I need to strengthen the radiator brackets connecting to the wall. To remove a radiator normally you close a valve on either side. This one seems to be in series with the entire central and hot water system, ie all the heated water flows through it to the rest of the house.
On the outflowing side there is no valve, only a screw connecting the radiator to the pipe. Clearly I dont want to unsrew this end without first ensuring the rest of the houses water flows back out of the pipe. Any ideas?