I have posted here before about my sunroom radiant system using Dan's from BlueRidge system. I have finished the sunroom and plan on doing the whole house this way but in the mean time I have to heat the sunroom. I figuer I can buy electic radiant or I could connect my sunroom radian loop to my gravity hot water system. My thougt would be to add a taco pump right at the juncture of my hot supply loop and add an aquastat on the cold return of my loop set at 100 or so degrees to control the pump. Either one is going to cost me about $ 150.00 but I could probably reuse the taco an maybe the aquastat on my new modcon boiler setup. What do you think? PS the gravity runs about 160. Tom

I think you should continue working with Dan to accomplish what you want.