what you need to do is fill the void with loft insulation then double board the plaster board (15mm Soundblock) on the outside. do not press the loft insulation too tight as this will cause to reverse to happen ( noise ). forget armaflex.
a normal meter will provide 6m3 per hour. your 612 will probably not use more than 2m3 per hour. The boiler should be no less than 18mbr (unless manufacturers instructions say otherwise).
22mm will be sufficient on the gas pipe unless pipe is over 12m in length (allow reduction to the overall...
yes, but if in plastic then you may want to tape them with 'metal detecting tape' from speedfit et al. allows you to find the pipe before putting a picture hook into it!
i agree with the others as to boiler sizing. i fit un-vented units atleast 3 days a week and i don't like 'range'. fit an ariston (yes, you heard right!), vaillant or megaflow. but if you fit a cylinder at this stage on a 25 yr guarentee then buy one that has 2 heating coils so that you can add...