I had a 10 hr round trip to Derry to put a analyzer in a boiler, so my sarcastic side came outThat proves the opposite of what you were saying.
How could you doubt meyou said it couldn't be done.
a twin coil cylinder would be the advised installation with UK regs.
that doesn't mean it can't be done, just boiler manufactures won't support it, .
To clarify i am talking about two types of installation, the correct way and the fruit loop way, i have only seen the correct way in books(i am not a plumber just a gas fitter), but i have seen the fruit loop way a few times and any posting about not being able to add the a back boiler/stove would be aimed at the fruit loops, you and Villa1 may not be aware of how many fruit loops are actually out there, i have seen thousands of installations and the fruit loops seem to out number competent installer 10/1, so i wouldn't be as confident as Villa in finding someone with the skill to install safely, Gary.