serious problem with the boiler not responding to the
thermostat.