To be honest i prefer the method of going through the wall since otherwise i would have to organize or get them to organize scaffolding for the roof wich is also asbestos up there somewhere so i don't want to use that option, since that both adds to the cost.
And as for the 22mm water...
Scenario.
6 Bedroom house
27 Rads
Currently have a Floor Mounted Boiler with Flue running up a chimmney on the side of the house.
Behind the boiler is an outside wall with no windows or boundaries near it.
Question 1.
I'm having a Boiler installed (40kw) Worcester Bosch the the guy...