Kevplumb your a star , what do you think about the rads getting warm when only the water is on. I have the ch system with a big & small tank in the loft , the cylinder is the type with the coil inside from the ch .
I want to alter pipework- 8mm- to replace old with new radiator upstairs . System has manifolds upstairs & down - under floors. Do I drain system as normal i.e. open drain cock at lowest point etc .Can I part drain ?. CH is about 20 yrs old. has both 8 & 10 mm pipework .
Also when hot water...