Waiting too long for hot water at your tap or shower? Installing a recirculating pump on your tankless water heater is one of the best ways to enjoy instant hot water—without wasting gallons down the drain. Whether you’re a hands-on DIYer or just want to understand what’s involved, this guide will walk you through how to install a recirculating pump on a tankless water heater, what you’ll need, and the best kits to get the job done right.
Quick Picks: Best Recirculating Pumps for Tankless Water Heaters
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Best Overall:
Grundfos Comfort System 595916 Recirculating Pump – Easy to install, ultra-reliable, and works well with most tankless setups. -
Best Budget:
Laing AutoCirc E1 Series Recirculation Pump – Affordable, energy-efficient, and ideal for smaller homes or single-bath installs. -
Best Premium:
TacoGenie Tankless Water Heater Recirculation Pump Kit – Push-button control, premium build, and smooth operation for high-demand homes.
Buyer’s Guide: What to Look For in a Recirculating Pump Kit
- Compatibility: Not all pumps are tankless-ready—choose a model rated for tankless or on-demand water heaters.
- Installation Type: Some systems need a dedicated hot water return line; others can be installed at the farthest fixture using a bypass valve (perfect for retrofits).
- Activation Method: Timer, thermostat, or push-button? Timers are “set and forget.” Push-button offers on-demand hot water and energy savings.
- Flow Rate: Most homes do well with 2–6 gallons per minute (GPM). Too high a flow may cause tankless units to cycle.
- Noise Level: Look for “quiet” or “whisper-quiet” operation, especially if your pump is near living spaces.
- Warranty & Brand: Reputable brands offer better support and longer-lasting parts.
Step-by-Step: How to Install a Recirculating Pump on a Tankless Water Heater
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Plan Your System
Decide if you’ll be installing the pump at the heater (with a dedicated return line) or at the farthest fixture (retrofit/bypass valve system). Review your pump’s instructions and make sure you have all required parts and tools. -
Turn Off Power & Water
Shut off power to the water heater and close the main water supply valve. -
Drain the System (If Needed)
Open a hot water tap to relieve pressure. For full replacements, drain any remaining water from the lines. -
Install the Pump
- Dedicated Return Line System: Mount the pump on the hot water outlet of your tankless heater. Connect the return line from the farthest fixture back to the pump’s return inlet. Secure all fittings and check for leaks.
- Bypass Valve (Retrofit) System: Install the pump at the heater. At the farthest sink, install the bypass valve between the hot and cold lines under the sink. Attach included hoses as directed.
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Connect Power
Most pumps plug into a standard 120V outlet. Secure wiring as needed and use GFCI protection if required. -
Set Timer, Thermostat, or Controls
For timer-based pumps, set your desired schedule. For push-button or demand-based models, install the control button and test operation. -
Restore Water and Power
Slowly reopen the water supply and check all connections for leaks. Restore power to the heater and pump. -
Prime and Test
Run several hot taps until hot water reaches each fixture. Observe pump operation and confirm that recirculation is working—hot water should be available in seconds. -
Finish Up
Clean up, secure all fittings, and ensure instructions for all household members are clear (especially if using push-button or timer controls).
Product Reviews: Best Recirculating Pumps for Tankless Water Heaters
Grundfos Comfort System 595916 Recirculating Pump
- Ideal for retrofits—no return line required (uses a bypass valve at the farthest fixture)
- Whisper-quiet and energy efficient
- Programmable timer for convenience
- Trusted for reliability and low maintenance
- Compatible with most tankless models
Pros:
- Easy installation, clear instructions
- Significant water and energy savings
- Works for most homes and plumbing layouts
Cons:
- Not ideal for very large homes or complex layouts
- Timer setup takes a few minutes
Final Verdict: The Grundfos Comfort System offers outstanding performance for almost any home.
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Laing AutoCirc E1 Series Recirculation Pump
- Designed for single-bath, small homes, or low-flow tankless units
- Auto-activation with built-in temperature sensor
- Plugs into any standard outlet
- Super easy to install and maintain
- Very quiet operation
Pros:
- Great price for reliable performance
- Minimal power use
- Compact and neat
Cons:
- Lower flow—not for large or multi-bath homes
- Limited advanced controls
Final Verdict: The Laing AutoCirc is a simple, affordable upgrade for fast hot water at a single point.
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TacoGenie Tankless Water Heater Recirculation Pump Kit
- Premium push-button on-demand control—runs only when needed
- High flow, low noise, and long-term durability
- Complete kit for easy installation
- Excellent for larger homes or those wanting maximum control
- Installer-friendly with thorough instructions
Pros:
- Top convenience and energy savings
- Premium build and performance
- Installer support and warranty
Cons:
- Pricier than basic models
- Requires some light wiring for button controls
Final Verdict: For the best in instant hot water and system control, TacoGenie leads the way.
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Comparison Table
| Name | Key Features | Specs/Capacity | Price Link |
|---|---|---|---|
| Grundfos Comfort System | Timer, easy retrofit, bypass valve | ~6 GPM, no return line needed | View |
| Laing AutoCirc E1 | Plug-in, auto sensor, compact | ~3 GPM, single bath, temp activated | View |
| TacoGenie Kit | Push-button, high flow, premium | ~6 GPM, on-demand, whole home | View |
FAQ: Recirculating Pumps & Tankless Water Heaters
- Do all tankless water heaters work with recirculating pumps?
No—always check your heater’s specs. Most modern tankless units are compatible, but some older models may not be. - Will adding a recirculating pump void my warranty?
No—when installed per manufacturer instructions, pumps do not void most warranties. Always use compatible brands and follow directions. - Can I install a pump myself?
Yes, if you’re comfortable with basic plumbing and simple electrical connections. For complex layouts or unfamiliar systems, a pro can ensure everything’s perfect. - How much energy do these pumps use?
Very little—especially with timer or push-button controls. They only run when needed, saving both water and energy. - How long does installation take?
For most DIYers, expect 2–4 hours depending on your setup and experience.
Conclusion
Installing a recirculating pump on your tankless water heater is one of the smartest upgrades you can make—ending long waits for hot water and reducing waste. With today’s kits, it’s a project you can handle in an afternoon. Choose the right pump for your needs, follow the step-by-step guide, and enjoy near-instant hot water at every tap in your home. Ready for comfort? Your solution is just a pump away.