Vokera Unica 32HE humming problem HELP!!

[mushy1234]

I have went to a customers house twice this week. They are complaining about there vokera unica 32HE making a loud humming noise during the night and waking them. I have not witnessed this the two times i have been on site and they said it doesnt happen during the day when they have the boiler running. I checked that it wasn't on the pre-heat water mode, which it was not and also adjusted the fan speed down to see if that would improve the problem, it has not. I have bleed all the radiators making sure there was no air in them. Any advice would be great...

 

[Rickster123]

Please get your post count up to 10 and pm a mod with your gas safe details. We don't discuss boiler faults or repairs on the open forum.

And please don't open multiple threads asking the same question. It's deemed as spamming.

Ta muchly.