The question of whether PEX plumbing systems require water hammer arrestors is a complex one that merits careful consideration. While PEX’s flexibility offers some natural shock absorption, this alone may not be sufficient protection against water hammer effects.
Understanding Water Hammer in PEX Systems
Water hammer occurs when there’s a sudden change in water flow velocity, typically from quick-closing valves[4]. Despite PEX tubing’s flexibility, it’s important to understand that this characteristic doesn’t fully mitigate water hammer issues[7]. The material’s elasticity helps absorb some shock, but may not prevent all potential damage[9].
The Case for Water Hammer Arrestors with PEX
Even with PEX installations, water hammer arrestors are often necessary for several reasons:
Quick-Closing Valve Protection
Water hammer arrestors are specifically required for fixtures with quick-closing valves, regardless of pipe material[10]. This includes:
- Dishwashers
- Washing machines
- Sensor-operated fixtures
- Single-lever faucets
Pressure Management
High-pressure systems particularly benefit from arrestors, as pressure should not exceed 80 PSI[8]. When municipal water pressure is high, the combination of:
- Pressure-reducing valves (PRVs)
- Water hammer arrestors
provides optimal protection[8].
Installation Considerations
When installing water hammer arrestors in PEX systems:
Location Requirements
- Install within 20 feet of quick-closing valves[9]
- Place at the last fixture downstream in the system[9]
- Position between the cold water supply line and shutoff valve[4]
Sizing Guidelines
For residential PEX installations:
- Size AA arrestors are typically sufficient[9]
- Larger sizes are reserved for commercial applications[9]
Professional Recommendations
Modern plumbing codes and professionals increasingly recognize that:
- Air chambers are no longer considered adequate protection[9]
- Water hammer arrestors are the preferred solution for both PEX and traditional piping[8]
- Proper strapping and support of PEX lines remains crucial[10]
Code Compliance and Regulations
Building codes across different jurisdictions have specific requirements regarding water hammer protection. The International Plumbing Code (IPC) and Uniform Plumbing Code (UPC) both address water hammer arrestors in PEX installations. These requirements ensure system longevity and prevent potential failures.
Specific Code Requirements
The following situations typically require water hammer arrestors:
- Any quick-closing valve installation
- Systems with water pressure exceeding 60 PSI
- Multi-story buildings with PEX installations
- Commercial applications with high-flow fixtures
Cost-Benefit Analysis
Initial Investment
Installing water hammer arrestors with PEX systems involves:
- Material costs ($20-50 per arrestor)
- Installation labor (if not DIY)
- Additional fittings and supports
Long-term Benefits
The investment in water hammer arrestors provides:
- Extended system lifespan
- Reduced maintenance costs
- Prevention of potential water damage
- Lower insurance risks
Common Installation Mistakes
Improper Positioning
Several positioning errors can reduce effectiveness:
- Installing too far from the fixture
- Mounting horizontally instead of vertically
- Failing to account for accessibility
Sizing Errors
Incorrect sizing can lead to:
- Insufficient protection
- Unnecessary expense
- Reduced system efficiency
Maintenance and Monitoring
Regular Inspection
Maintenance requirements include:
- Annual visual inspection
- Checking for signs of wear
- Monitoring for unusual sounds
- Testing system pressure regularly
Comparing PEX with Traditional Piping Systems
Understanding how PEX differs from other materials helps explain water hammer protection needs:
| Pipe Material | Flexibility | Natural Shock Absorption | Arrestor Requirement |
|---|---|---|---|
| PEX | High | Moderate | Recommended |
| Copper | Low | Minimal | Required |
| CPVC | Medium | Low | Required |
System Design Considerations
Flow Rate Management
Proper system design must account for:
- Maximum flow rates
- Pressure variations
- Fixture unit loads
- System configuration
Temperature Effects
PEX behavior changes with temperature:
- Expansion increases in hot water lines
- Flexibility varies with temperature
- Support requirements change seasonally
Alternative Solutions
Pressure Management Systems
While not replacing arrestors, these complementary solutions include:
- Pressure-reducing valves
- Expansion tanks
- Flow regulators
- Anti-water hammer valves
Professional vs DIY Installation
Professional Installation Benefits
- Proper sizing and placement
- Code compliance assurance
- Warranty protection
- System optimization
DIY Considerations
If attempting self-installation:
- Follow manufacturer guidelines strictly
- Use appropriate tools
- Ensure proper access for maintenance
- Document installation details
Key Takeaways
The decision to install water hammer arrestors with PEX plumbing ultimately depends on specific system requirements, but is generally recommended for optimal protection and longevity of the installation.
Frequently Asked Questions
Q: Can PEX pipe flexibility eliminate the need for water hammer arrestors?
A: While PEX’s flexibility provides some shock absorption, it’s typically not sufficient for complete protection, especially with quick-closing valves.
Q: How often do water hammer arrestors need replacement?
A: Quality arrestors typically last 5-10 years but should be inspected annually for optimal performance.
Q: Can I install water hammer arrestors horizontally?
A: Vertical installation is strongly recommended for optimal performance and longevity.
Q: Do I need arrestors on both hot and cold water lines?
A: Yes, both lines should be protected if they serve quick-closing valves or high-pressure fixtures.
Q: Will water hammer arrestors increase water pressure?
A: No, they maintain existing pressure while absorbing shock waves.
Citations:
[1] https://marketerinterview.com/8-ways-to-enhance-the-seo-of-how-to-articles-for-home-improvement-projects/
[2] https://www.stanventures.com/blog/meta-title-length-meta-description-length/
[3] https://userp.io/seo/seo-friendly-faq-page/
[4] https://www.ezyplumb.com.au/blog/what-is-a-water-hammer-arrestor
[5] https://www.oatey.com/faqs-blog-videos-case-studies/blog/how-do-water-hammer-arrestors-work
[6] https://www.webfx.com/industries/home-repair/home-improvement/seo/
[7] https://www.thebuildingcodeforum.com/forum/threads/pex-and-water-hammer-arrestors.28124/
[8] https://www.oatey.com/faqs-blog-videos-case-studies/blog/banging-pipes-what-pros-should-know
[9] https://www.pmmag.com/articles/86282-water-hammer-update
[10] https://www.reddit.com/r/Plumbing/comments/q8s6kb/12_pex_residential_do_i_need_a_water_hammer/