Utilities Test IoT for Water Heater Management

By Claire Swedberg

A wireless solution from Apricity allows companies like Portland General Electric to capture data from residential water heaters, and to remotely turn them on and off according to temperatures and peak demands, using narrowband IoT and Cellular LTE-M.


Several U.S. utility companies are piloting a recently released Internet of Things (IoT)-based solution that enables them to better control power load on their grid by detecting the temperature and voltage of each water-heating unit, and by allowing the units to be turned off when necessary via cellular or proprietary 2.4 GHz LAN connectivity. The solution, provided by Apricity, located in Bend, Oregon, includes IoT-enabled water heater controllers known as Aras, installed inline, using the line voltage as a power supply. Each Ara comes with a built-in Nordic Semiconductor chip to transmit data regarding water heater temperatures and voltage via cellular WAN or 2.4 GHz LAN, as well as a built-in nRF9160 System-in-Package (SiP).

Apricity provides the connectivity and software required to collect and manage water heater data, if a utility requests this. The Aras are deployed at both utility and federal sites for testing, in quantities of fewer than 100 units per test. Each entity (all of which have asked to be unnamed) has its own spin on demand response and data-monitoring needs, Apricity says. By its nature, power usage on the grid is uneven. At certain times of the day, energy consumption reaches a peak. The traditional approach for utilities has been to build enough power plants to provide the capacity to meet peak demands, but most of the day, that level of power isn’t required.

One alternative is a demand-response program by which the company could monitor energy consumption, as well as turn off less-critical devices to decrease the load during peak usage. Utilities use a demand-response program to change the power consumptions of a customer to match the demand for power on the entire grid. Energy companies are continuing to move toward demand-response models to reduce pressure on the grid.

For the past six months, utilities like Portland General Electric have been using the Aras for their demand-response programs to turn off each water heater according to peak demand, and to learn when water heater temperatures drop low enough that the units need to be turned back on. By automatically knowing when each water heater temperature drops below a pre-set temperature, the system can restart that heater, while also saving energy consumption during the unit’s downtime.

Apricity is an engineering and product-design agency. “Our team is passionate about creating quality products that stand the test of time,” says Jacob C. Betcher, the firm’s COO. The Ara solution was designed to help customers respond to power demand, he says, adding, “Energy consumption on the grid is very uneven.” However, many demand-response solutions are challenged with connectivity issues when sending data from residences wirelessly. Many water heaters are in basements, where cellular connectivity is limited. And while some solutions use Wi-Fi as connectivity, that often requires the installation of a Wi-Fi access point, which can be challenging for the utility to maintain.

The Ara solution, Betcher says, is a hybrid cellular system. Each Ara employs the Nordic nRF9160 multi-mode LTE-M/NB-IoT SiP, as well as a Nordic nRF52840 System-on-Chip (SoC) to provide connectivity from the water heaters to the central server. NB-IoT is an LPWAN technology that allows one device to speak to the next in a daisy chain until transmission reaches a device that has an LTE connection. Apricity uses the LTE-M cellular connectivity with a proprietary mesh backup for areas of poor cellular coverage.

For the Portland deployment, an Ara device is attached to each water heater within the apartment building, and the units can transmit data to each other via LPWAN, as well as send information via an LTE cellular connection, as long as one is available. Once installed, the units draw power directly from the water-heating unit and begin transmitting. If a unit in the basement lacks an LTE connection, it forwards its data regarding temperature and voltage to the next Ara, and so forth, until the information is received by a device with an LTE connection, which then forwards all of the data. The utility sends cellular-based commands to the water heaters to turn off or on, and also views the data received from each unit.

Betcher describes the Ara device as a simple gray box, specifically designed with “no flashy features—you can’t access from your cell phone,” for instance. In fact, once installed, it doesn’t need to be turned on, as it simply begins transmitting data. Once an Ara device is installed, he notes, utilities or their electricians do not need to maintain it. “From a functionality standpoint, the system is just monitoring when the temperature gets too low and turning that heater back on,” says Gabe Ayers, Apricity’s CEO.

Some utilities may wish to use the data not only to turn the water heaters on and off, but also to collect historical data that can help them better understand power usage. An energy company in Hawaii, for instance, is using the technology to view data about each unit’s use, as well as the impact it has on the system as a whole at specific times and days. That utility company, which has asked to remain unnamed, is piloting the solution to provide historical analytics as well. The software captures data regarding water-heater temperature, monitors the power data and uses that information to set up models to shift peak loads.

Apricity says it plans to provide a more intelligent version of the Ara in the future. Currently, the Aras act as switches, sending and receiving data, with no brains for adjusting temperature levels, for example, without a specific request from the utility. “We are in the process of putting together a smart version compliant with CTA 2045,” Betcher says, referring to a technical specification of modular communication interface.

The smart solution would make a water heater interactive so that it can respond to data and automatically adjust its own settings. Pilots of the Ara commenced in September 2019, and the solution is commercially available now. Apricity manufactures the device at its facility in Oregon.