An underfloor heating (UFH) manifold is a compact multiport arrangement, which usually includes a series of thermostatically controlled 2-port valves, temperature gauges, a mixing valve and circulation pump. 

Balancing between circuits is achieved using valves placed on the manifold return connections. A mixing valve introduces cold supply as necessary to the hot flow water as it arrives at the manifold, thus maintaining the required water temperature to the circuits. In the event that temperature to the circuits should go too high for any reason, a safety temperature override switch cuts in. 

The concentration of valves at the manifold makes for ease of access during commissioning, and also for any rebalancing of circuits which may be required subsequently.