Yes, you can add a tankless water heater to an existing system, but it may require adjustments to the plumbing, gas lines, or electrical systems to ensure compatibility and optimal performance.
Many homeowners wonder if they can integrate a tankless water heater with their current water heating setup. The answer is yes – with proper planning and installation. This guide covers everything you need to know about adding tankless technology to your existing system.
How Tankless Water Heaters Work With Existing Systems
Tankless water heaters provide hot water on demand rather than storing it in a tank. When added to an existing system, they can serve two primary functions:
- Primary heater: Completely replaces your tank water heater
- Supplemental heater: Works alongside your existing tank heater
Full Replacement vs. Hybrid Systems
For a complete replacement, you’ll need to properly size the tankless unit to handle your home’s peak demand. As explained in our guide on tankless water heater BTU requirements, this depends on factors like the number of bathrooms and appliances.
Hybrid systems combine tankless technology with your existing storage tank. This setup can provide instant hot water while maintaining the benefits of stored hot water.
Installation Considerations
Space Requirements
Tankless units are compact but have specific installation needs:
| Location | Requirements |
|---|---|
| Indoor | Proper venting, clearance space |
| Outdoor | Weatherproofing, freeze protection |
Plumbing Modifications
Your existing plumbing may need adjustments for:
- Water line sizing (often requires larger pipes)
- Gas line upgrades (for gas models)
- Electrical requirements (for electric models)
Benefits of Adding Tankless to Existing Systems
Improved Efficiency
Tankless heaters only operate when needed, reducing energy waste. According to Energy.gov, they can be 24-34% more energy efficient than conventional storage tank water heaters.
Endless Hot Water
No more running out of hot water during back-to-back showers. Tankless units provide continuous hot water flow.
Space Savings
By eliminating the storage tank, you free up valuable floor space in utility areas.
Potential Challenges
Initial Cost
Tankless water heaters have higher upfront costs than conventional tanks, but often pay for themselves through energy savings over time.
Retrofitting Existing Homes
Older homes may require significant upgrades to accommodate tankless systems, including:
- Electrical service upgrades
- Gas line modifications
- Venting system changes
Hybrid System Options
For homes where full conversion isn’t practical, consider these hybrid approaches:
Tankless as Primary with Small Storage Tank
The tankless heater handles most demand while a small buffer tank provides quick hot water at fixtures far from the heater.
Recirculation Systems
As discussed in our article on tankless recirculation pumps, these systems minimize wait times by keeping hot water moving through pipes.
Professional Installation Recommended
While some homeowners attempt DIY installations, professional installation ensures:
- Proper sizing and placement
- Correct venting and gas/electrical connections
- Compliance with local codes
- Optimal performance
According to plumbing experts at This Old House, improper installation can lead to performance issues and even safety hazards.
Maintenance Requirements
Tankless systems require regular maintenance to prevent mineral buildup and ensure efficiency:
- Annual descaling (more frequent in hard water areas)
- Filter cleaning
- System inspections
Consider using a quality tankless water heater descaler for maintenance.
