Ideal Isar HE30 Boiler – H3 fault

Can anyone point me toward a guide on how to fit a DHW thermistor on an ideal HE24? Thanks

Hi
How come that boiler tends to break always during a winter?

I was reading 3 topics on a thermistors in Ideal Isar boilers.

My model is HE30, and it displays H3 fault.

For now I keep Central Heating running as follows.
When H3 occurs I run hot water from tap and then cut the power at socket switch (30seconds) + after powering again I "reset" at the front panel. For now it works with variable success!

Also I have a small leak - probably at the right back of the boiler looking from front (didn't remove cover to check). It drips from time to time.

From all informations I was reading it suggested that the problem should be
- thermistor
- PCB
- return valve
- dripping water
- mucky heat exchanger
- wiring loom
- dripping water

The call out charge is 260 + heat exchange 160 if required.

I would really appreciate if someone could advise me on
- why wiring loom and/or dripping water could trigger H3
- is thermistor attached to anything that when loose or removed can release poisonus carbon monoxide?

I'm still in the process of reading. And wouldn't bother to fix myself if PCB or HEx is broken.

But would appreciate any help with the other causes !!!

H3 is the thermistor or water on the electrics to it.
Not a gas part.
Your best bet would be fixed price repair from ideal but boiler probable 10-15 years old and depending on the leak and lack of servicing in its life time may be cheaper being replaced.