Have you ever wondered why your tankless water heater still takes a few minutes to get hot water to your faucet?
The number one reason for this is the distance from the tankless hot water heater.
As water sits still in the hot water lines between the on-demand water heater and the faucet—it gets cold.
The next time the faucet is used, the water needs to be flushed before water from the tankless hot water heater can even get there. I invite you to read our guide on exactly how hot water recirculating pumps work here.
In this HomeInspectorSecrets.com guide, you will discover:
- The main difference between dedicated loop systems vs. comfort system
- Why your pump flow rate needs to be high enough (but not too high) for your tankless heater
- Control options for recirculation pumps such as smart plugs, timers, or sensors
You can read see our shortlist of top tankless water heater recirculation pumps below, but keep reading to learn more on how to select the best one for your household needs.
Our Overall #1 Rated Pick
Our overall top pick for the best tankless water heater recirculating pumps is the PROZRTED Smart Instant Hot Water Recirculating Pump System. This circulation pump is designed to be placed under the furthest faucet, so it is compatible with traditional water line systems and has only one installation point in the system. This pump can save up to 10% on your water bill.
What Are Hot Water Recirculating Pumps For Tankless Water Heaters?
Even with a tankless water heater installed, the hot water in your plumbing lines tends to cool off between uses.
This is why you still get cold water coming from your faucets, and waste an average of 12,000-gallons per year in most households.
Adding a recirculation pump can eliminate the need for wasted water by keeping water in the lines heated. I invite you to read my guide on the 7 pros and cons of hot water recirculating pumps right here.
Is The Recirculating Pump Compatible?
Not all water heater recirculation pumps are compatible with on-demand water heaters. We recommend that you check the manufacturer's guidelines to ensure the recirculation pump will work on your tankless unit.
It is essential to check the flow rate required to operate your tankless water heater.
If the flow rate of the recirculation pump does not meet or exceed the required flow rate of your tankless hot water heater, it may not even turn on the appliance.
If the flow rate is high enough to start the tankless water heater, it still may not be substantial enough to maintain the proper flow — possibly leading to harmful short cycling of the tankless heater (rapidly turning on and off).
Will It Void The Warranty?
Many tankless water heaters have warranties that will be void if used in continuous-run scenarios. It is essential to purchase a pump with shut-off features or be prepared to add them to your pump.
Ease of Installation
Installing the tankless water heater recirculation pump at the farthest faucet in the system is typically a much easier installation. These under sink pumps typically come in kits that include accessories for the installation.
When you install recirculating pumps at the tankless water heater, it can require more plumbing knowledge or may require the help of a professional.
How Do Recirculating Pumps For On-Demand Water Heaters Work?
To warm the water—which normally sits in the line and cools—the water must be transferred back to the on-demand water heater.
Tankless water heater recirculation pumps are designed to return the water to the tankless water heater using one of two systems.
1. Dedicated Loops
With the full recirculation pump system option, an additional water line is required for the home's plumbing. This dedicated return line creates a loop in the hot water system bringing it back to the water heater.
The water is then circulated through the loop, warming the water either continuously or at intervals depending on the specific pump and set-up. The water is not left to cool in the pipes; therefore nearly instant hot water is available at the faucet.
A dedicated loop is suited more for new construction or for single-level homes with crawlspaces where adding a dedicated return loop is easier.
2. Comfort Systems With Under Sink Valves
Recirculation pump comfort systems use the existing cold water pipe to send unused water back to the water heater so a dedicated return line isn't needed. This is a cost and time-effective solution for homeowners. These systems have a pump installed at the water heater and a bridge valve under the farthest faucet.
You may also install an under sink pump installed under the farthest faucet eliminating the need for a bridge valve.
The initial cost is lowered and installation is greatly simplified.
Some recirculation pumps are designed with sensors and/or timers. The sensor reads the temperature of the water and shuts the pump off as long as the water is at the preset temperature.
Timers can also be used. A timer allows control of the pump's active times. It can be set to shut off automatically at night, while you’re at work, or when you’re on vacation.
Smart plugs are one way to control recirculating pumps. These intelligent plugs allow homeowners to control the pump through their phone or tablet. You can set a schedule for the pump to activate only when it is needed, or simply tap a button on your phone to turn it on or off.
If combined with a voice-activated smart home system; homeowners can simply call their smart system using their voice, making the pump run before even using a needed faucet.
What Are The Different Types of Hot Water Recirculating Pumps For Instant Water Heaters?
Continuous-run pumps are designed to simply plug in and constantly circulate water with only one available speed/flow rate. These continuously running pumps will work even when you are sleeping or away from the home.
There are continuous run pumps that only have one speed, and there are ones with multiple speeds that gives more control.
Both options must be combined with sensors, timers, and/or smart devices to align with the warranty of most tankless water heaters.
In general, default continuous-run pumps without added timers use more energy than 'smart' hot water recirculating pumps.
Automated Start & Stop
Another variety of pumps have thermostats, timers, and/or smart logic in them. The thermostat only allows the pump to run when the water temperature falls below a set degree.
Timers are used to warm the water at set times of the day when water use is at its highest.
Pumps equipped with smart logic maximize efficiency by lowering water temperatures during times it is not typically called upon or when the water is shut off for an extended amount of time, such as vacations, long weekends, etc.
Aside from continuous-run, pumps with sensors, and pumps equipped with smart logic, the major difference is location.
Some pumps are designed to be installed near the water heater and on a comfort system, which requires a bridge valve between cold and hot water lines under the farthest faucet.
Other pumps are installed under the farthest faucet from the water heater. These pumps serve as the bridge valve between hot and cold lines.
How To Pick The Best Recirculating Pump For Tankless Water Heaters?
When choosing the best recirculating pump for on-demand water heaters, many aspects need to be considered based on household needs. Here are a few buying tips:
1. Power Source
Where the pump installs can be a big factor in purchasing a tankless water heater recirculation pump. This is important to consider because the pump needs a power source.
If the circulation pump mounts under the sink, it must be plugged in somewhere. Likewise, if the pump mounts near the water heater, it will still need a power source.
Although, under sink areas can be tricky to work in, it is important to remember that in a comfort system; both pump options require installation under the sink. Pumps installed at the water heater still require a bridge valve.
2. Installation & Parts
How the pump is installed may also be a big factor without the help of a professional. If a pump is being replaced in an existing system, it may be best to get one that installs the same way in the same spot. This is not always the case, but it is certainly something to consider.
Also, some pumps are sold in kits. If you are handy but not familiar with plumbing fittings, it may be best to consider a pump which comes with everything needed for the installation.
Before purchasing any pump, it may be a good idea to search for instructions to familiarize yourself and make sure that particular installation is right for your level of plumbing knowledge.
Our Reviews of the Best Hot Water Recirculating Systems For Tankless Water Heaters
Our top-rated choice for tankless water heater recirculation pumps is the Prozrted Smart Instant Hot Water Pump System with built-in thermostat.
This pump uses temperature readings to maximize the efficiency of heating your water system reducing up to 94% of electrical use compared to continuous-run models. This pump mounts under the farthest sink from the water heater and includes all parts needed for it's single point installation.
This pump is designed to be maintenance-free, safe for drinking water, and has a max flow rate of 6.1-GPM. It offers three speeds and monitors water use, lowering the waterline temps when not in use frequently. It can also be offered with optional remote control.
This pump as an offers a 2-year limited warranty is easy to install and uses a super quiet brushless DC motor. This allows the pump to be more efficient, durable, and safe, while adding more power.
For over 100 years, Taco has been among the top in their class. They provide home solutions for contractors and homeowners alike. Their products are reliable and these pump systems maintain high-efficiency while achieving maximum energy and cost savings.
This tankless water heater recirculation pump is installed near the water heater, providing an alternative to a power supply needed under the sink.
This pump is designed to be continuously running, but an optional kit can be purchased to maintain water temperatures between 95 and 115 degrees. [Aquastat kit #563-20]
The Taco 006-ST4 is maintenance-free, quiet, and direct-drive to add efficiency and lower power consumption. It is rated for use with drinking water and is serviceable rather than having to replace the entire pump if issues arise.
If a return line is not present, this pump requires 2-point installation. It does not come with the required bridge valve or accessories needed to complete the installation. Taco offers a flange to flange 3-year limited warranty and will replace any part or product proven to be defective within that time.
This Taco tankless water heater recirculation pump mounts under the farthest sink from the water heater. It includes all the accessories needed to complete the single-point installation and does require a power source under the sink.
The pump runs only when activated by the consumer. It automatically senses water temperature saving water, energy, and money.
This means the pump will not run or heat water continuously. Thus, it does require some forethought to activate; giving it enough time to warm the water before needed.
Taco pumps come with a 3-year flange to flange limited warranty for any pump or part proven to be defective.
BACOENG is a highly professional and reliable brand for pumps. They make pumps for commercial and residential applications.
This on-demand water heater recirculation pump mounts at the water heater, eliminating the need for under sink power source.
It is designed to be maintenance free and offers 3 pump speeds to fit household needs.
The pump is food-grade and rated to be used for drinking water. The motor is ultra-quiet and it comes with a 1-year extended warranty. It is sold as a pump only. It requires all needed accessories for installation including a bridge valve.
Our Overall Top Pick: PROZRTED Smart Pump
Our top pick is The Prozrted Smart Instant Hot Water Recirculation Pump for these reasons:
1. Smart Controls
The Prozrted pump offers and array of smart technology. This hot water pump is capable of reading temperatures, acknowledging water usage, and operating at any of three speeds to best fit household needs. This means it will only start and run at the selected speed when temperatures drop below a certain degree. The pump also recognizes when water in not being used and will lower water temperatures while not in use.
2. Ease of installation
Installation of this hot water recirculating pump is straightforward and simple. All accessories needed for the installation come in this system. Placement of this pump is under the farthest sink from the water heater, is a single-point installation, and reduces the amount of warm water potential in the cold water line.
3. All Inclusive
This hot water recirculating system comes with automatic shut-off features which are needed for use with tankless water heaters. Adding features such as thermostats, sensors, and timers can be pricey along with making installation more complicated.