In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
I am having a radiant system installed in my house. About ½ the area is tube in concrete slab, and the rest is staple up in joist bays – therefore there are 2 different supply temperatures. The boiler is a Triangle Tube that has 2 separate outdoor reset curves. The manual says that the boiler will supply water temperature to satisfy the highest ODR curve when there are 2 zones calling for heat. The contractor wants to put in a thermostatic mixing valve to prevent the slab from receiving the higher temperature water when this happens. Seems to me that this is basically eliminating the ODR on the slab side as it will always get the design temperature water when the joisted area is always calling for heat unless ODR curve of the higher temperature lzone falls below the mixing valve setpoint. Is this acceptable or should I ask for an ODR mixing valve?