Two of my 2d floor radiators were making excessive clanging noises. I adjusted the radiator valve at the end of the radiator (not the on-off valve) all the way open to let steam out.

That stopped the excessive clanging, but now I have to fill my boiler with water almost every day. It seems that the water that is in the pipes is not returning to the boiler. Is the boiler using more water because more steam is escaping from those two radiators whose valves I've opened? Does it harm the boiler to keep adding fresh water?

I've checked all my radiators for leaks and can't find any.

Please advise. Thanks!