There are plenty of internet resources which will help you to size your rads. I installed an entire system, including combi boiler, in a two bed terraced house - BUT - I had a Corgi gas fitter to make the final gas connections and to test the system. Can't be too careful, and anyway, I think it's the law!
Without wishing to kick off a whole lengthy debate because it has been done to death here in the past, the law requires that anybody doing gas fitting is "competent" but doesn't define it. It does require anybody doing so professionally to be a CORGI member.
There is a good FAQ on this referenced by Ed Sirett's signature.
The challenges are not quite on the level faced by Werner von Braun but there are specific design and test rules and the work must of course be to high standard. e.g. this is not something for somebody who has not done plumbing with soldered fittings and without leaks.
.andy
To email, substitute .nospam with .gl
The issues around placement of the boiler in the bathroom are essentially the same as 'may I install a washing machine in the bathroom'? I.e a fixed metal cased electrical appliance. In a cupboard should be OK.
Take account fo the flueing requirements and there costs this can be siginificant.
Download the instructions and read them carefully before finalizing the design and buying the kit.
Unless you are confident to make soldered copper joints leave the gas to a pro.
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