hello we also have a model same as you but we do not have a manual/user instructions. as my hubby is an electrician if he has a copy of the manual then maybe able to help. if you could kindly email a copy he will look through to see if there is a possible answer to your fault code f4 our email is (gibbons12@gibbons12.karoo.co.uk) we look forward to helping each other.
andy gibbons, October 2008