Thank you for responding. There are three dials on the front of the boiler (apart from pressure guage). The first is HW temp. The second has 4 positions (to the left, HW only; pointing up, standby, to the right [2 o'clock], HW and CH [economy], further to right [4 o'clock] HW + CH with water...
In April I moved into a house with a Volkera (Unica 28HE) boiler and an Altech programmable thermostat with RF. (Installed Feb 2009).
Now that it's cold I have tried to turn the CH on (boiler has worked fine for hot water all summer). I had to change the batteries in the thermostat but I have...