I have just moved into a home with this heater I have done all it says setting and resetting using the timer ect making sure tht the clock is the right time but my heating wont go off just when I thought I had mastere it the heating came on at a different time to what I had set it for any ideas???

Dawn, April 2013

We have also just moved from GMT to BST - does your Timer programmer know this?

Are you running a timed programme for Domestic hot (Tap) Water? If so that might be confusing things.

As mm says - some systems - especially where the boiler is in an exposed place - have a Frost Stat set to come on a few degrees above freezing to protect the pipes.

The Normal conditions to fire up a boiler for central heating are a combination of Timer AND Room Thermostat. A Frost Stat is wired separately and will override the timer.

To test things - turn the Room stat to its lowest setting and set the timer to off - if the boiler still fires then it will be the Frost Stat.

But wait for the weather to get warmer first...

Peccavi, April 2013

could be a room stat overiding the timer or a frost stat doing the same

mm, April 2013