porscha, I know nothing about hydronic hot water radiant heating, but I will be waiting to read what replies you get. I am planning to build a workshop about 30'x40' and I am thinking about heating it. If what you mentioned is what I'm thinking of, it could be a possibility for me. I don't need to have the area at house temperatures, just get it comfortable to work in a long sleeve shirt. While I'm looking, I will pass along whatever I find. Have a good one ~ shao