Halstead Ace High

Hello I have the above boiler. I earlier posted I had intermittant domestic hot water it turned out that the fan was very slow to spin so a bit of wd40 and all was well.

Now I have a similar problem with intermittant domestic hot water, the fan spins freely but if i put on the central heating first then turn on the hot water tap it then gives domestic hot water.

Could it still be the fan? my thinking is if it was the fan playing up then surely the central heating would not fire up ( I assume the fan has to run before the boiler fires up to extract fumes and to operate the vacuum switch).

Thanks for past advice

You'll need a new fan soon...WD40 won't last. Of course the forum doesn't advocate any gas/combustion related repairs.

Look at the primary water flow switch...see if it's operating under a DHW demand.

Is the primary water flow switch one of the two micro switches if so I can see the pin operating the switch.
Now the domestic hot water is warm but the central heating is hot

well i would help again but my post was deleted , i guess its not worth helping you then