I have an addition to a school building that will be housing kindergarten kids. The main school has a hot water boiler that will be generating between 130 F to 190 F to provide hot water heat to perimeter fin tube radiators. I want to use water off of this boiler to also heat the radiant floor. However, the floor heat should be maintained between 90 F and 120 F... a lot lower than the rest of the system. I thought about adding a mixing valve to lower the water temperature, but no matter how much water gets diverted with the mixing valve, the water temperature being supplied to the floor will still be too hot. The simpler, the better. I could use a heat exchanger and additional circulation pump for the radiant floor, but don't want to make it that complicated. Does anyone have any ideas of how I can reduce the temperature to the radiant floor?