Hot water issues

[navyelgin]

I have an Ideal ISAR boiler. recently the temp of the hot water has been fluctuating from normal not water to lukewarm/cold at random times of the day. There are no error codes being displayed althought the t symbol has started to come on. I believe this shows that the plate is being heated to optimise hot water usage, however when this is in the radiators come on, yet the central heating is stillindicating as being off. Has anyone seen this before or heard of anything like it? Please help.

 

[aggis]

You need a change over valve cartridge/service kit, it's passing.Get a Gas Safe engineer to look at it, give the full model details for ordering the part.