I have a gas central heating system. The main boiler system consists of two
tanks one on top of the other. The top one beng hot water and actually open
at the top. I don't know how old it is because it was here when I moved in.

The system has not been used at all for some months. I don't use it to heat
hot water as I do this independently when I need it.

Switching on the system tonight I find that the pump activates but the
bottom tank does not heat up. I think there is no gas flame ignition. The
pump also seems noisier than it should. but that is difficult to judge.

Before I call somone out to look at it can anyone diagnose what may be the
problem and what if anything I can do?