I have a Halstead Finest Combi boiler, which the CH automatically came on at night and unable to switch it off from the timer. The timer has been replaced but the problem still exists. What can I do? The water is fine, but who needs the heating on in this weather! Thanks

Unita Jogia, July 2010

Thanks M. One switch was full of condensation. Dried it out and appears okay. Saved me a few quid. Thanks again

J, January 2014

Yep. That was exactly what happened with our boiler at 2am. One thing with the Halstead, it's very easy to get at. Took the switch out and flushed it with meths to dry it out.. The diverter valve assembly is weeping past the seals and will need replacing. Fortunately I have a spare that I picked up on eBay. As soon as I applied power it cycled as normal.

Jeremy Zeid (Harrow), October 2010

This sounds like the DHW flow switch is faulty. Seen this before on Halsteads. Look for two transparent boxes inside the boiler if one of them has water or condensation inside this is the fault (the microswitch inside is being shorted by the moisture inside) causing the boiler to run even when there is no demand.

M, July 2010

The boiler has a hot water pre-heat function (button is above the hot water thermostat control), do you have the dhw economy button pressed? If not, the boiler tries to pre-heat the hot water, if the diverter is faulty, this 'pre-heat' water can pass down through the heating system, most likely cause.

Carefree, July 2010