Ideal Isar HE24

[crad2]

Can anyone advise please. Hot water problem. Diverter valve changed (was sticking) together with hot water thermistor. When hot water is drawn, boiler shows d and burner light comes on, water temp is ok for a few seconds then not great and after about a minute burner light goes off. Fan seems to be varying speed slightly (sounds like it). CH is fine. Thank you in advance.

 

[kidgreen61]

I'd be looking at plate hex blocked

 

[crad2]

Just noticed that when boiler switches between hot water to CH there seems to be a lot of air trapped in the boiler making a noise. The system was drained to replace the Diverter valve then refilled but I wonder if the automatic air vent is stuck not allowing the air to escape.

 

[Johntheo5]

Just noticed that when boiler switches between hot water to CH there seems to be a lot of air trapped in the boiler making a noise. The system was drained to replace the Diverter valve then refilled but I wonder if the automatic air vent is stuck not allowing the air to escape.

Is the boiler pressure a minimum of 1.0bar?. If the DHW flowrate (even if cold) is > 3.0LPM then unlikely to be a blocked plate hex except its blocked on the primary side. if the hex is blocked then one might expect the water to run very hot then cold. If the DHW temperature is adjustable, suggest increasing it to ~ 60C.