Boiler not firing up

LaurenB87

So got my new thermostat and extension kit today and all has been installed (old thermostat was wireless and kept existing backplate/wiring from old receiver for the extension kit)

Everything is connected but the boiler isnt firing up when i increase the temperature.

Any ideas?

Thanks!

LaurenB87

Old thermostat is a drayton digistat +3 rf

Combi boiler and as far as i'm aware its pumped. Hot water works ok just the heating side of it