I have just moved in to an old house with central heating and have a leak on a radiator in bathroom. The rad is shot and needs replacing. It is a single rad and measures in old money 25 x 24 ins. to find a replacement the nearest I could see was 600 x 600mm. My problem is that if I use this size the distance between the two valves measures 630mm. The valve tails will not come out of the old rad. Can I buy just the valve tails or do I have to replace the complete valves??. Also what do I do about the gap difference....Me not a plumber....help