Glow worm 24cxi problem

[enki]

Hello.

At first time the boiler showed F5 fault which according to manual is related to overheating. The thermostat was reset and everything worked fine for some time. Then boiler overheated again but before I noticed that the temperature on display was showed like 50C degree but radiators were so hot that I couldn't hold hands on them. At the present moment overheat thermostat is burned and ignition is not working so I decided to replace them which will be done tomorrow.

My questions are:

1. What should be normal thermistors resistance (flow and return) and domestic hot water thermistor in about 17C (my readings of first ones are about 10KOhms and 11KOhms)?

2. The overheat thermostat is unplugged but there is no F5 fault which usually occurs (I don't know how is it related to ignition unit) so is it normal that this fault is not showed when ignition doesn't work?

3. Is the wrong temperature displayed more likely because of broken thermistors or problem with PCB?

Thank you for every advice.

Greetings.

 

[Agile]

before measuring the thermistors you need to let the boiler cool down for about two hours.

Most boiler thermistors are about 10k-13k at room temperature.

Either the thermistor or the PCB could give the wrong reading.

But you have not mentioned the boiler's temperature control knobs. What happens when you lower them to minimum?

Tony

 

[enki]

If central heating knob is set to minimum (I think it is about 40C) the heater works but it is not stable (overheating sometimes) and radiators are much more hot than that. The running water know doesn't change a thing, whatever minimum or maximum water is nearly boiling causing overheat thermostat to switch off.