Yes, flex stainless steel connectors can be used on water heaters for safe and flexible plumbing connections, ensuring durability and resistance to corrosion.
Flexible stainless steel connectors are common in plumbing, but using them on water heaters requires careful consideration. This guide covers when flex stainless works, code requirements, and safer alternatives.
Is Flex Stainless Safe for Water Heaters?
Flexible stainless steel connectors can be used on water heaters if they meet three key requirements:
- Rated for minimum 150 psi working pressure
- Designed for temperatures up to 180°F
- Certified to ANSI/NSF 61 for potable water
The International Association of Plumbing and Mechanical Officials (IAPMO) requires connectors to withstand 210°F for residential water heaters.
When Flex Stainless Works Best
These situations allow flex stainless connectors:
| Application | Recommended Type |
|---|---|
| Tankless water heater connections | Braided 304 stainless with brass fittings |
| Short runs (under 24″) | Corrugated stainless with dielectric unions |
| Vibration-prone installations | Double-braided stainless with vibration loops |
Code Requirements for Water Heater Connections
Most plumbing codes specify:
- 18″ minimum rigid pipe before any flexible connection
- Dielectric unions required when connecting dissimilar metals
- Shutoff valve within 5 feet of water heater
For tankless water heaters with recirculating pumps, some areas require earthquake straps with flexible connections.
Common Code Violations
Avoid these mistakes with flex connectors:
- Using washing machine hoses (max 125 psi)
- Oversized connectors that sag and trap sediment
- Missing temperature/pressure relief valve extension
Better Alternatives to Flex Stainless
For safer installations consider:
1. Semi-Rigid Copper Connectors
Type L copper with proper bends handles vibration better than flex in many cases.
2. CSST Gas Connectors
For gas water heaters, corrugated stainless steel tubing (CSST) works when properly bonded.
3. Dielectric Unions
Required by code when connecting copper to steel water heater nipples.
Installation Best Practices
Follow these steps for safe flex stainless installation:
- Measure exact length needed (no slack)
- Support pipes within 18″ of connections
- Use two wrenches to prevent twisting
- Check for kinks after pressurizing
The International Code Council Evaluation Service maintains a list of approved connectors for plumbing applications.
Maintenance Tips
Inspect flex connectors annually for:
- Braiding corrosion (white powder or rust)
- Bulging near fittings
- Mineral deposits at connection points
Replace any questionable connectors immediately – a failed water heater connection can cause thousands in water damage.
