Can You Use PEX for Electric Water Heaters Under NPC?

Yes, PEX can be used for electric water heater connections under the National Plumbing Code, provided it meets local code requirements and is rated for hot water use.

Many homeowners and plumbers wonder if PEX piping is acceptable for electric water heater installations under the National Plumbing Code (NPC). The answer depends on several factors including local codes, manufacturer requirements, and safety considerations.

Pex pipe installation for electric water heater safety

PEX Piping and Electric Water Heaters

PEX (cross-linked polyethylene) tubing has become popular for plumbing due to its flexibility, durability, and ease of installation. However, its use with water heaters requires careful consideration.

NPC Requirements for PEX Near Water Heaters

The National Plumbing Code generally allows PEX for electric water heater connections, but with important caveats:

  • Some jurisdictions require 18″ of metal piping at water heater connections
  • Manufacturer specifications may override code allowances
  • Temperature and pressure ratings must be considered

According to Vanguard Pipe’s installation guide, PEX can connect directly to electric water heaters using standard metallic termination fittings.

Gas vs. Electric Water Heater Requirements

The rules differ significantly between gas and electric units:

Water Heater Type PEX Connection Requirements
Gas Minimum 18″ metallic piping required before PEX connection
Electric PEX can connect directly with proper fittings
PEX installation guidelines for electric water heater

Key Considerations for PEX Installation

Temperature and Pressure Ratings

PEX tubing must handle the maximum temperature and pressure of your water heater. Most PEX can withstand:

  • Temperatures up to 200°F (93°C)
  • Pressures up to 160 psi at 180°F

Check your electric water heater’s specifications to ensure compatibility.

Manufacturer Requirements

Some manufacturers specify connection methods in their installation manuals. For example, certain tankless units require 18″ of copper before switching to PEX.

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Local Code Variations

While the NPC provides guidelines, local jurisdictions may have additional requirements. Always check with your local building department.

Installation Best Practices

Proper Fittings and Connections

Use manufacturer-approved fittings when connecting PEX to water heaters. Common options include:

  • Brass swivel elbows
  • Stainless steel crimp rings
  • Approved push-to-connect fittings

Support and Protection

Properly support PEX piping near the water heater:

  • Use hangers every 32″ on horizontal runs
  • Protect from sharp edges and potential damage
  • Allow for expansion and contraction

Safety Considerations

Pressure Relief Valve Piping

The NPC requires specific materials for temperature and pressure relief valve discharge piping. While some PEX may be approved, check local codes.

Recirculation Systems

For systems with recirculation pumps, ensure PEX can handle continuous hot water flow.

Alternatives to PEX

If PEX isn’t suitable for your installation, consider:

  • Copper piping
  • CPVC piping
  • Stainless steel flexible connectors

Each material has advantages and limitations for water heater connections.

Professional Installation Recommendations

While PEX is DIY-friendly, complex water heater installations may require professional help. Consider hiring a licensed plumber for:

  • Whole-house repiping projects
  • Tankless water heater installations
  • Commercial applications

Proper installation ensures safety and compliance with all applicable codes.

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.