Installing a tankless water heater yourself is possible but requires plumbing and electrical knowledge; improper installation can void warranties and pose safety risks.
Installing a tankless water heater yourself is possible but requires significant plumbing, electrical, and gas expertise. While DIY installation can save money, improper setup can be dangerous and violate local codes.
Key Considerations Before DIY Installation
Permit Requirements
Most areas require permits for water heater installations. Gas line modifications typically need professional certification. Check with your local building department before starting.
Gas Line Upgrades
Tankless units require 3-4 times more gas flow than tank heaters. You’ll likely need to upgrade from 1/2″ to 1″ gas lines. This is best left to licensed professionals due to explosion risks.
Venting Changes
Tankless heaters need specialized direct venting, not standard chimney flues. Stainless steel concentric vent kits cost $200-$400. Improper venting can cause carbon monoxide poisoning.
Step-by-Step Installation Process
1. Remove Old Water Heater
- Turn off water supply and gas/power
- Drain tank completely
- Disconnect all piping and remove unit
2. Prepare New Location
Choose a spot with:
- Access to exterior wall for venting
- Near existing gas/water lines
- At least 6″ clearance on all sides
3. Install Gas Line (If Upgrading)
For gas line installations, hire a professional unless you have pipe threading experience. Use only approved flexible connectors if allowed by local code.
4. Mount the Unit
Secure to wall studs using manufacturer’s bracket. Ensure unit is level – uneven mounting can damage internal components.
5. Connect Water Lines
Use dielectric unions to prevent corrosion. Install isolation valves and check valves as required.
6. Install Venting
Follow manufacturer specs exactly for:
- Vent pipe material (typically stainless steel)
- Maximum vent length
- Clearance from combustibles
Common DIY Mistakes to Avoid
| Mistake | Consequence |
|---|---|
| Undersized gas line | Insufficient heating, damage to unit |
| Improper venting | Carbon monoxide poisoning risk |
| No expansion tank | Pressure damage to plumbing |
When to Call a Professional
Consider hiring a licensed plumber for:
- Gas line modifications
- Complex venting situations
- Electrical work (for electric models)
- If local codes require professional installation
According to Energy.gov, proper installation is crucial for tankless water heater efficiency and safety. The National Fire Protection Association reports hundreds of gas appliance-related incidents annually due to improper installation.
Cost Comparison: DIY vs Professional
While DIY can save $1,000-$2,000 in labor, factor in:
- Permit fees ($50-$300)
- Specialized tools rental
- Potential code violation fines
- Voided manufacturer warranty
Maintenance Requirements
Tankless units need annual descaling to prevent mineral buildup. Consider installing a descaling pump kit for easier maintenance.
