Heat Pump Water Heater 101: Common Heat Pump Water Heater Issues
***DISCLAIMER: PLEASE REFER TO YOUR MANUFACTURER’S INSTALLATION MANUAL FOR INFORMATION REGARDING YOUR SPECIFIC MODEL. IF YOU ARE ATTEMPTING TO SERVICE YOUR OWN HEATER, PLEASE DO SO WITH CAUTION; U.S. WATER HEATING SOLUTIONS, LLC. AND ANY OTHER PARTIES MENTIONED ARE NOT RESPONSIBLE FOR ASSOCIATED LIABILITIES. THIS ARTICLE IS MEANT TO PROVIDE AN INFORMATIVE AND EDUCATIONAL SUMMARY AND DOES NOT SUPERSEDE OFFICIAL WATER HEATER REPAIRS OR MANUFACTURER INFORMATION.
The service calls referenced in this article are predominantly from mid-2023 through September 2025. Future updates to this article will be clearly marked with new dates and model numbers, as applicable.
Heat Pump Water Heaters
Heat pumps have been gaining popularity over the last year, most notably for their increased energy efficiency. For overviews about how heat pump water heaters work and their associated tax incentives, click the buttons below.
With lots of new heat pump installations, there have also been a number installation and operation issues that have led to premature failure. We’ve been compiling information about the most common error codes and issues customers have been experiencing.
Here's What's Different About the Heat Pump Water Heater Design...
Heat pump water heaters generally have less replaceable parts than traditional water heaters because of their design; rather than replacing the main components (i.e., the fan, evaporator, and compressor), most manufacturers will opt to have the entire water heater replaced.
The demand for heat pumps has been been growing since 2023, sometimes making replacement parts difficult to find. In the event that a heat pump unit is under warranty and a) replacement parts are not available or b) the part(s) with issues cannot be replaced, the manufacturer will likely authorize replacement. The following sections of the article will provide an overview of the most common issues our technicians see in the field with heat pump water heaters, as well as some exclusive insights and photos from actual service calls.
Issue #1: Incorrect Installation of Heat Pump Water Heater
As an authorized warranty service provider for several major water heater manufacturers, we receive a number of warranty dispatch service requests to diagnose and attempt to repair heat pump water heaters.
Although some of the components of heat pump water heaters overlap with electric water heaters, they often have more specific installation requirements. One of the largest installation-related differences is that heat pumps can be ducted (or not), requiring some type of air flow and/or additional space. This extra space is the most crucial for the water heater when it is in an installation setting that is not ducted.
(Click image to enlarge)
Issue #2: Loud Heat Pump Water Heater Compressor, Bearings; Heat Pump Water Heater Whistling Noise
Tracing back to 2021, there have been a large number of customer reports about heat pump water heaters being exceptionally noisy (Just Answer, 2021; DoItYourself.com, 2022; Listgarten, 2022), from loud compressors to squealing bearings. Although most of these issues were addressed in 2022-2023, homeowners may still find themselves with loud heat pumps due to purchasing new units that were manufactured in a previous year (e.g., the water heater is brand new in 2025, but it was manufactured in 2022 or 2023) or due to manufacturing defects.
A majority of online discussions about noisy units came from customers using Rheem, Richmond, and Ruud brand heat pump water heaters. These units are described by the manufacturer as having quiet operation, with the ProTerra Hybrid Electric models "featur[ing] sound levels at 45 dBA8—making it easy to relax while enjoying your hot water," where "operation at 45 dBA [is] measured at 6.28 feet using third-party certified testing procedures."
🔑 Key Takeaway: Although it is important to acknowledge that there have previously been documented instances of noisy heat pump units, it is also important for prospective heat pump clients to have realistic expectations about the volume and to consider the installation location inside of their homes. A heat pump water heater is essentially an electric water heater with a special air conditioner on the top; although the actual volume level of the heat pump water heater varies, if air conditioner noise alone is bothersome, it may be worth reconsidering whether switching to heat pump is the right choice, as noise produced by HVAC systems may cause discomfort (Ouis et al., 2025).
What Happened to Real Clients with Noisy Heat Pump Water Heaters?
| Heat Pump Model | Issue | Cause | Solution |
|---|---|---|---|
| PROPH50 T2 RH375-30 | Water heater makes a loud noise when on heat pump/hybrid mode | Regular compressor operation, possibly amplified by sound resonating through the water pipes in the house | N/A |
| HB40 N3-BM | Water heater making a howling sound from the compressor | Regular compressor operation, possibly amplified by dust in the bearings | N/A |
| XE40T10H45U0 | Water heater making a howling sound from the compressor | Issue with capacitor | Replace capacitor |
| 10E50-HP | Water heater making a squealing sound from the compressor | Compressor | Replace water heater |
| HB50 N3 375 | Water heater compressor making slight whining noise | The area of the water heater mechanical room is smaller than 700 square feet and it’s not vented. Nearby rooms are not insulated, meaning there is less buffer for the compressor sound. | Insulating the mechanical room and adjacent rooms |
| HB40 N3 375 | Noisy water heater | Extra foam in the compressor rattling during operation | Removed extra foam |
| HB40 N3-BM | Noisy water heater | Installation issue, improper install | Removed extra foam and then replaced the unit |
| HB40 N3-BM | Noisy water heater compressor | Refrigerant copper lines touching the shroud | Slightly bent it away and put everything back together and cycled unit |
Issue #3: Heat Pump Water Heater Compressor Leaking Oil & Improper Shipping
We have also seen several instances of heat pump water heaters with leaking compressors. In one case, our technician found the unit giving an error code for a faulty upper element. As a friendly reminder, error codes serve as a reference point and not necessarily an exact diagnosis of the issue. After testing the elements, their resistance was within proper range and they were functioning properly, but the compressor was not turning on. Given further observation of the unit, our technician found a hole where oil was leaking out of the compressor (see image slider). A month after this initial service call, the exhaust condensate was blocked and there were compressor errors. Once the exhaust condensate line was cleared, the errors were removed and the unit was functioning properly. Ultimately, after the course of a seven month period, the customer decided to replace their heat pump unit with a regular electric water heater.
Although we were unable to determine the exact cause, one factor to consider is the way the water heater is shipped to the store and then transported to your home. Heat pump water heaters should be transported upright and should not be stacked on top of one another. These shipping instructions are noted on the box to ensure the oil does not seep out and that the compressor and fan are not damaged in transport. However, transportation from the store may be complicated as heat pump water heaters tend to be taller than the average standard water heater because of the fan and compressor affixed to the top. If the units were laid down for transport, it is recommended to place them upright and not run the unit for 48 hours to ensure the oil will stay inside the compressor. In time, the oil will go back into place, but lack of proper oil circulation will prevent the unit from operating properly. As shown in the photos, despite the clearly labeled water heater boxes, some freight services still stack the water heaters improperly.
Issue #4: Heat Pump Mode Not Working, Locking Unit Into Electric Mode as a Temporary Solution
Another common issue we have seen with heat pump water heaters is loss of hot water due to an issue with the heat pump system. While customers await diagnosis or the arrival of certain replacement parts, it is common practice to lock the water heater into electric mode, overriding some of the energy saving features, and enabling the unit to act as a regular electric water heater. In the event that heat pump mode is not working, most models will automatically default into electric mode; this may vary slightly by manufacturer and model. Permitting there are no additional issues with the unit that would prevent electric mode from functioning, the unit can be manually locked the unit into electric mode. However, locking the unit into electric mode is NOT permanent:
- A.O. Smith models' default electric mode setting lasts 3 days, but can be programmed for a maximum of 7 days
- Bradford White models can be locked into electric mode for a minimum of 3 days and maximum of 99 days
- Rheem models can be locked into electric mode for a maximum of 72 hours (3 days), then they will default to Energy Saver Mode
Issue #5: Heat Pump Water Heater Compressor Won't Come On, Wi-Fi Connectivity Issues
The standard system of operations for heat pump water heaters includes: the fan turning on, the compressor turning on, and the water heating up (Bradford White). However, if the compressor does not turn on, the water heater may throw an error code and will not produce hot water. If this occurs and the heat pump model is a wi-fi enabled unit, the unit may be stuck in vacation mode.
Vacation mode is an energy saving mode that allows the unit to store hot water at a lower temperature range for an extended period of time without fully shutting the unit off. This is especially beneficial during the wintertime or vacation season for clients who will not be using their water heater, want to conserve energy, and to avoid the potential surprise loss of hot water upon return. Most manufacturers offer vacation mode settings that can be programmed for a specific amount of time:
- A.O. Smith: 1 day to 99 days or permanently on
- Bradford White: 7 days to 199 days (the minimum default is 7 days)
- Rheem: 2 days to 28 days
We have had customers who went on vacation and upon returning, found their unit was not reaching temperature because it was stuck in vacation mode. It seemed that the change in wi-fi networks and location services shared by the customer's phone triggered the vacation mode issue. Possible solutions include:
- Ensuring your app and phone's operating systems are the most current versions
- Turning off the app permissions to access your location, exiting the app completely, reopening it, and turning off vacation mode
- Delete your home wi-fi network, SSID, and water heater information from the app; then re-add all the information and reboot the water heater
If you continue experiencing this issue after trying the suggestions above, we strongly recommend calling manufacturer's technical support and they can walk you through the steps to resolve the issue.
Other Heat Pump Water Heater Error Codes: Service Call Summaries + Solutions
Error codes are helpful for diagnosing and repairing water heaters. However, it is important to remember that error codes may provide a simple diagnosis and need for single part replacement, or they may be caused by multiple issue(s), requiring careful diagnostics. Here are some examples of error codes our technicians have seen and how the issue(s) were resolved:
Rheem A004 Error Code: Compressor Shutdown
Observed Models: 10E50-HP, HB40 N3-BM
- Unit #1: All temperatures matched ambient temperature. Unit set to electric mode until control board replaced, eliminating the error code (February 2023)
- Unit #2: In addition to the error code, the customer reported that the unit was making a loud, high pitched ringing noise after running hot water in their home for about 10 minutes. The issue was temporarily resolved by replacing AP15095: Thermistor. The customer ultimately chose to downgrade back to a regular electric water heater (September - November 2024)
- Unit #3: The unit's air filter was extremely dirty and the thermistor's readings were out of range. After cleaning the filter and replacing the thermistor, the unit was back online (October 2024, see photos).
- Unit #4: Unit had intermittent A004 error code and capacitor readings were within range. The issue was resolved by replacing the evaporator and thermistors.
Rheem A104 Error Code: Malfunction in Upper Tank Sensor
Observed Model: PRO H40 T2 RH310BM
The A104 error code on this heat pump model will disabled the unit and indicates a malfunction in the upper tank sensor. This error code, however, may be caused by an issue with the upper or lower thermostat, wiring connections, thermistor, or the unit being short circuited (Source: Rheem Manual).
The customer replaced the thermistor and thermostats on their own, but was still unable to resolve the A104 error code. Our technician found the compressor wiring harness was not fully plugged into the control board. After confirming the harness was working properly and not damaged, fully plugging the harness into the control board resolved the error code.
A.O. Smith 084 Error Code: Compressor Shutdown
Observed Models: HPTS-50, HPS-10-50H45DV
The 084 error code on an A.O. Smith brand heat pump indicates the heat pump's compressor is not functioning and recommends receiving technical assistance. After performing diagnostics on site, our technician ordered a replacement control board. The control board replacement resolved the error code.
In another instance, a customer with the same intermittent error code developed into a different outcome. The customer noticed the error code over the course of a month. Our technician checked the air filter and found that it was clean, however there was rust and a blue substance near the corners on the evaporator. The area around the evaporator led to the manufacturer's determination to authorize warranty replacement of the unit. The error code went away after replacing the water heater.
Need Heat Pump Water Heater Repairs, Replacement, or Parts?
Heat Pump Water Heater Repairs in the Midwest + South
Looking for expert Heat Pump Water Heater repair near you? U.S. Water Heating Solutions offers fast, reliable service across the Midwest and South. We currently offer heat pump repair services in approximately 20 states. Our manufacturer-trained technicians specialize in diagnosing and fixing complex hybrid water heaters, ensuring your system runs at peak energy-efficient performance. Don't let a faulty unit impact your savings—call us for trusted heat pump repair and get your hot water back fast!
We are also an authorized warranty service provider for Bradford White and Rheem/Richmond/Ruud, and can provide warranty diagnostics, repairs, and warranty water heater replacement after you receive authorization from the manufacturer.
Our Rheem Heat Pump Service Bins:
We decided to take a hint from our commercial service division and create a mini set of heat pump service bins specific to the Rheem ProTerra Heat Pump models (H-40 and H-50). The service bins were created by our Parts Dept. based on clients' warranty service needs and intend to speed up the repair process. By having parts on hand, we decrease the need to order replacement parts and schedule a return service call to install them.
The service bins include all of the parts (e.g., gaskets, wires, elements) that may need to be replaced. However, there are some larger items such as fan kits and condensers that must be ordered directly from Rheem because they vary by model and their size makes them more prone to damage if we were to stock them on our technicians' service trucks.
Purchase Heat Pump Parts:
U.S. Water Heating Solutions stocks the following common Heat Pump Water Heater Parts:
- AP15095 | Rheem Wired Thermistor
- AP18087 | Rheem Thermistor
- AP20509 | Rheem Heat Pump Thermistor
- SP10869ML | Rheem 240V/4500W Element
- SP20845 | Rheem Thermistor Kit
- SP21160 | Rheem Current Sensing Transformer
- 100108283 | A.O. Smith Heating Element, 240V/4500W, 11in
- 100108455 | A.O. Smith T&P Valve, ¾ in M, 2 in Cav
- 100263911 | A.O. Smith Brass Drain Valve, 2.5 in
Don’t see the heat pump water heater parts you’re looking for or need assistance confirming part compatibility with your water heater? Contact our Parts Dept. for more information.
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