How Does On-Demand Recirculation Work?

Historically, most conventional recirculation pumps run for hours during the day, even at times when nobody is using hot water. When this happens, energy is lost and your water heater must continue to fire up and reheat unused water, resulting in high gas/electricity use. Our on-demand recirculation systems only operate when two conditions are met:

  • There is a demand for hot water (as detected by a sensor or switch).

  • There is no hot water presently in the line (as detected by a temperature sensor).

When there is no hot water demand, such as when you’re at work, on vacation, sleeping, or just hanging around the house, the system stays off. When hot water is in the line, such as when it’s coming out of the faucet, or just recently used, the system stays off, even if it continues to sense demand.

Operating in this manner usually results in pump run time of less than 15 minutes per day total, and can achieve upwards of 10,000 gallons of water savings per year at a cost of less than $2.00 in energy to operate the system annually. You can compare this with timer/temperature based systems that sees hours of run time per day, needlessly running and turning on your water heater.

The AutoHot works in any plumbing system, whether you have a dedicated return line or just standard plumbing, and works with any tank, tankless, or heat pump water heater.

For Standard Plumbing Systems, Under Sink Kit Available

For Plumbing with Dedicated Return Lines

For Plumbing With Dedicated Return Lines.
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Determining the correct AutoHot® System for your home is simple.

Our AutoHot® systems are easily configurable to match any situation. Follow the steps below, and if you need help, please do not hesitate to contact us.



The pump size will affect the speed at which the water moves through the pipes. The  larger the house or the more lineal feet of piping, the bigger the pump size you would want to be able to get hot water throughout the house quickly.

  • 55 Series Pump Suitable for homes up to approximately 2,500 sq ft or distances of about 100 ft from the water heater to the farthest fixture.
  • 99 Series Pump Suitable for homes up to approximately 4,000 sq ft. or distances of about 200 ft from the water heater to the farthest fixture.
  • 150 Series Pump Suitable for homes up to approximately 5,000 sq ft. (or more) or distances of about 300 ft from the water heater to the farthest fixture. 

Note: These are approximations only. For accurate pump performance, please download and refer to the Pump Specification Guidelines to see which pump is correct for you.


Are you installing your AutoHot® System on a return line or under the sink at the furthest fixture from the water heater? The install location determines whether you need the “Under Sink Kit (-USK).”

Use a system with “-USK” in the model number if:

  • You do not have a dedicated return line
  • Retrofitting a house without an existing circulator pump
  • You are installing at the end of a “dead-leg” branch line or riser

Do not choose a model number with

  • If you have dedicated return line
  • You are not installing under a sink, but are installing by the water heater
  • You have an existing circulator pump


Select the way in which you will activate the system when you want hot water delivered throughout the house. The AutoHot® System comes standard with one wired stainless steel button, but you may add additional activators and mix and match different activation styles to suit your needs.

  • Wired Decora Rocker Switch (White)
  • Wired Pushbutton (Chrome)
  • Wired Motion Sensor (Ceiling mount or wall recessed versions)
  • Wireless Push Button (Up to 1000 ft. range)
  • Wireless Motion Sensor (Up to 500 ft. range)

AutoHot® Residential On-Demand Recirculation Systems (Base Models)

Part No.ImageDescription
DR000A (Gen 2)Residential AutoHot On-Demand hot water heat Pump ControlResidential AutoHot demand control (Gen2), no pump
DR055A (Gen 2)55-Series pump AutoHot On-Demand tankless hot water heater55-Series pump AutoHot On-Demand tankless hot water heaterResidential AutoHot, 55 series pump, wired and wireless button activator
DR055A-USK (Gen 2)55-Series pump AutoHot hot water Under Sink KitResidential AutoHot, 55 series pump, Under Sink Kit, wired and wireless button
DR099A (Gen 2)99-Series pump AutoHot On-Demand electric hot water heaterResidential AutoHot, 99 series pump, wired and wireless button activator
DR099A-USK (Gen 2)on-demand autohot recirculating water systems for homes.Residential AutoHot, 99 series pump, Under Sink Kit, wired and wireless button

DR150A (Gen 2)Residential AutoHot, 150 series pump, wired and wireless button activator
DR150A-USK (Gen 2)Residential AutoHot, 150 series pump, Under Sink Kit, wired and wireless button

Accessories (for homes, order separately)

Part No.ImageDescription
WR-16A (only needed for Gen 1 controllers)Wireless receiver (for 1st generation models only)
WB-S-16Ahome Wireless push Button for autohot recirculating systemWireless Button Activator: Works up to 1000 ft away in open air
WM-S-16Ahome Wireless motion Sensor for on-demand hot water systemWireless motion sensor
HR-S-17WHardwired Decorative rocker switch whiteHardwired rocker switch activator
HB-S-13AHardwired push button activator for on demand recirculating pumpHardwired push button activator
MBKT-19APump wall mounting brackets, for use with 55, 99, or 150 series pumpsPump wall mounting bracket, set, for 55, 99, and 150 pump
HR-S-17LEDHardwired LED lighted indicator rocker switch. Hardwired LED lighted rocker switch
HB-S-20LEDHardwired LED lighted indicator push button.  Light turns on when hot water is ready, turns off when lines are cool and pump needs to be activated.Hardwired LED lighted button