A hot water recirculation pump can reduce the wait at a distant faucet and the water sent down the drain while you wait. Whether it lowers energy bills depends on the controls, pipe insulation and how often it runs.
Choose the best hot water recirculation pump for your plumbing layout and water heater, rather than assuming every circulator is a complete retrofit kit.
The pump moves water around a loop back to the water heater. The water heater supplies the heat; the circulator does not heat or store the water itself.
This guide explains how recirculation works, the main control options, and three models for different installation needs.
In a hurry? These are two retrofit kits and one standalone circulator to compare:
- Watts 500800 / 0955800: timer-controlled retrofit kit for tank water heaters
- Grundfos 595916 UP15-10SU7P/TLC: Comfort System kit with analog timer
- Taco 006-B4: bronze circulator with 3/4-inch sweat connections
Watts 500800 / 0955800 Hot Water Recirculation Kit
- Use: retrofit kit for tank water heaters
- Control: 24-hour timer and thermostatic bypass valve
- Connection: existing cold-water line provides the return path
Grundfos 595916 UP15-10SU7P/TLC Comfort System
- Use: retrofit recirculation kit
- Control: analog timer; 115 V mains power
- Connection: Comfort Valve and two flexible hoses included
Taco 006-B4 Bronze Circulator
- Use: standalone domestic-water circulator
- Control: select external controls to suit the installation
- Connection: 3/4-inch sweat; 115 V
What is a Hot Water Recirculation Pump?
A recirculation pump brings heated water closer to the fixtures before you open a faucet. It can shorten the wait, but delivery time still depends on the pipe layout, controls and whether the loop is already warm.
Some installations have a dedicated return pipe. Retrofit kits such as the Watts and Grundfos below use a bypass valve and the existing cold-water line as the return path instead.
Controls vary. Timers, temperature controls and demand switches are different options; a motion sensor is not standard on every pump, and none of these three listings should be assumed to include one.
Less water may be wasted at the faucet, but circulating hot water also loses heat through the pipes and consumes pump power. Continuous operation can therefore increase energy use.
How Does Hot Water Recirculation Pump Work?
The circulator moves water through the hot-water distribution loop and back to the heater, rather than sending cooled water down the drain.
In a retrofit bypass system, the valve connects the hot and cold lines near a distant fixture. It closes the bypass as hot water reaches it. This can temporarily make water in that cold line warmer.
The benefit is most noticeable where you normally wait a long time for hot water.
The pump still needs time to move cooled water out of the line. It cannot guarantee immediate hot water at every fixture or outside its programmed operating periods.
For more detail on demand controls and energy trade-offs, see ENERGY STAR’s recirculation guide.
Types of Water Recirculation Pumps
Common control arrangements include timed, continuous and temperature-controlled operation. Demand-activated systems are another option; these start when requested rather than keeping the loop warm all day.
1. Time Activated Recirculation Pumps
A timer lets you schedule the pump around normal hot-water use, such as morning showers.
Set the start time according to the manufacturer’s instructions and the time your particular loop needs to warm up.
A timer limits running hours compared with continuous operation. Outside those hours, you may again need to wait for hot water.
2. Always-on Recirculation Pumps
An always-on circulator runs continuously while power is supplied. It does not wait for a motion sensor or for someone to open a tap.
This can keep a loop warm but increases pumping time and pipe heat losses. It is not automatically the cheapest operating mode.
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3. Temperature Activated Recirculation Pump
A temperature-controlled system monitors the water at a sensor and switches circulation according to the control’s set points.
When the water cools, the control can start the pump to bring heated water from the water heater. The pump itself is not a heating element.
The control stops circulation once its temperature condition is met. Savings depend on the complete system and its settings; temperature control alone is not a guarantee of the lowest energy use.
Best Hot Water Recirculation Pumps Reviewed
1. Watts Premier Instant Hot Water Recirculating Pump System
Watts 500800, sold under part number 0955800, is a retrofit kit for a conventional tank water heater. Its 24-hour timer lets you schedule circulation.
Watts 500800 / 0955800 Hot Water Recirculation Kit
- Use: retrofit kit for tank water heaters
- Control: 24-hour timer and thermostatic bypass valve
- Connection: existing cold-water line provides the return path
The kit includes the pump, sensor valve, two supply hoses and connection hardware. It uses the cold-water line for the return path, so it does not require a separate return pipe.
The sensor valve works thermostatically without an electrical connection. The current 500800 manual specifies a maximum operating temperature of 140°F; this is an equipment limit, not a temperature the pump maintains at your faucet.
The amount of water saved depends on your household’s pipework and use. Timer settings also affect running time; there is no fixed daily operating cost for every home.
Pros
- 24-hour timer for scheduled operation
- Bypass valve and supply hoses included
- Retrofit layout does not need a dedicated return pipe
Cons
- Not designed for tankless water heaters
- The bypass can temporarily warm the cold-water line
2. Grundfos 595916 UP15-10SU7P/TLC Comfort System
Grundfos 595916 is the UP15-10SU7P/TLC Comfort System kit with an analog timer. It is another retrofit option where there is no dedicated return pipe.
Grundfos 595916 UP15-10SU7P/TLC Comfort System
- Use: retrofit recirculation kit
- Control: analog timer; 115 V mains power
- Connection: Comfort Valve and two flexible hoses included
Its Comfort Valve routes cooled water from the hot line into the cold return path and closes the bypass as hot water arrives. The timer schedules when the pump runs.
The kit pairs a stainless-steel pump housing with a 115-volt, 25-watt motor, a Comfort Valve and two flexible hoses. The analog dial controls operating times, not the water heater’s temperature.
The pump needs mains electricity. It has no battery backup to keep circulating during a power outage. Confirm compatibility with your water heater before installation.
Pros
- Analog timer for scheduled circulation
- Comfort Valve and two hoses included
- Retrofit installation without a separate return pipe
Cons
- Requires a mains outlet; no backup pumping during outages
- Bypass operation can briefly warm water in the cold line
3. Taco 006-B4 Bronze Circulator Pump 3/4-Inch Sweat
Taco 006-B4 is a standalone 115-volt bronze circulator with 3/4-inch sweat connections. Its 125-psi rating is the maximum working pressure of the system, not pressure the pump adds to your water supply.
Taco 006-B4 Bronze Circulator
- Use: standalone domestic-water circulator
- Control: select external controls to suit the installation
- Connection: 3/4-inch sweat; 115 V
Taco lists the 006 for hot or chilled fresh water in open or closed loops, including domestic hot-water recirculation. Its performance range is up to 11 GPM and up to 9.5 feet of head; those maximum values occur at different points on the pump curve.
Unlike the two retrofit kits above, this model is supplied as a circulator. An installer must select suitable piping, electrical connections and any external operating controls for the system.
Pros
- Low-lead bronze body for domestic-water applications
- Replaceable cartridge allows servicing without replacing the entire circulator
- Compact 3/4-inch sweat connection model
Cons
- Not a complete under-sink bypass kit
- Installation and controls must suit the existing recirculation loop
Choose a retrofit kit if your compatible water heater and plumbing need a cold-line bypass, or a correctly sized circulator for an existing return loop. Match the controls and connections before buying a pump; no model can promise zero waiting time at every tap.