.....should the primaries from the boiler go to 28mm? I ask because of a query over a Suprima 50 that runs an average 3 bed semi with a kitchen extension that is now in the process of a loft extension. A HS Megaflo (170 or 210) is going to be fitted and the owner is going to see if the boiler copes before any upgrade decision is made. I may suggest that they upgrade the primaries when the Megaflo goes in to save the floors coming up again later. Presumably the bigger the cylinder the bigger the coil and the bigger the heat transfer. HS's site says to allow the usual 3KW but that doesn't tie in with their coil 'ratings' and 170 and above comes with 28mm fittings. A clue perhaps! Any thoughts guys?
