A recirculating system for a tankless water heater ensures instant hot water delivery by continuously circulating water through the plumbing system.
Tankless water heaters provide endless hot water, but waiting for it to reach your faucet wastes water and energy. A recirculating system solves this by keeping hot water ready at all taps. This guide covers how these systems work, their benefits, installation options, and top products.
How Recirculating Systems Work with Tankless Heaters
Traditional tankless systems heat water on demand, which means waiting as cold water clears from pipes. Recirculating systems create a continuous loop that maintains hot water flow. There are two main types:
Dedicated Return Line Systems
These use a separate pipe to return cooled water to the heater. They’re most efficient but require extensive plumbing work. Ideal for new construction projects.
Comfort System (No Dedicated Return)
Uses existing cold water lines with a thermal bypass valve. More affordable to install in existing homes. Some tankless models include this technology built-in.
Key Benefits of Adding Recirculation
- Instant hot water at every faucet
- Saves 12,000-15,000 gallons of water annually
- Reduces energy costs by 10-15%
- Pays for itself in 2-3 years through savings
- Works with both condensing and non-condensing units
Top Recirculation System Options
Built-In Smart Systems
High-end tankless models like Rinnai’s NPE series feature Smart-Circ technology that learns your usage patterns. The system activates recirculation before typical usage times.
Add-On Pump Systems
| Product | Best For | Pipe Length |
|---|---|---|
| Goulds Laing Thermotech E10 | Single fixture solutions | Up to 100 ft |
| ACT D’MAND Kontrols SS3-200 | Large homes (4000+ sq ft) | 200+ ft |
| AquaMotion AMH3K-R | Standard installations | Up to 600 ft |
Wireless Control Options
Systems like the Rinnai RWM200 module allow smartphone control. Set schedules or activate recirculation remotely through an app.
Installation Considerations
Home Size and Layout
Larger homes need more powerful pumps. The HVAC system layout affects pipe runs.
Water Heater Location
Units far from bathrooms/kitchens benefit most. Consider adding pumps at distant fixtures.
Energy Efficiency
Look for ENERGY STAR certified pumps. Timer controls prevent unnecessary operation.
Maintenance Requirements
Recirculating systems need periodic maintenance:
- Flush the system annually to prevent mineral buildup
- Check valves for proper operation
- Inspect pumps for leaks or unusual noise
- Update smart system firmware when available
According to Navien’s technical specifications, their recirculation systems maintain water within 2°F of set temperature while using minimal energy.
Cost Analysis
A complete system typically costs $500-$1500 installed. Breakdown:
- Basic pump kit: $200-$400
- Professional installation: $300-$800
- Smart controls: $100-$300 extra
The system pays for itself in 2-5 years through water and energy savings. Homes with higher temperature settings see faster returns.
Choosing the Right System
Consider these factors when selecting:
- Number of bathrooms/fixtures
- Distance from heater to farthest tap
- Existing plumbing configuration
- Desired control options (timer, smart, manual)
- Water quality (hard water needs more maintenance)
For most homes, a comfort system with thermal bypass valve provides the best balance of performance and affordability. Larger homes may need a dedicated return line for optimal results.
