Learn About Radiant Heating Manifolds

The Different Sizes and Coverage Area

••• Photo Pexmall

Manifolds are like the 'heart' of a radiant floor system. Plumbing Manifolds are that central place where water is distributed into smaller pipes and sent through the radiant heat system. Manifolds are used to distribute water in radiant, snow-melting and hydronic applications.

These centralized systems are made of adapters, end caps and fittings that normally are designed or specified in customize manifolds depending on the intended application. They also have individual shut-off valves allowing to turn-off a single fixture or a specific conduit without affecting other areas of the building. The water valves shall be identified to indicate which plumbing fixture is being controlled from that specific valve.

Manifold Components

A good manifold shall be able to distribute water efficiently and economically when the PEX tubing has been sized properly. When the PEX tubing is designed properly, hot water will flow faster resulting in water and energy savings. Plumbing manifolds are manufactured in different sizes, being the most common ones between 3/8 inch and 1/2 inch Plumbing PEX Pipe.

PEX Manifold Sizes

PEX manifold will reduce the need for soldering copper pipes, flames, and chemicals that could get into the water lines causing obstruction and many other problems. Use of manifolds can speed installation and improve performance on water distribution systems. Plumbing manifolds are normally available in the following sizes are available from Canarsee.COM:

  • 2-branch Radiant PEX Manifold Set for heating systems that will cover a maximum of 800 square feet.
  • 3-branch Radiant PEX Manifold Set used to cover an area between 600 and 800 square feet as well.
  • 4-branch Radiant PEX Manifold Set reaching almost 1,200 square feet.
  • 5-branch Radiant PEX Manifold Set ranging between 1000 and 1300 square foot of floor.
  • 6-branch Radiant PEX Manifold Set enough for an area to be treated between 1300-1700 square foot of floor.
  • 7-branch Radiant PEX Manifold Set is commonly used together with PEX tubing for radiant floor heating in system that covers a maximum of 1900 square foot of floor.
  • 8-branch 3/4" Radiant PEX Manifold Set shall be used when the area to be covered is between 1800-2200 square foot of floor.

Additional models are also available up to 12-branck manifold set that should be enough to cover an area of 2500 square foot of floor. While products vary from one manufacturer to another, they normally include 1 supply side with adjustable flow meters and outlets for PEX tubing, 1 return side with balancing valves and outlets for PEX tubing. Plumbing manifolds shall also contain 2 drain-fill valves with temperature gauges, 3/4" garden hose connection, shut-off ball valves and wall mounting brackets.

PEX Manifolds Considerations

All of these manifolds and their coverage will depend on the size of the PEX pipe used. For a typical slab heating system with 1/2" PEX spaced at 12" OC (On Center) and a 1,500 sqft space, the project would require about 1,500 linear ft of PEX.

Hot and cold water plumbing requires separate PEX plumbing manifolds, they are sized and selected based on the number of fixtures as well as inlet and outlet pipe sizes. Remember a radiant heat system, is not only a good PEX manifold system but also should have the right cables, floor mat, fittings, thermostats and the right PEX tubing.