Understanding Rheem Hybrid Electric Heat Pump Water Heater Operating Modes
Understanding Rheem Hybrid Electric Heat Pump Water Heater Operating Modes
May 29, 2025
When it comes to water heating, striking the balance between efficiency and performance is crucial. Rheem® Hybrid Electric Heat Pump Water Heaters (HPWH) were designed for this very reason, offering five distinct operating modes to adapt to household hot water needs while providing maximum efficiency and cost savings.
Let’s explore how each mode works, when each should be used, and the other external factors that homeowners need to consider.
Energy Saver Mode (Default Mode)
Energy Saver mode is the default mode for the hybrid electric HPWH. This mode adjusts to hot water demands while optimizing energy savings. Energy Saver mode uses both heat pump technology and the upper electric element to optimize hot water production and energy savings. The system prioritizes heat pump technology, only activating the upper electric element when necessary to quickly reheat the top portion of the tank. This approach maximizes efficiency without sacrificing comfort, making it ideal for normal daily use.
Under certain circumstances Energy Saver mode may not provide enough hot water. During high usage periods and winter months in select regions, switching to High Demand Mode may be necessary.
High Demand Mode
In High Demand mode, the unit’s heat pump operates simultaneously with either the upper or lower electric elements to heat the entire tank faster and more evenly. The heat pump activates when lower tank water drops below threshold temperature. Should that temperature drop significantly below the threshold (due to cold inlet water or very high hot water demand), the lower electric element activates as well. The simultaneous operation of heat pump and lower element heats the inlet water entering the lower portion of the tank quickly. When water in the upper tank water drops below threshold, the upper element activates, and lower element turns off.
Heat Pump Mode
Heat Pump mode is ideal for periods of low hot water demand. It prioritizes energy savings over hot water production. In this mode, the electric elements remain off, reducing electricity use significantly. However, water heating is slower, which can take anywhere from 2 to 10 hours to fully recover depending on the ambient air and incoming water temperatures. This setting is ideal for households with consistent, low hot water demand and is best used in moderate to warm climates.
Electric Mode
Electric Mode functions just like a traditional electric water heater. Both the upper and lower heating elements alternate to heat the water, while the heat pump is disabled. Rheem recommends Electric Mode for use only when ambient temperatures drop below 37°F, or as a back-up if the heat pump is unavailable. Notably, the unit will automatically revert to the default Energy Saver Mode after 72 hours to prevent unnecessary energy consumption.
Away/Vacation Mode
When you’re away for an extended period (2-28 days), Away/Vacation Mode is your go-to. Constantly maintaining a tank full of hot water that no one is there to use consumes unnecessary energy! Away/Vacation mode reduces the temperature set point to 65°F, activating the heat pump only if the lower tank water temperature falls below 50°F. This helps minimize energy use while keeping the water warm enough for faster recovery when you return. With the convenience of the EcoNet® app, switching back to a normal operating mode can be done remotely, ensuring that hot shower will be ready and waiting when you return.
Other Factors That Affect Performance
As discussed in the description of each operating mode, external factors significantly impact the performance of your Hybrid Electric HPWH. Inlet water temperature plays a major role: colder incoming water requires more energy and time to heat. Ambient air temperature is equally important, as the heat pump extracts heat energy from the surrounding air. In colder environments (below 37°F), the heat pump’s efficiency decreases, making supplemental electric heating necessary. Finally, household hot water demand patterns will influence recovery times and energy usage. Higher demand periods may require using High Demand to maintain adequate hot water supply.
US 9 Zone Map – Ground Water Tempurature in °F
Hybrid Electric Heat Pump Water Heater – Number of Showers by Ground Water Zone
Choosing the Right Mode
Rheem’s hybrid technology and 5 operating modes offer homeowners flexibility to adjust their water heater’s operation based on changing needs and seasonal conditions. Whether it’s saving on energy bills with Heat Pump Mode, ensuring plenty of hot water during the holidays with High Demand Mode, or conserving energy while away, Rheem puts you in control.
It’s important to schedule annual professional maintenance for your water heater to ensure its longevity and efficiency. Find a Rheem plumber or contractor near you to help with installation and maintenance.
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