How to get the water to heat up?

The heating is totally separate from the circuit that produces hot water. Ferroli only have the new Optimax range that has a diverter valve, so ignore the previous answer if the boiler is quite old. Depending on the model it does sound like the flow meter at fault on the hot water side. If pressure is fluctuating on the heating side and the pressure gauge is moving up and down it could be a problem with the expansion vessel. Both faults can be fixed by a trained installer relatively cheaply.

John B
October 2008

sounds like the micro switch on your diverter valve when you put your hot water tap on ther should be a clicking noise within 10 to 20 seconds if you do,nt hear this then it is not switching over an more likely to be microswitch or debris on the diaphram

rob gallagher
October 2008