Do I need a 2nd gas meter or will upgrade suffice?

[Cerendib]

There are a number of manuals that describe the working of the GS(IU)Regulations, they are all around £50 to £60.

NICEIC Domestic Gas Safety Parts 1 and 2
BPEC Core Domestic Gas Safety
Logic Certification Gas Safety Training Manual

plus others, but they are all in a very similar format reflecting the GS(IU)R into real life situations.

With respect to rated capacity. CE rules determine that the legally required number is the Manufacturer's stated net input in KW.

All gas appliances currently sold in the UK must be CE marked.

Having said the above, my advice remains to find a local reputable Gas Safe Registered installer who can talk you through the process and develop a cost effective solution for you. That is what they are trained (and legally registered) to do.

On the basis that one opinion is good but two is better, I have just got two separate (Gas Safe Registered) plumbers to have a look and give me their advice. One said I'd need a separate supply feeding a second U6 meter, the other said replacing the U6 with a U16 would be sufficient; together with my installer who thinks the current supply is good enough for a second meter and the Cadent engineer who gave both views I have no shortage of (differing) opinions. Hmmm.
Since my gas supplier has already told me that a U16 meter would still be within a domestic tarif I know which option I'd prefer.

Many thanks Brambles for the above manuals info, will try to locate them and do some calculations myself for my own piece of mind if nothing else.