ok, link below for manual and servicing manual - download/have a read through on the fault finding chart- i'm not fobbing u off here but this is quite an old boiler in our opinion(manual 1993)and has been discontinued - u should be looking to get replaced with a condensing boiler - u probably could qualify for the recently introduced scrappage scheme - but your outlay will still be from approx £600 - £1000 - best to ring around and get some quotes. advise em of existing boiler make/model/ output is between 9.2 to 16.1 kw(pretty small)
nonetheless - as its an older boiler - and having worked on our own old boiler previously - im gonna put my money - in the first instance - on the fan.
when u switch boiler on u should here fan running continuously - if nothing thats ur problem. from manual looks straightforward enough to remove but working on boiler should be by ur service eng - safety paramount of course - nonetheless in good ole days - remove casing to get access - remove fan - try to turn manually - if sticking/not running freely then application wd40 to spindle(if as my prev its accessible) u can get running again if not seized.put back and try sys.
worth ringing around for cost of replacement fan/or google for parts/cost of labour if u get someone in-could be other problems/costs to come - u might do what i thinks worth doing and thats to replace.
Above comments given as a gut feeling -im not a service eng - so if anyone else wishes to agree/completly disagree this should hopefully help u.
I'm on a Worcester Greenstar Junior condensing boiler - and most are happy with and I havent had any probs whatsoever in 2 1/2 years.
regards/good luck
ed
http://www.worcester-bosch.co.uk/installer/literature/discontinued-boiler-literature/discontinued-gas-boiler-literature/240-rsf-discontinued-december-1997-literature
eddie
January 2010