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 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 |
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.
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.