We only seem to be getting central heating when the water is switched on. It does not come on when heating is selected, and yet even when heating is switched to off, it still comes on when the water heats up. Where should I look for the problem - is it likely to be the programmer? It's quite an old Honeywell, digital (just).
Thanks very much for your help. I have a drayon mid-position actuator, BGMVSP-23. The black plastic switch appears to be moving when the CH is called, but I am not sure if it is moving freely. The CH doesn't call the boiler to ignight, only the HW. I think I will call my plumber - would you expect that to be an expensive fix?
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