On Fri, 02 Jun 2006 15:18:36 +0100, Doctor Drivel wrote:

It is standard practice to have the boiler gas supply dedicated to the
boiler only and no tee offs.

What 'standard' is that, then?

In the UK the current standard is BS6891:2005 "Installation of low
pressure gas pipework ... in domestic premises". Appendix A of this
standards document explicitly shows how to size pipe to supply multiple
appliances _with_ tee offs.