Main components of Radiant Heating Manifolds

A PEX Manifold serves as a hub that distributes hot water from an inlet to zones (valves, air vents, shut off and drain valves, as well as temperature gauges.  Depending on system design and the number of circuits, a manifold can have anywhere from 2 to 12 branches.

In an instance where circuits that are connected to a manifold vary in length, a flow balancing valve is needed in order to control the flow rate of hot water and maintain equal temperature.  Balancing valves allow for increased flow to larger circuits, since they require more heat, while reducing flow to shorter circuits, since they require less heat to maintain the same system-wide temperature levels.  Flow indicators are often present on each circuit of the manifold in order to enable monitoring of water flow in each PEX line.

Air vents act to eliminate any air that gets into the system, thus making it more efficient, while shut off and drain valves allow for completely shutting, disconnecting, draining and refilling any loop without disruption to the rest of the heating system.  Temperature gauges measure the temperature of incoming and returning water flow.

In order to make manifolds as universal as possible, special adapters are used that enable the connection of a manifold to a variety of pipe types and sizes.  A manifold is usually mounted using special PEX manifold mounting brackets.