Can PEX Be Used Directly From an Electric Water Heater?

Yes, PEX can be used directly from an electric water heater for hot water supply, ensuring proper fittings and temperature ratings are adhered to.

Connecting PEX tubing directly to an electric water heater is a common question among homeowners and plumbers. While PEX offers flexibility and cost savings, there are important factors to consider before making this connection.

Pex connection from electric water heater setup guide

PEX and Electric Water Heaters: The Basics

PEX (cross-linked polyethylene) tubing has become popular for plumbing due to its flexibility, durability, and lower cost compared to copper. When it comes to electric water heaters, the rules differ from gas models.

Manufacturer Specifications Matter Most

Most electric water heater manufacturers allow direct PEX connections if their installation manual permits it. For example, Rheem’s installation guide specifically mentions PEX as an acceptable connection method. Always check your heater’s manual first.

Temperature Considerations

Electric water heaters typically operate at 120-140°F, well below PEX’s maximum temperature rating of 180-200°F. This makes them safer for direct PEX connections than gas models with hot exhaust vents.

PEX connection from electric water heater

Code Requirements for PEX Connections

Plumbing codes vary by location, but most don’t prohibit direct PEX connections to electric water heaters. The key factors are:

  • No national code requires 18″ of copper for electric heaters (unlike gas)
  • Local codes may have specific requirements
  • Manufacturer instructions override code in most cases

Zurn PEX Installation Guidelines

According to Zurn’s installation guide, PEX can connect directly to electric water heaters for residential applications. They recommend using brass threaded adapters for best results.

Best Practices for PEX Water Heater Connections

Even when allowed, follow these professional tips:

  1. Use PEX-A tubing for better heat resistance
  2. Install dielectric unions to prevent corrosion
  3. Leave some slack for expansion/contraction
  4. Support pipes properly near connections
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When to Use Metal Connectors

Some situations still call for metal connectors:

  • If manufacturer requires it
  • For commercial applications
  • When local code mandates it
  • With tankless electric heaters (higher temps)

Comparing PEX to Other Connection Methods

Material Cost Installation Electric Heater Compatibility
PEX $$ Easy Usually allowed
Copper $$$$ Moderate Always allowed
CPVC $$ Easy Often allowed
Stainless Flex $$$ Very Easy Always allowed

Potential Issues With Direct PEX Connections

While generally safe, be aware of these possible concerns:

Temperature and Pressure Valve Discharge

The T&P valve releases water at 210°F when triggered, which exceeds PEX’s rating. This is why some pros recommend at least 12″ of metal pipe for the discharge line.

Expansion and Contraction

PEX expands more than metal when heated. Use proper supports and allow for movement to prevent stress on connections. Consider using a flexible connector if needed.

Professional Recommendations

Most licensed plumbers suggest:

  • Direct PEX connections are fine for residential electric heaters
  • Use quality brass fittings (not plastic)
  • Follow all local codes and manufacturer specs
  • Consider stainless steel flex connectors for easiest installation

For complex installations or commercial jobs, consult a professional. The right tools and experience make all the difference in plumbing work.

Final Verdict

In most cases, yes – PEX can connect directly to an electric water heater when the manufacturer approves it and local codes allow. Always verify these requirements before proceeding with your installation.

Joye
Joye

I am a mechanical engineer and love doing research on different home and outdoor heating options. When I am not working, I love spending time with my family and friends. I also enjoy blogging about my findings and helping others to find the best heating options for their needs.