I have a hot water and central heating boiler which for the hot water only fires up when I turn on the hot water tap. My boiler fires up and provides hot water - but then it turns itself off again so the hot water becomes cold - then the boiler comes on again and the water becomes hot again. This is not so much of a problem with the sink supply but it is making showering an interesting event! Is there something wrong with the boiler or is this a standard feature of the boiler type? The boiler is made by Ferroli and is a Modena 80E model.

Gospen, June 2011

if you see the burners go off when shower on and it goes cold likely a hw sensor fault .if burners stay on and the shower goes cold possible shower fault .see if you if you can get same fault if you leave the basin tap on slower ,if yes then it is the boiler

ex ferroli engineer, July 2011

I had exactly the same problem with my Vokera boiler. I phoned Vokera and they said that as the water temperature at the boiler is a lot greater than at the shower the boiler may try to compensate by switching on and off. They said to turn the hot water temperature (not central heating) down to 50 degrees. I did this and it has solved the problem; the shower temperature now remains constant.

Ablitim, June 2011

there is a good chance the heat exchanger is blocked up.You can remove and clean them or replace.will require system drain down to some degree and strip out inside boiler

A1, June 2011