Yes, you can connect PEX directly to an electric water heater using appropriate fittings, ensuring proper temperature ratings and codes are followed.
Connecting PEX tubing to an electric water heater is a common question among homeowners and DIYers. While PEX offers flexibility and cost savings, proper installation is critical for safety and longevity. This guide covers everything you need to know about PEX-to-water-heater connections.
Is Direct PEX Connection Allowed?
The short answer is yes, but with important considerations. Unlike gas water heaters that require 18″ of metal piping, most electric water heaters can accept PEX directly. However, you must:
- Check local plumbing codes (varies by jurisdiction)
- Verify the water heater manufacturer’s requirements
- Use dielectric unions to prevent galvanic corrosion
- Maintain proper clearances from heat sources
Why Dielectric Unions Matter
Electric water heaters have brass or steel nipples that can react with PEX fittings. A dielectric union creates a barrier between dissimilar metals, preventing corrosion that could lead to leaks. This is especially important in areas with hard water.
PEX Types for Water Heater Connections
Not all PEX is created equal for hot water applications:
| PEX Type | Max Temp | Flexibility | Best For |
|---|---|---|---|
| PEX-A | 200°F | Highest | Best choice for direct connections |
| PEX-B | 180°F | Medium | Acceptable with precautions |
| PEX-C | 180°F | Lowest | Not recommended |
Installation Best Practices
Step-by-Step Connection Guide
- Turn off power and drain the water heater
- Install dielectric unions on heater nipples
- Connect PEX using appropriate fittings (expansion or crimp)
- Support pipes within 12″ of connections
- Leave service clearance for future maintenance
Critical Safety Considerations
Even with electric water heaters:
- Maintain 6″ clearance from electrical components
- Never run PEX through ceiling joists near heater
- Install an expansion tank if required by code
- Consider a thermostat-controlled system for better temperature regulation
When to Use Alternative Materials
While PEX works for most electric water heaters, consider copper or stainless steel flex connectors when:
- Manufacturer specifically requires metal piping
- Water temperatures exceed 180°F
- Local codes prohibit direct PEX connections
- You need rigid piping for vertical runs
For commercial applications or high-temperature systems, professional plumbers often recommend copper for the first 18 inches.
Long-Term Maintenance Tips
To ensure your PEX connections last:
- Inspect dielectric unions annually for corrosion
- Check for kinks or stress on the tubing
- Monitor water pressure (keep below 80 PSI)
- Flush the heater regularly to prevent sediment buildup
For optimal performance, pair your PEX installation with a quality anode rod to protect the water heater tank.
