My hot water is working fine, boiler fires up OK.
The problem is that my heating won't switch on.
I have a wireless thermostat which appears to send and receive the correct signal as the receiver switches on and off when I change temp of the sender and I get all the right lights.
Every now and then I can get it to come on but I have to turn temp up and down until it switches in - sometimes I have to do this for an hour or more.
I have an Ideal/Icos boiler (not combi) about 8 years old.
Any suggestions please.