Thanks for you help. I've wired it all up and the heating is now switched by
the timer.

The only strange thing I've found is that when I switch the heating on with
the timer, I can hear the boiler fire up and you can see it light. When I
switch it off, the heating switches off but the boiler is still making a
noise. Sounds like a fan but the fan isn't on. If I switch the heating off
using the switch on the boiler then the noise goes likewise if I turn the
hot tap on and then switch it off, the noise goes.

I know I didn't add this earlier but is Vaillant is a Turbomax if thats any
help.

Anyone out there know what the problem might be?

Andy

"Ed Sirett" wrote in message
...
Giff wrote:

Ed Sirett wrote in message
...


Generally there is LN&E and another three terminals marked 3,4&5.
Heating 'go' is done by connecting the mains on terminal 3 to terminal
4, terminal 5 is an extra neutral for devices that need it.

External timers go in series with the thermostat.

Just opened it up. Looks like the guy who came to fix it actually
disconnected the wires from the timer that would control the on/off
heating. What he's done is put a loop between pins 3 and 4. I assume I
could remove that loop, add the L from the heating control into 4, the
N into the same mains N connection. This should mean that the power to
the heating should only come on when the switch is made on the timer.
Is this right? I know I'm probably asking some daft questions but I'm
a bit of a first timer at boilers.
Thanks for your help

The 3,4 link should mean the boiler runs the heating all the while (when
the summer/winter switch is put to

This is very basic electrics really: if 3 is connected to 4 the boiler
runs the heating.
You might well find that simply connected the mains to 4 will also do
the same, but is best avoided since you might get odd effects.
If you want thermostat as well you will take the switched output from
the timer and connect to terminal 4 via the thermostat.

The timer should get its power from the L&N direct from the mains and it
should conect 3&4 togther to make the heating run.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html