how to use?

Any particular one?
Combi, or system boiler?

Just the combination range (All quoted have various models):
Sine T3W (18, 20, 25 etc)
VCW
VUW Turbomax (mark I and mark II)
Turbomax plus
Ecomax (mark I and mark II)
Ecotec (plus, pro or exclusive)

ALL operate differently.
Just to point out how ridiculous your question is.
Some people shouldn't be allowed near computers either.

PP
March 2011