Ideal Isar M30100 - heating on but not firing

Not sure if anyone can advise? We have had the boiler for approx 5 years. Yesterday when we arrived home from work the house was like an oven - the heating rads were all on but room thermostat off and boiler not firing, showing "0" as standby.

Have had to switch all rads off by their thermostats (lucky we had them fitted lol) and boiler appears to fire up ok when turning on/up the thermostats ie "c".

Hot water boiler shows "d" as it should, fires up and water gets warm but doesn't get very hot.

Have had a look at the forum and it sounds as though it could be servo valve, hot water microswitch, faulty tap water flow switch or DHW stat (if not the same thing).

I wondered if someone can pinpoint what problem is as I don't want to pay for something to be replaced which needn't be - we don't know any recommended repairers so have learned from experience that you can't trust everyone.

Many thanks for any advice.

so do the rads heat up when the hot water is ran for an extended period, ie to fill a bath??

Could be your divertor valve whisch is a very common problem.

Get a on off repair by British Gas, £170 for the part and labour.

Not sure about that one - we have showers so will have to give it a go to find out. Many thanks.

As said the divertor valve, very common fault on these.

gas4you said:

As said the divertor valve, very common fault on these.

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int everythin on the m30100 model!

Had lots of these Ideal diverter actuators jamming , i.e motor spinning in actuator but not moving spindle so boiler thinks its on hot water , tries to keep the preheat temp up but ends up heating the whole heating up to 80 degrees!!.......... Isar, Icos ,Istor etc etc.......crap crap crap