Abstract: A radiant heating system especially useful for floor heating is provided with a fluid flow apparatus that includes means for pumping a fluid such as water, a temperature-responsive actuator and a valve positionable within a valve housing in response to measured fluid temperature. The system includes heat transfer means, typically a tube embedded in the floor that receives heated fluid from the flow apparatus which in turn receives fluid at generally a higher temperature from a fluid heating apparatus such as a water boiler. The amount of heated fluid recirculated to the heat transfer means is controlled by the position of the valve in the valve housing.

Abstract: A sub-flooring mix comprising a composition of calcium sulfate hemihydrate and other additives; and sand and water. Polyvinyl alcohol is added to the composition, which prevents surface dusting when the mix sets.