Giff wrote:

I've just replaced the timing unit for my Vaillant combi boiler as its
never worked properly since I moved in. What I expected to happen is
that when the timer is set to ON, the heating/hot water will come on
(providing its selected on the boiler itself), when the timer is set
to OFF, only the hot water will be available.
Unfortunately, this isn't the case. It looks like the zone valve isn't
working in the boiler. (I've checked and made sure that the timer
works correctly).I do know that when the Vaillant engineer came to
look at it prior to me moving in, he couldn't get the timer working
and therefore "wired it direct" whatever that means.
I assumed that this meant he'd bypassed the timer although now I
suspect he also bypassed this within the boiler.

Does anyone know how I get round this? Is it safe for me to go delving
around inside the boiler itself?

1) You don't happen to have a wall mounted thermostat anywhere?

2) All vaillants require a connection between terminals 3 and 4 to run
the heating.
This applies to Sines, VCWs, & Turbomaxs.

It's mains powered electrical appliance no more dangerous (less
actually) to delve into (electrically) than a toaster.


--
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