raven heat csi 120 hot water cycling on and off

[hollow]

the house we moved into has this boiler already installed with the instructions etc left with it ,
i had to remove a radiator from the wall so the plasterer could get behind

this obviously dropped the pressure on the boiler ,so i refilled the boiler upto 1 bar , since this about a week ago the boiler has been acting up

every time you use the hot water the boiler fires up but when the water heats up it shuts the gas burner down till the temp drops ,then restarts the burner ,causing colds spots in the water which obviously hinder filling the bath etc .

the boiler seems to have stopped modulating the hot water temp , no fault codes except before refilling the boiler (not from empty just topped up ) when i removed the radiator , which was code 04 Failed overheat

but that code is for the heating not the dhw and the heating is fine

 

[gas4you]

At best you could have somehow created an air lock in the plate HE, but this is extremely unlikely.

It sounds more like some crud has moved and got in the system side of the plate HE so the boiler is getting up to temp and the plate is not transferring the heat across.

Could also just be coincidence and the ch thermistor needs replacing

 

[hollow]

worse case scenario ??

the thermister part is cheap i could buy it and get the gasman to install it thus saving on the markup price , but what if crud is in the heat exchanger is this a new part or can it be flushed out ??


saying this as a precaution i had the system cleaned drained and refilled with fernox only around 6 months ago

when the radiator was removed the water ran clear