Ideal Istor HE325 No CH when HW is not hot

[Bar19191]

Hi
I have this istor ideal HE325 monster 9 year old. Which was OK up until last week. Now suddenly the Central Heating timer is not kicking in. If I run the hot water for sometime and immediately after that if I set the timer to run Central Heating it works OK.

Wonder why?

Best Regards
Jim

 

[gazdaz36]

This system has hot water priority so your heating will not come on until your cylinder is up to temperature

 

[muggles]

Could be a failing divertor valve

 

[aminuk]

I have the same problem as Bar19191. I have an iStor HE325 which had a new PCB fitted a year ago. It has run OK since then but this week will not fire the burner to run the CH. All 16 programmes are set to provide DHW and CH from 0600 - 2300 every day. The programme control sliders are set to "Auto" and "Run". The programme info shows "12" and the lightbulb during the day - i.e. CH (1) and DHW (2) are on. If you run a hot tap then the burner will kick-in to heat the cylinder and the LCD status shows the "t" symbol. However, once the DHW is up to temperature, the LCD reverts to "0", the burner will not then fire up for the CH program. The grey CH temperature knob is set to max and the thermostat is set to 30 degs., radiators are set to max but the burner does not kick in and the LCD does not move to "c", it stays at "0" (no demand for heat).

Any ideas ? - could it be the thermostat not demanding heat ? (it does click at the ambient room temp). Need to get this fixed before it gets really cold. Thanks.