I install new radiators regularly, sometimes due to a leak, sometimes just for an upgrade like these ones. It's rare the existing pipes are in good enough condition if they've been painted over 10 times, or they're not quite the right size for the new radiator. Usually this can be remedied by lifting the floorboards and adjusting the pipes. But that's not always the case. When the flooring can't be touched there are other means to make it look decent.