Baxi Combi 133 HE Plus boiler-heating coming on whenshouldnt

6 Sep 2011
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United Kingdom
Help, I have a Baxi Combi 133 HE Plus boiler. The heating has started sporadically started coming on this week when it should not. The timer is set to off position, the thermostat is at its lowest position and the central heating control knob is turned to its lowest point. Why is the heating coming on occasionally? Many thanks in advance for any guidance.
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Does your boiler have a DHW preheat which you have inadvertently turned on?

Is it installed indoors?

Hi Tony,

The Boiler is installed indoors. I cannot see any DHW preheat so I don't think so, the controls are pretty basic, just a timer, a domestic hot water control knob (no off position, just clockwise/anti-clockwise for the temp), a reset button and a central heating control knob (no off position, just clockwise/anti-clockwise for the temp). It is a combi boiler so the water just heats up when the hot tap is turned on.


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