HI, hope someone can help. I am renovating the bathroom and need to replace the radiator. The old radiator has a twin entry valve on one side. This is the only twin entry valve in the house which has a combi-boiler. Can I connect the new radiator to the old valve or does it need to be replaced with a new valve either end and if so does the central heating system need to be drained down. Thanks for your help in advance.