Agree with Jonathanb,all good onfo,only add the 30 comes with a seperate jig to you can link up pipework before fitting boiler,good for new sites however there is plenty of room under boiler for access to fittings,time clock is usually not with boiler and extra.
Make sure cut flue is well shamfered and greesed as inner plastic flue elbows securing brackets can break if to much force applied when pushing in
Think you get 3 or 4 months extra cover if you register boiler with pottertons insurance providers
on the 24 have had a few problems with pcb and air presure switch when the performa he(now mains) came out but that seems to be ok now,have put a few 30's in and had no problem,now I have said that ,I bet the phone will not stop today
In the economey range I think this is the best boiler, for rental properties especially
External controls are nice and simple and not flimsy,hot water supply very good (dare i mention it)with correct gas pipe sizing
but this boiler is pipe sizing friendly