Intermittent hot water problem.

[Allie01]

Hi, I wonder if anyone can help me. My flat has a Ferroli DOMicrocondens F24 boiler. The central heating works fine but there is a problem with intermittent hot water. When turning on the tap, the boiler fires up and after a while I get hot water, but only for a second, then it goes freezing cold...then it cycles between hot and cold (mostly cold). The result is a sink or bath full of barely tepid water and a huge gas bill.

Thanks!

Edited to mention, the pressure here is high, so the flow has been turned down and it still happens if the tap is not fully on, or even half way.

 

[45yearsagasman]

Dual pass heat exchanger on these. Could be scale in that or maybe flow switch problem. Impossible to give you a diagnosis without being in front of boiler. Get a repair call booked in.