On the radiator, you have a bleed valve, you can use that to reduce the pressure. BUT, For 1 radiator, just turn it off at both valves, undo the couplings, 1 at a time, which with the bleed valve open, will allow the water to escape and drain into a container. There is no need to reduce pressure in the complete system. After replacing the radiator, just need to top the system up after opening the valves.
SD
July 2012
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