don't listen to that nugget.
the celsia is a potterton boiler (british), manufactured for british gas, exactly the same as the prima f range. yes they are getting old, but are also pretty reliable, and as far as i'm aware you can still get pretty much all of the parts. where i'd agree that worcester boilers are up there with the best, they're owned by bosch, who are german.
to answer your question, the re-set is on the underside of the boiler through a small hole hole in the plastic controls cover. it will look like a round button (usually red / brown) with a cross on it. it only goes off if the boiler overheats, if that doesn't work then the most common fault i've seen on these boilers is a siezed fan of a faulty circuit board.
you can look up the instructions on www.partsarena.com/baxi and follow the links for the potterton prima f
hope that helps.
Ian, March 2010
