How Does On-Demand Recirculation Work?

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. On-demand systems such as AutoHot only turn on when there is hot water demand and if hot water isn’t already at the tap. Anytime 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. 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.

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

Building Energy Code Requirements

Central to a high-performing hot water distribution system is an on-demand recirculation pump. Building energy codes and performance certifications are now requiring that buildings that use hot water recirculation pumps, must also have demand controls to help regulate the system run time for reduced energy losses. Using and specifying the AutoHot system will help your building meet these code requirements and ensure efficient hot water delivery in any application. Look for these requirements in such new building standards such as: 2016 California Title 24, 2015 International Energy Conservation Code (IECC), The Department of Energy Zero Energy Ready Home (ZERH) program, LEED for Homes v4 and others.

Demand Recirculation for Commercial/Multifamily Central DHW

According to research funded by the California Energy Commission, central domestic hot water systems in existing multifamily buildings are only about 35% efficient on average, with approximately one-third of the total energy being lost in the recirculation loop. Why are these recirculation loops so energy wasteful? One of the biggest contributors to these losses are the recirculation pumps, which in most cases are left running on a non-stop, 24×7 basis. This means that every minute of the day that hot water is being pumped out into the building, there is simultaneously unused return water that is being dumped back into the tank that needs to get reheated. Not only is this not necessary, but it results in excessive energy use by the heating system.

The commercial AutoHot is a demand based recirculation control that uses flow and temperature sensors to regulate the run time of the pump. Instead of running 24 hours per day like most systems, central water heating pumps that use the AutoHot will only see about 1-3 hours of run time per day, but will still preserve the same level of hot water service as an uncontrolled pump. This results in total hot water energy reduction of 15-20% on average, while also reducing the occurrence of costly pinhole leaks that may result from non-stop hot water circulation in the pipes.

Building Energy Code Requirements

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