Im going to a job tomorrow which i have to fit a new rad on a system that is iron pipe, i have got a rad the same size but they want new valves. I dont want to drain down and spend all day filling up & getting rid of the air, if i put plugs over the expansion & in the header tank and got my towels out and flippers on do you think i could undo the valves (threaded) and work on them without flooding the place out. I dont really like freezing iron, and it is on the ground floor in the toilets so shall i go for it or not, any past experiance as i never get jobs on iron. thanks