PEX manifolds and PEX plastic ducting have cost advantages associated with installation compared to traditional rigid pipe ducting systems. PEX pipe manifolds and PEX pipe are part of a relatively new approach to residential water supply, but they have gained widespread acceptance in the home building industry.
The manifold acts as a control center, delivering hot and cold water to flexible PEX supply lines from the manifold to individual fixtures. Each fixture essentially has a home run to the manifold, rather than to the mains like traditional mains and branch pipes.
1. How PEX Pipe Manifolds Work
PEX manifolds include separate manifold chambers for supplying hot and cold water lines. The cold water manifold is fed by the main supply pipe and the hot water manifold is fed by the water heater. Water pressure in the manifold is maintained by incoming service lines.
Pipe manifolds are installed in convenient, accessible locations such as basement walls or service rooms to allow individual fixtures to be shut off. If the manifold is plastic, the minimum clearance to the water heater needs to be 36 inches (vertical) and 18 inches (horizontally). Opposed-port manifolds can be easily installed between stud frames.
2. Advantages of PEX Pipe Manifolds
PEX pipe and PEX pipe manifolds have many advantages:
- Pipe manifolds accept all common supply line sizes down to 3/8 inch.
- PEX is flexible and can bend, so it requires fewer fittings than rigid pipes, which means less pressure drop occurs in the pipes.
- Flexible PEX pipe is a better insulator than copper and is less susceptible to rust.
- Because hot water reaches the faucet more quickly, a manifold system reduces energy loss, especially when loops or rings are added to the system.
- Flexible, non-metallic ducting creates a quiet, efficient duct system that won’t suffer from corrosion, scale, or microbial buildup.
- PEX pipe resists freeze damage because it can expand up to 15% without cracking.
- PEX piping manifold systems can save on labor costs.
- Power can be switched off in a central location.
- Manifold systems are available for commercial distribution nationwide.
3. How to install a PEX manifold
PEX manifolds can be installed in almost any location. Start by calculating the number of fixtures or locations that will use cold and hot water, including any ice machines and outdoor fixtures.
Manifolds include plates used to secure the unit to a wall or other surface. For best results, remember these tips:
- Make sure the manifold has enough ports and identify each port during installation.
- To minimize heat loss, install the manifold close to the water heater.
- Water heater outlets should be at least 18 inches away from the manifold.
- Install stop valves and ensure there is sufficient space to operate all valves.
- Most PEX pipe manufacturers have their own mechanical assembly and joining methods, so only materials and tools approved by the manufacturer can be used.
- For low-flow applications, use 3/8-inch tubing; for high-flow applications, use 1/2-inch tubing.
- Includes additional ports on the manifold for future expansion. Cover any unused ports.
- Extend the PEX pipe all the way to the desired location and mark the line at the manifold.
