1: seeing as you have just moved in and been 'saddled' with the boiler, you probably have other major expenses to deal with. The diagnosis of gas valve sounds correct and will get you through a doubtless uncomfortable period.
2: Look to change to a new boiler during the summer when things are quieter for installers, a combi in a 3 bedroom house is usually sufficient and would suit needs of most families.
3: When considering a combi, the main issue is water flow (lower in general than a conventional cylinder system), a 24kw boiler will easily cover the heating needs, however the higher the KW rating, the better the hot water output, the heating (generally speaking) can be adjusted down to suit the system requirements.
Worth looking at 28, 31,35 or even 37kw boilers, depending on your own HW requirements.
You will also get what you pay for, my own preference are Vaillants, though others will advise Worcesters etc. That would be down to a choice by yourself.
Carefree
February 2011
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