To install an electric tankless water heater, turn off power, connect water lines, mount the unit, and wire it to the electrical supply following the manufacturer’s instructions.
Electric tankless water heaters provide endless hot water while saving energy and space. Proper installation ensures safety and peak performance. Follow this detailed guide for a successful DIY or professional setup.
Why Choose an Electric Tankless Water Heater?
Tankless models offer significant advantages over traditional tank heaters:
- Endless hot water supply (no running out during showers)
- 50-60% lower energy costs (only heats water when needed)
- 20+ year lifespan (vs 10-15 years for tank models)
- Compact size saves valuable space
For optimal performance, consider the Stiebel Eltron Tempra 36 or other high-efficiency models.
Pre-Installation Requirements
Electrical Needs
Most units require:
| Unit Size | Voltage | Amperage | Wire Gauge |
|---|---|---|---|
| Small (point-of-use) | 120V | 15-20A | 12 AWG |
| Whole-house | 240V | 50-150A | 6-8 AWG |
Water Supply
Ensure your home has adequate:
- Water pressure (40-80 psi ideal)
- Flow rate (match to heater’s GPM rating)
Installation Steps
1. Mounting the Unit
Choose location with:
- Easy access to electrical panel
- Shortest possible water line runs
- At least 12″ clearance on all sides
Use manufacturer’s template to mark and drill mounting holes. Secure with appropriate fasteners for your wall type.
2. Electrical Connection
Critical safety steps:
- Turn off main breaker
- Run appropriate gauge wire from panel to unit
- Install dedicated double-pole breaker
- Connect wires to unit’s terminals (L1, L2, Ground)
According to Energy.gov, proper wiring is essential for safety and performance.
3. Plumbing Connections
For water lines:
- Install isolation valves on hot and cold lines
- Connect with flexible stainless steel hoses or copper piping
- Use dielectric unions if connecting to dissimilar metals
- Install pressure relief valve if not built-in
Consider adding a descaling pump for hard water areas.
4. Final Checks
Before powering on:
- Verify all electrical connections are tight
- Check for water leaks at all joints
- Ensure proper grounding
- Set temperature according to manufacturer specs
Maintenance Tips
Extend your heater’s life with:
- Annual descaling (more often in hard water areas)
- Checking electrical components every 2 years
- Inspecting water connections biannually
- Cleaning inlet filters quarterly
For replacement parts, see our guide to tankless water heater replacement parts.
