Ferroli Domicompact F30b

[JE-P&H]

Any advice on this problem would be appreciated!

Ferroli Domicompact F30b Combi Boiler that if the customer has the heating on, but then runs a bath the radiators get ridiculously hot. It has a dual heat exchanger so no DV which rules out any crossover there. So I'm thinking there must be a problem with the Secondary heat exchanger but not entirely sure what it may be System Pressure rises to 2 bar when fault occurs but falls once HW stopped, so not water getting in from HW side. Any help would be appreciated?

 

[gasmanrob]

is it just whilst the hot water is running or for a while after??

could be that after the hot water demand the flow switch is sticking or sending a signal and the boiler isnt modulating down.

or could be the pump is running during hot water demand and the high fire rate is also being sent round the heating circuit.

or the velocity at which the water is travelling at carrys a great momentum and even though the pump has stopped the water is carrying this momentum on and drawing heat from the heat exchanger

or....... its because its a ferroli and these things were sent to try us

 

[JE-P&H]

thanks for the reply, I haven't actually been there when the fault happens trying to narrow it down, when I was there I tested all the calibration on the HW sensor and Flow Sensor both fine. Its definitely been sent to try me! Turning the heating off stops it but that hasn't really helped me narrow it down!