Hi , do you mean it trips the power or is overheating?
The indicated temperature rises steadily to about 5C below the set point. Power decreases and temperature reduces slightly before a surge of heating occurs. This causes the temperature to exceed the set temperature and the heating trips out. This system cools to about 45C (with radiator symbol flashing) and then restarts and repeats the cycle
Hi , is the pump wired directly into the boiler, for the pump over run to kick in? In the boiler wiring the pump should be wired directly
Hi , you may have a fault with one of the temperature the temperature stats .either the flow or return. Best to change both at the same time
No , I don't think so the boilers have modulating gas valves that start low before going to high
Why are you convinced that it is a PCB or gas control problem?
Are you speaking from experience?
No I have no experience of gas control systems but if the gas valve is controlled to initially deliver low power and then switches to a higher power it seems reasonable to ask what causes that change of mode.
I also understand that the controller is a proportional controller in which case you would expect a high power input when the difference between operating and set-point temperatures is large and this should decrease as set-point is approached. In my case there seems to be a surge in power as the set point is approached. There just seem to be a whole ot of illogical actions.
Sorry , I am just a simple boiler engineer, working to diagnose boiler faults . will opt out to see if you can get an electronics engineer who can explain all your need to know .
As I originally told you , you may have a fault with your temp thermistors. These are variable with temperature change and control when and how the boiler fires up
Hi , could you please rate your answer , thanks
Your advice is proving helpful thank you.
I have tried to click on a smiley face but get no response. Do you need to sign off to say you have finished this enquiry?
Hi , I'm not too sure will check with cust services ,all the best