Heat Pump Water Heaters
What Every Homeowner and Inspector Should Know
Heat Pump Water Heaters: What Every Homeowner and Inspector Should Know
By John C. Hansen, LEED AP
Licensed Home Inspector, Illinois
This year on Heat Pump Water Heater Day, I found myself reflecting on how much these systems have evolved, and how many of us might still treat them like their older, electric-resistance cousins. They may share the same basic goal of providing a ready supply of hot water, but their maintenance and operating behavior tell a very different story.
1. Anode Rods: The Overlooked Guardian
Like traditional water heaters, heat pump water heaters (HPWHs) rely on a sacrificial anode rod to protect the tank from corrosion. What’s different is how accessible that anode is.
Because the compressor and fan assembly sit on top, the anode is often tucked beneath tight clearances that make inspection or replacement challenging. In some models, the bolt head sits flush against a panel or wall, requiring a segmented replacement anode or creative maneuvering to reach it.
Recommended check: Every 2–3 years, inspect the anode or at least plan for its eventual replacement.
Inspector’s tip: If you can’t access it easily, note that limitation in your report.
Homeowner tip: Ask your installer whether a segmented anode rod can be used for future servicing.
2. Condensate: The Hidden By-Product of Efficiency
A heat pump water heater doesn’t just heat water it also dehumidifies the surrounding air. The by-product of that process is condensate, which must be drained away through a small line, similar to an air conditioner’s condensate drain.
When that line clogs, you may see moisture pooling under the unit or hear the fan struggling. It’s not unusual for dust, microbial buildup, or small kinks in the tubing to cause a backup.
Best practice: Flush or blow out the condensate drain once a year.
Tools: Compressed air, a wet/dry vacuum, or a short burst from a small air compressor.
Inspector’s note: Condensate discharge should terminate at an approved drain point—never onto the floor.
Homeowner’s caution: Some homes may also require a condensate neutralizer if the drain terminates on concrete or near metal piping.
3. Air Filter Cleaning: The Forgotten Task
This is where many HPWH owners, and even a few inspectors, get caught off guard.
The air intake filter on top of the heat pump unit prevents dust from coating the evaporator coil. When airflow is restricted, the unit’s efficiency drops, and recovery time lengthens.
In practice, this filter should be checked and cleaned about every three months, which is roughly the same interval recommended for forced-air furnace filters. The concept is identical: unrestricted airflow keeps the system efficient and prevents dirt from collecting on the heat-exchange surface.
Manufacturer guidance: Rheem, A. O. Smith, and Bradford White all suggest cleaning the filter every few months or more often in dusty environments.
Inspector’s note: Dirty filters are often visible from the top grille, an easy observation worth noting.
Homeowner reminder: Cleaning takes only a minute and usually requires no tools. A quick rinse and dry is enough.
4. Tank Flushing: Still Necessary
Despite their high efficiency, HPWHs are not immune to mineral buildup. The heat pump may mask the effects of sediment accumulation, but the tank still needs periodic flushing.
Draining the tank annually helps preserve capacity and performance, especially in areas with hard water.
5. A Word on Energy and Cost
Discussions of “efficiency” can be misleading without context.
A heat pump water heater is certainly more efficient than a traditional electric-resistance model, but most homeowners in the Chicago region are comparing it to gas-fired water heaters—either standard atmospheric-vent units or higher-efficiency sealed-combustion types.
The energy picture therefore shifts from efficiency to cost: electricity rates, natural-gas pricing, and household demand all play a role in determining actual savings.
While the technology itself is capable of impressive performance, the more practical conversation for most households centers on maintenance, reliability, and lifespan, an areas where all water heaters, regardless of fuel type, benefit from attention and care.
Closing Thought
The difference between water-heating technologies isn’t just a matter of fuel, it’s a reflection of how we maintain them. Where one system relies on simple combustion, another depends on air movement and coil efficiency. Each rewards regular attention.
Postscript: Yes, There Really Is a Heat Pump Water Heater Day
If this is news to you, you’re not alone. Heat Pump Water Heater Day is an official awareness event organized by the Advanced Water Heating Initiative (AWHI) to promote education about this fast-growing technology.
The date this year was Thursday, October 23. The event brought together manufacturers, builders, installers, utilities, and energy professionals, but home inspectors haven’t yet joined the conversation in large numbers. Is this because most of our inspections are on homes that use natural gas for water heating?