Ideal Isar HE24 Boiler

[benkbonk]

Hi, I have an Ideal Isar HE24 Boiler. I had a problem with the Diverter Valve sticking a short time ago, sorted that by removing and using release oil to get it free. That now seems to be working alright.
I have now got a problem with the Boiler running without the burner, C showing on display, this is during the night with heating switched off and also during the day when system upto temperature. System is fitted with two Honeywell motorised valves, one for main central heating and one for underfloor heating, these seem to be working ok. I know Boiler operates from time to time with t display but this is different. Hope someone out there can offer some advice.

 

[crashndie]

what coulor box is round the pcb ?

 

[benkbonk]

The PCB cover is Black.

 

[shambolic]

you say there is no C in display!! Is there anithing in the display like a d or a t??
This would mean dripping tap or domestic leak or cartridge sticking and leaking into ch so cooling down plate hex making it come on to heat plate and so on thus heating rads up

 

[benkbonk]

Sorry if it was not clear but "C" is showing in display. Could it be that there is a problem with the "t" function?

 

[shambolic]

If C is in display then the external controls are calling for heat!!
If the clock and or room stats are in off position then you have a faulty microswitch on one of your zone valves.
Do a search on here for "faulty 2 port valves" or "ch stuck on"
This should sort you out

 

[shambolic]

Also with the C is the blue light flashinf? This means the boiler is up to temp and is still receiving a call for heating.
If the C is in the display with no blue light then the pump overrun is in operation(6 minutes) before returning to 0

 

[Garfeild]

Have you got a frost stat anywhere?

 

[benkbonk]

I do have a frost stat and a pipe stat.
When room stat is up to temperature and valve closed "C" is on display no blue light flashing, pump is running. If I run domestic hot water display changes to "t" and after a short time changes to "d" when water is turned off boiler continues to run for a short time and then switches off. Display is "O". Do you still think it could be micro-switch?