Do you want to learn about the best under sink hot water recirculating pumps?
These water pumps are easily installed under the sink that is farthest from the water heater --- so you can have instant hot water.
In this product review guide, I will go over...
- My #1 top pick for the best under sink hot water recirculating pump
- How under sink water pumps work
- The basics of installing an under sink pump
- The benefits of under sink hot water pumps
Let's get started with this guide!
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2. Taco On Command
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3. Laing E1 Series
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Our Overall #1 Rated Pick
Updated On May 10, 2022
Our overall top pick for the under sink hot water recirculating pumps goes to PROZRTED because it can easily be installed under the sink with a 10-ft power cord. It comes with 10-inch water hoses and valves for a quick connection. The PROZRTED recirculator is rated at 6.1-GPM and comes with 3 operating modes. And at 55-watts, it is energy-efficient and quiet.
What Is An Under Sink Hot Water Recirculating Pump?
An under sink hot water recirculating pump is a special type of water pump that is used to provide instant hot water to your home's fixtures.
The water pump is designed to be installed under the sink farthest from the water heater in contrast to pumps that are installed above the water heater.
All of the plumbing fixtures in-between the water heater and the hot water pump will also get instant hot water --- not just the sink/bathroom with the pump.
How Does An Under Sink Instant Hot Water Circulating Pump Work?
When the pump operates, it sends any lukewarm water in the hot line down the cold water line (and back to the water heater). It basically turns the cold water supply line into a temporary return line --- creating a loop back to the water heater.
Once hot water has reached the water pump, the sensor valve (also known as an aquastat) shuts off the pump and closes the valve --- and the cold water line is no longer used as a return.
Pretty much all under sink hot water recirculation pumps have built-in timers so that you can make sure the pump doesn't operate during the day when nobody is home.
The average home will also save in the range of 3,600 to 12,000 gallons per year.
Built-In Sensor Valves
Under sink water pumps have the sensor valve as a built-in component of the water pump. The sensor valve is a plumbing valve that opens/closes based on the temperature of the water --- this is how the water pump knows when to turn on and off.
Recirculating pumps that are installed above the water heater will not have the sensor valve as part of the unit. Instead, they have a separate sensor valve installed under the farthest sink from the water heater that works together with the pump.
Four Water Line Connections
Under sink hot water circulating pumps have four water connections on the pump, as compared to only two for above heater pumps.
Two of the water lines go from the pump and to the faucet hot & cold. The other two water lines are for the hot and cold water supply lines from the wall.
How Do You Inspect An Under Sink Recirculating Pump?
#1. Securely Attached & Level
Pull and tug on the water pump to make sure it is securely attached to the wall/cabinet under the sink.
#2. Look For Corrosion
With multiple flexible water line connections, there is a possibility for leaking. Verify that the water lines are braided stainless steel and not cheap black rubber. Look for any rusting, leaking, or signs of corrosion at the water connections.
#3. Verify Correct Line Connections
There is a hot & cold side to the water pump. The hot side has a supply hot water connection, and this same side should have a second flexible line going to the hot faucet side (and vice versa). Make sure they aren't mixed up.
How To Install An Under Sink Hot Water Recirculating Pump?
#1. Sink Choice
You want to install the water pump under the sink that takes the hot water longest to arrive from the water heater.
Usually (but not always) this is the sink that is farthest from the water heater.
#2. Outlet Location
Most instant hot water circulating pumps are installed with a standard 3-pronged plug.
If you don't have an existing outlet in your bathroom, or if you don't want to plug it into an above vanity outlet, then you will have to install a new bath outlet under the vanity (preferably inside a cabinet). If you have a bath wall outlet, you can route the plug cord behind the vanity and to the outlet.
#3. Fasten To Wall
It's time to install the water pump onto the wall. Use the supplied bracket and screws with the water pump and fasten it to the wall.
Only mount it in an approved orientation by the manufacturer. Some pumps should only be installed in a vertical direction. Make sure you have access to the timer and any controls of the water pump.
#4. Turn Off Water
Before installing any water connections, be sure to turn off the water.
Simply turn the water valves into a perpendicular direction to shutoff the water if it is a ball valve. If the valve is a circle, it is a push pull type stop valve, and you will have to pull it to shutoff the water.
If you have any doubts, you can also shutoff the main water valve to the entire house.
#5. Remove And Re-Connect Faucet Water Lines
After you installed the water pump onto the wall and under the sink, it's time to remove the flexible water line ends from the faucet.
Depending on your sink setup, these ends under the sink will be either 1/2-inch or 3/8-inch. Do not remove the water line ends coming out of the wall. There will be two metal/plastic nuts that will have to be removed with a wrench.
After removing the water line ends, inspect any existing rubber washers inside of the water lines and make sure they are in good condition. Connect these water lines to the 1/2-inch water pump nipples, and make sure that the hot & water lines are on the correct sides of the pump.
#6. Screw On Water Inlet Lines To Pump
Now you should screw on the flexible water lines to the water pump, the 1/2-inch ends.
Verify that the hot water line goes to the hot water inlet of pump and vice versa. The pump should clearly indicate which side is for hot & cold.
If your water lines are not flexible, or not 3/8-inch to 1/2-inch, buying a new stainless steel braided water lines is recommended.
#7. Screw On Water Outlet Lines To Under Sink
You should take the new flexible water lines that come with the pump, or if you provide your own, and connect them to the faucet.
Make sure that the hot water line from pump goes to the hot water of faucet --- and vice versa. And then connect these lines to the outlet nipples of the water pump.
#.8 Turn On Water
Now it's time to test the system. Turn on the water and visually check for leaks. Also rub your fingers along the connections to feel for any water.
If there are no leaks, plug in the water pump.
What Are The Best Under Sink Hot Water Recirculating Pumps?
Here are my top picks for the best under sink recirculation systems with their features, pros, and cons...
Our overall top pick goes to this PROZRTED under sink recirculator.
This advanced pump can be easily installed underneath your sink with a 10-ft power cord and all of the hoses and connections needed for a fast hookup.
It is rated at 6.1-GPM, and it includes a built-in thermostat that turns on when water drops to 91-degrees.
The PROZRTED recirculator has three operating modes with constant temp mode, smart mode, and manual mode.
And it is pretty quiet with a permanent brushless DC motor and only uses 55-watts.
- High quality ECM motor for quiet operation
- Built-in sensor valve & timer
- Also works great with tankless water heaters
- Complaints of leaking between housing and pump head
The Taco On Command is a high quality under sink hot water recirculation pump
The pump is 1/40-hp and only turns on when the user presses a button --- so it doesn't waste energy and a timer isn't required.
A return line is not required and the installation is easier than above hot water heater installations.
- On demand instant hot water with push button control
- 1/40 HP motor
- Well-known Taco brand
- Must push button to turn on
The Laing LHB under sink water pump is a great pump to give you instant hot water in your household.
The LHB is a 14-watt water pump that comes with a 6-ft power cord and built-in sensor valve for easy installation under a sink.
It comes with a built-in 24-hour timer and it is very quiet --- less than 30 decibels.
- Budget friendly price
- Energy saving using only 14-watts
- Very quiet at less than 30 decibels
- Complaints of poor quality
- May not work properly with tankless systems