Drained, flushed and refilled the combi CH system yesterday, using new additive. Checked condensate drain and expansion pressure and had a look at the caps. on the circuit board. Rather onerous job due to the wind! Hoses out of both doors, but I couldn't use the door from kitchen to hall as doors would have been slammed violently, so was running around the house. Then had to run it up a bit to mix in the gunk, so getting even warmer! If I do this when heating is actually needed the house gets cold; if the weather's OK for open doors...!
Anyway, started out with 3 radiator keys stragetically distributed; ended up with 1 hidden in a pocket and still can't find the other 2. Do the bloody thing migrate in Autumn?