N
Nordio
may be more use http://www.solidfuel.co.uk/pdfs/link_up.pdf the previous link shows systems not allowed in the UK
I think you are referring to the heat leak radiator being ommited on the schematic.
From the sfa.....
The heat leak radiator is not a safety device but serves to reduce the risk of water boiling and discharging into the header tanks and out the overflow. I am not aware of any legislation which covers this issue.
MI's always superceeds the regs in any case.