The Benefits of Using PEX Plumbing Manifolds

Plumber working on pipes under kitchen sink
••• Robert Daly / Getty Images

Plumbing manifolds can be the solution to high fluctuation costs of copper piping. PEX plumbing manifolds are a new method for residential water distribution, gaining acceptance in the home building industry. Manifold plumbing systems are control centers for hot and cold water that feed flexible PEX supply lines to individual fixtures. Manifolds together with a plastic piping offer installation-related cost advantages over conventional rigid pipe plumbing systems.

How a Plumbing Manifold Works

Separated manifold chambers or separate manifold plumbing systems can serve hot and cold water lines. The cold water manifold is fed from the main water supply line, and the hot water manifold is fed from the water heater. Water pressure in manifolds is maintained by the incoming service line.

A water line dedicated to each fixture originates from a port in the manifold. Manifold plumbing systems can be centrally located at the water service line entry point, or in larger homes or apartment buildings, mini-manifolds can service remote fixture groups.

Plumbing manifolds are mounted in a convenient, accessible location, such as a basement wall or a service closet, to allow access for shut off to individual fixtures. Minimum clearances of 36-inches (vertical) and 18-inches (horizontal) are needed between a thermoplastic manifold and a water heater. Opposing port manifolds can be mounted conveniently between stud framing.

Plumbing Manifold Benefits

  • Plumbing manifolds can accept all common supply line sizes, down to 3/8-inch.
  • Fewer fittings are required, so less pressure drop will occur in the lines.
  • Manifolds are corrosion resistant and make service relatively simple.
  • Flexible PEX piping is also a better insulator than copper and not susceptible to rust.
  • Less energy and water are wasted as hot water arrives faster at the tap, especially when a loop or ring is added to the system.
  • Flexible and non-metallic pipes result in a quiet and efficient plumbing system that doesn’t suffer corrosion, scaling or microbiological build-up.
  • Flexible polybutylene pipes reduce the chance of pipes bursting from freezing.
  • The PEX plumbing manifold system can save on labor costs.
  • Leaking is controlled due to the visibility of all connections at either the manifold or the fixtures in a parallel or home run system.
  • Turning off the supply can be done at a central location.
  • Manifold systems are available for commercial distribution nationwide.
  • Manifold systems require planning to determine the optimal manifold location and routing of branch lines.
  • Manifolds carry warranties of 0 to 10 years after the date of installation, depending on the material.

How to Install a PEX Manifold?

A PEX manifold can be installed at almost any location. Start by counting the number of fixtures or location on which cold and hot water will be used, including the ice maker and outside connections. Manifolds will have a plate that can be attached to the wall on which the manifold will be installed.

  • Make sure that the manifold has enough outputs as required and identify during the first step.
  • It is recommended to install the manifold close to the water heater to maximize hot water usage.
  • Do not install the manifold closer than 18 inches from the water heater outlet.
  • Nail the plate to the wall and the manifold to the mounting bracket.
  • Install the shut-off valves, making sure that there is enough room to operate all valves.
  • Using PEX piping, attached 1/2-inch pipes to the inlets and outlets tighten, remember that most PEX piping manufacturers have their own mechanical fitting and joining methods. 
  • 3/8-inch piping may be used for lower flow applications and 1/2-inch piping is recommended for higher flow applications. 
  • If you have unused ports, make sure to cap and close them and remember that for the future there are additional ports if needed.
  • Run the PEX piping all the way to the desired fixture or location, making sure to label the run at the manifold.