Wanting to fix a K2 600 mm by 600 mm rad to what I think is a plaster skimmed brick wall. I'm fairly sure there isn't a cavity (the houses in this area (north-west London) are known for being badly insulated) - it originally was an outside wall and seems to have about 20 mm of plaster. I want this to be secure as possible so want to go deep into the brick. Is using something like 10 X 80mm Rawlplug FFI frame fixings overkill or quite sensible? I think the hex head ones rather than the countersunk head would be better for the metal brackets: https://www.screwfix.com/p/rawlplug-universal-ffi-frame-fixings-10-x-80mm-50-pack/38928 How many fixings per bracket? Is two enough or should I go for four to be on the safe side?