My boiler either fires reliably for hot water, or CH, but not both.
Posted by Gordon C, on
Hi I have an ideal logic 12 boiler and a Honeywell ST9400C timer. A little while ago I noticed that the boiler wouldn't fire up for CH demand. I reset the system by switching off/on the main boiler isolator. The system then fired up the CH, but then it wouldn't fire for HW. I can force it to control one or the other by switching off CH or HW on the timer and resetting. Is this a faulty ST9400C?
