How does water underfloor heating work?

Warm water is pumped from the heat source to the manifold. If the floor heating requires warm water, the thermostatic valve will open allowing heated water into the manifold. From the manifold, heated water is pumped around the floor heating pipes, returning to the manifold and then either released back to the boiler/heat source via the boiler return valve for re-heating or blended back into the floor loop via a one-way valve. When all rooms reach desired temperatures, the room thermostats will signal to the actuators and pump to shut down, this in turn stops heated water circulating through the floor.