Top 5 Heat Pump Water Heaters for Commercial Retrofits in 2026

Introduction:
Heat pump water heaters (HPWHs) are an increasingly popular choice for commercial retrofit projects due to their high efficiency and potential for significant cost and emissions savings. Unlike conventional electric or gas water heaters, HPWHs use refrigeration technology to absorb ambient heat and transfer it into the water, achieving 3–5 times higher efficiency (COP of 3–5+) than standard heatersaspe.org. This translates into big energy cost reductions – often 60% or more compared to traditional water heating methodsheatwater.com – and helps meet aggressive sustainability goals (switching from gas to heat pumps for water heating can cut a building’s carbon emissions by up to ~91% when paired with clean electricityheatwater.com). Many models are ENERGY STAR® certified, UL-listed for safety, and eligible for generous incentives such as utility rebates or federal programs. For example, one California hotel that retrofitted with heat pump water heaters received $20,000 per unit in rebates, yielding a payback of under 2 yearsaspe.org. The Inflation Reduction Act (IRA) and DOE programs also encourage adoption of efficient electric water heaters – residential ENERGY STAR models qualify for a 30% tax credit up to $2,000, and commercial projects can leverage tax deductions or bonus rebates especially for heat pump and low-GWP refrigerant equipmenttechcleanca.com.

Below we highlight five top heat pump water heater systems well-suited for commercial retrofits. These selections cover all size ranges – from light-commercial 50–80 gallon integrated units up to large modular systems – and prioritize products that are UL listed, ENERGY STAR certified, and incentive-eligible (including units meeting advanced efficiency tiers or using eco-friendly refrigerants). We also note any special installation considerations (voltage, indoor/outdoor configuration, etc.) to help you choose the best fit for your retrofit project.

1. A. O. Smith CHP-120 (119-Gallon Commercial Integrated HPWH)

An A. O. Smith CHP-120 commercial heat pump water heater (front view), a fully-integrated 119 gallon unit with dual fan-coils and backup elements. The CHP-120 delivers about a 4.3 COP efficiency – roughly 4× more efficient than standard electric resistance heaters – by absorbing heat from the ambient air and transferring it into the storage tanksupplyhouse.comaspe.org.

For medium-sized commercial hot water demands, A. O. Smith’s CHP-120 is a leading option. This is a “plug-and-play” 119-gallon heat pump water heater designed specifically for light commercial applications like restaurants, schools, hotels, and office buildingsaspe.orgsupplyhouse.com. The unit integrates a high-efficiency heat pump on top of an insulated storage tank, which simplifies installation and saves space (no separate outdoor heat pump unit or large external tank is needed). The CHP-120’s heat pump operates with an industry-leading Coefficient of Performance around 4.3 under standard conditionssupplyhouse.com, meaning it produces over four units of heat for every unit of electricity consumed. In practice, this level of efficiency can save users on the order of $3,000 per year in energy costs per unit (as reported by a hotel using four CHP-120s)aspe.org. Dual 6 kW electric resistance elements are built-in as backup heaters for times of peak demand, giving a total backup capacity of 12 kW to ensure the unit can meet hot water needs even in heavy usage periodsaspe.org. The system can deliver about 194+ gallons in the first hour and up to 150°F water in heat pump mode (and 180°F in full-electric mode), suitable for commercial sanitation requirementssupplyhouse.com.

Why it’s top-rated: The A. O. Smith CHP-120 is ENERGY STAR® Qualified and optimized for retrofits. It is UL-listed and JA13 (Title 24 California) compliant, indicating it meets strict safety and efficiency standards. Many incentive programs explicitly include this model – for instance, the California TECH initiative and local utilities offer large rebates (as noted, one project received ~$20k per unit)aspe.org. Specifiers also praise the fully-integrated design: the self-contained unit is more compact than piecemeal commercial heat pump systems, easing mechanical room space constraints and simplifying piping and installationaspe.org. According to the lead engineer of a recent hotel retrofit, “the CHP-120’s integrated system makes installation and piping easier… [it] is more compact, so we don’t have to worry about the typical mechanical room space issues”aspe.org. Installation can often be done in a day or two, and only requires standard electric (it can be ordered in 208–240V, single-phase power which is common in commercial buildings) and an adequate air exchange volume in the mechanical area for the heat pump’s air intake/exhaust. In sum, the CHP-120 provides a proven, incentive-ready solution to significantly cut operating costs and emissions in commercial hot water systems – “four times more efficient than a standard electric water heater” as A. O. Smith notesaspe.org, with the reliability of a major manufacturer behind it.

Key Features and Benefits:supplyhouse.comaspe.org

• High Efficiency & ENERGY STAR®: Rated ~4.3 COP and exceeds Energy Star criteria for commercial water heaterssupplyhouse.com. Yields big energy savings (users see ~60–75% reduction in water heating energy use). Qualifies for tax credits and utility rebates.
• 119-Gallon Integrated Tank: Large, insulated storage allows the heat pump to run optimally and store lots of hot water, covering peak loads. First-hour delivery ~194 gallonssupplyhouse.com. Suits restaurants, hotels, multi-family buildings, etc.
• Flexible Operating Modes: Heat Pump mode for max efficiency, Hybrid mode (heat pump + assist from elements), or Electric-only mode for backupsupplyhouse.com. The onboard control with a touchscreen makes it easy to switch modes and monitor status/troubleshootingaspe.orgaspe.org.
• Built-in Backup Elements: Two 6 kW electric elements (12 kW total) kick in during high-demand periodsaspe.orgsupplyhouse.com. Ensures consistent hot water supply even if heat pump alone can’t keep up (for instance, during an unusually long peak in usage or very low ambient air temps).
• Rebate and Retrofit Ready: UL-listed and widely accepted by codes. As a listed electric heat pump with high efficiency, it qualifies for numerous incentive programs (e.g. CA state rebates effectively covering most of the cost in some casesaspe.org). Its compact, integrated form simplifies replacement of existing commercial gas or electric units – no refrigerant handling or external components, just “drop-in” replacement in many boiler rooms.

2. Rheem ProTerra Hybrid (50–80 Gallon Models for Light Commercial Use)

For smaller commercial retrofit applications or multifamily buildings, the Rheem ProTerra Hybrid series is a top contender. Rheem’s ProTerra line (also marketed as Professional Prestige® Hybrid series) offers 50, 65, and 80 gallon heat pump water heaters that are often used in residential and light-commercial settings. The 80-gallon ProTerra is the largest in the line and can serve many small businesses (cafes, office restrooms, etc.) or apartment buildings that have individual water heaters. Like the A.O. Smith unit, the Rheem ProTerra integrates a heat pump on the tank, but it’s generally a slightly smaller form factor (80 gal vs 119 gal) and runs on 208–240V, 30 Amp circuits (with 4.5 kW backup element standard). Despite its “residential” branding, the 80-gallon model is highly efficient (Uniform Energy Factor up to 4.07, Northern Climate Tier 4) and ENERGY STAR certified, making it attractive for commercial retrofits aiming to cut energy usageafsupply.comafsupply.com. In fact, Rheem touts these as “the most efficient water heaters on the market,” capable of saving up to $575 per year in energy costs for users, thanks to the heat pump technologyafsupply.com.

Notable features: Rheem ProTerra units are known for their smart controls and advanced features. They come with built-in Wi-Fi (EcoNet®) connectivity, allowing facility managers to monitor and adjust settings remotely via an appafsupply.com. There are multiple operating modes including Energy Saver (default heat pump mode), High Demand (hybrid mode), electric-only, and vacation modeafsupply.com. The control system can also integrate with demand response programs (CTA-2045 port) to take advantage of off-peak electricity ratesafsupply.com. Additionally, Rheem includes a LeakGuard™ auto-shutoff valve and LeakSense sensor in these models, which is a benefit in commercial settings to prevent water damage – if a leak is detected, the unit can automatically shut off the water inletafsupply.com. This extra peace of mind is coupled with Rheem’s use of durable components (e.g. premium anode rod, stainless elements, washable air filter) to handle the rigors of commercial useafsupply.comafsupply.com.

From an installation perspective, the ProTerra 80 gal unit is a standard tall 240V electric tank footprint (about 24.25 inches diameter, ~74 inches tallsouthernpipe.com). If replacing a similar-sized electric or gas tank, it often fits in the same space. One innovative variant is Rheem’s 120V ProTerra Plug-in model (available in 40–50 gal sizes) which can literally plug into a standard outlet – this lower-capacity unit has become an option for converting small gas heaters to heat pumps without needing a new 240V circuitrheem.com. While 120V models heat more slowly (suitable for smaller loads), it showcases Rheem’s push to make retrofits easier. The mainstream 80-gallon ProTerra, with its 4.0+ UEF efficiency, meets the Northwest Energy Efficiency Alliance (NEEA) Tier 4 specification for cold climates, meaning it can operate in ambient air as low as ~37 °F without resorting to backup resistance heatafsupply.com. This is crucial for commercial installations in unheated spaces or colder regions – the ProTerra will still yield efficient heat pump output through much of the year, maximizing savings.

Why it’s on the top 5 list: Rheem is a trusted name, and the ProTerra hybrids represent state-of-the-art small-commercial HPWH technology. They are ENERGY STAR® rated (UEF 3.70–4.07), so they qualify for virtually all rebate programs and the federal tax creditafsupply.com. Many utilities offer rebates in the $400–$1000 range for these units, and the IRA’s homeowner electrification rebates (in applicable sectors) can also offset costs for small businesses. The ProTerra series emphasizes ease of integration – for example, it’s designed to be a straightforward replacement for standard electric tanks with side water connections and similar footprintsafsupply.com. Noise output is also low (~49 dB), which is important if installed near occupied areas. All in all, Rheem’s ProTerra units are a versatile, efficient choice for commercial retrofits where 50–80 gallon capacity per unit is sufficient. By installing multiple units, larger buildings can also be served (e.g. a multifamily property might put an 80-gal unit in each mechanical closet per floor or per apartment cluster). With smart controls, leak prevention, and a strong efficiency track record, the Rheem ProTerra earns its spot among the top HPWH solutions for commercial projects.

Key Features:afsupply.comafsupply.com

• Sizes & Efficiency: Available in 40, 50, 65, 80 gallon sizes (most commercial use the 80 gal). UEF up to ~4.0 (400% efficiency) and ENERGY STAR certifiedafsupply.com. Operates in cold ambient conditions (down to ~37 °F) thanks to advanced heat pump design, meeting Tier 4 cold-climate requirementsafsupply.com.
• Smart Controls: Integrated Wi-Fi (EcoNet) for remote monitoring/alerts, and demand response readyafsupply.com. Multiple modes (Efficiency, High Demand hybrid, Electric, Vacation) allow tuning performance to the facility’s needsafsupply.com. Automated leak detection/shutoff built-in for protectionafsupply.com.
• Retrofitting Ease: Similar footprint to conventional heaters, with plumbing/electrical connections designed for direct replacementafsupply.com. The 80 gal model runs on 240V/30A; Rheem also offers a unique 120V model for scenarios where adding a 240V circuit is impracticalrheem.com (though 120V recovery is slower). Installation is simple and often does not require refrigerant handling – just place the unit and connect water, power, and condensate drain.
• Quiet, Low-Maintenance Operation: Sound levels around 49 dB, suitable for indoor placement without disturbing occupants. Features like a washable air filter and powered anode help reduce maintenance needsafsupply.com. Long warranties (10-year tank) provide assurance for commercial owners making the investment.

3. Mitsubishi Heat₂O™ (QAHV CO₂ Commercial Hot Water Heat Pump)

Mitsubishi Electric’s Heat₂O commercial CO₂ heat pump water heater outdoor unit. This monoblock unit uses natural CO₂ refrigerant (R-744) with a GWP of 1, enabling high-volume hot water production (up to ~160 °F supply) even in cold climatesmitsubishicomfort.commitsubishicomfort.com.

When it comes to large-scale domestic hot water needs (e.g. hotels, dormitories, hospitals, multifamily buildings), the Mitsubishi Heat₂O system is a cutting-edge solution. Heat₂O (pronounced “Heat-two-O”) is Mitsubishi’s commercial air-to-water heat pump designed specifically for high-demand, central domestic hot water (DHW) applications. At its core is the QAHV CO₂ heat pump technology, which uses carbon dioxide as the refrigerant. CO₂ is an natural refrigerant with ultra-low global warming potential (GWP = 1) and excellent thermodynamic properties for heat pumping. This allows the Heat₂O unit to output very high water temperatures (up to ~160 °F) without supplemental electric heatmitsubishicomfort.com – hot enough for Legionella prevention and for replacing boilers in most commercial hot water systems. Notably, the system remains efficient in any climate, even sub-freezing conditions. CO₂-based heat pumps can extract heat from cold outdoor air (well below 0 °C) and still efficiently heat water, which is why Mitsubishi advertises Heat₂O as suitable “for any size commercial application in any climate”mitsubishicomfort.com. The measured COP can be up to 4.5 in favorable conditionsmitsubishicomfort.com, and performance remains strong year-round due to the transcritical CO₂ cycle optimized in these units.

System configuration: A typical Heat₂O setup has one or more outdoor QAHV heat pump units (each roughly the size of a large VRF HVAC outdoor unit) connected to storage tanks or a piping loop indoors. Each QAHV/Heat₂O unit provides on the order of 40 kW heating capacity (~136,000 BTU/h). Multiple units can be combined (in parallel or series configuration) to scale up for virtually any hot water loadmitsubishicomfort.com. For instance, a large hotel might use 2–4 units to supply all guest bathrooms, laundry, and kitchen DHW needs. Because the Heat₂O is an all-electric, zero-emissions solution, it is often a centerpiece of building decarbonization plans – it eliminates gas combustion and dramatically lowers the carbon footprint of water heating (especially when paired with renewable electricity)mitsubishicomfort.com. Additionally, using CO₂ refrigerant helps future-proof the system against HFC refrigerant phase-outs and may provide extra incentive opportunities. (In California, for example, heat pump systems with refrigerant GWP < 150 can earn bonus rebates on top of normal electrification incentivestechcleanca.com. The CO₂-based Heat₂O easily qualifies.)

Why it stands out: Mitsubishi’s solution is one of the first widely available high-capacity CO₂ heat pump water heaters in the U.S. market, and it has quickly gained a reputation for reliability and performance in commercial retrofits. Early pilot projects and studies (including a BPA feasibility study in the Pacific NW) found that the QAHV-based systems can integrate into existing building DHW systems effectively and cut energy use massively (often replacing or supplementing gas boilers)bpa.govyoutube.com. The Heat₂O units are UL listed and designed to meet U.S. codes. They are typically installed outdoors or on a rooftop – an important consideration is ensuring adequate airflow for the large fan intake/exhaust. Each unit is a monoblock (sealed refrigerant system), so HVAC contractors do not need a refrigerant license to install; they just connect water lines and power. The system is flexible: it can produce hot water up to 160 °F continuouslymitsubishicomfort.com, or it can be configured to charge thermal storage tanks during the day and supply loads during peaks (useful for grid load management). COPs in moderate climates range ~3–4+, and even at very low temperatures the unit will still produce hot water when traditional heat pumps might give up. This makes Heat₂O particularly valuable in cold regions wanting to electrify water heat without sacrificing performance.

Incentives and certifications: Heat₂O is not a standard residential appliance, so it isn’t on the consumer ENERGY STAR list; however, it meets the DOE efficiency criteria for commercial heat pumps and is often eligible for custom incentives. Many utility programs and state initiatives (like Massachusetts’ commercial heat pump rebates or California’s BUILD/Tech programs) provide substantial rebates for CO₂ heat pump water heaters because of their efficiency and climate-friendly refrigerant. The environmental angle is strong: using CO₂ (R-744) refrigerant with GWP=1 aligns with green building standards and future regulations. The units are also often cited as compliant with “natural refrigerant” building incentive programs. In summary, Mitsubishi’s Heat₂O / QAHV brings a powerful, eco-friendly hot water solution to commercial retrofits – one that can handle large loads, operate in freezing conditions, and dramatically reduce both energy bills and emissions. It is a top choice for forward-looking projects such as net-zero hotels, electrified campuses, and multi-family developments seeking to eliminate gas water heating.

Key Advantages:mitsubishicomfort.commitsubishicomfort.com

• Natural Refrigerant (CO₂): Ultra-low GWP (1) and zero ozone depletionmitsubishicomfort.com. No risk of future refrigerant bans. Also enables high-temperature output (up to 149–160 °F without backup) which many synthetic refrigerant heat pumps cannot reachmitsubishicomfort.com.
• High Capacity, Scalable: ~40 kW (136k BTU) per unit; can link multiple units for very large systems. Designed for continuous high-volume hot water – ideal for large commercial DHW loads (hotels, dorms, etc.). “Scalable to any size building” with modular units and storagemitsubishicomfort.com.
• All-Climate Performance: Engineered to operate in cold climates efficiently. Maintains output at low outdoor temps where standard HPWHs struggle. This ensures year-round savings even in places with harsh winters. Mitsubishi reports COP up to ~4.5 in moderate conditionsmitsubishicomfort.com, with reliable operation well below freezing.
• Incentive Eligibility: Qualifies for many decarbonization incentives. For example, additional rebates (e.g. ~$1,500 in CA) are available for air-to-water heat pumps using refrigerant with GWP <150techcleanca.com – Heat₂O’s CO₂ refrigerant easily meets this. Also helps earn LEED or green building credits for refrigerant choice and energy efficiency.
• Sustainability & Future-Proofing: Replaces gas or electric boilers with a zero-emission solutionmitsubishicomfort.com. Reduces on-site combustion, improving safety and indoor air quality. Aligns with cities’ electrification ordinances and climate action plans, effectively “future-proofing” a facility’s hot water system against rising carbon costs or gas bansmitsubishicomfort.com.

4. Nyle Systems Commercial HPWH (Modular and Integrated Solutions)

Nyle “PyroClast™” commercial integrated heat pump water heater – an example of a next-generation, high-capacity HPWH designed for large commercial retrofits. Nyle’s products are made in the USA and use low-GWP refrigerants to deliver hot water at temperatures up to 160–170 °F for demanding applications.

If you’re seeking a flexible, high-performance heat pump water heating system that can be tailored to virtually any commercial retrofit scenario, Nyle Water Heating Systems is a name to know. Nyle is the largest manufacturer of commercial HPWHs in North America, with over 45 years of experience in heat pump technologyheatwater.com. Unlike single-product brands, Nyle offers a portfolio of solutions – from air-source units ranging ~25,000 BTU/h up to 2,000,000 BTU/h in heating capacityheatwater.com, to water-source heat pump water heaters, to complete integrated systems with storage. This means Nyle can cover all size ranges: smaller units (e.g. 25–100 MBH) suitable for apartments or small businesses, mid-size modular systems (200–400 MBH) for mid-sized hotels or dorms, and even huge multi-module setups (1,000+ MBH) for industrial or campus-scale hot water plantsheatwater.com. In practical terms, a single Nyle C-Series heat pump can output anywhere from roughly 50 gallons to over 2,500 gallons of hot water per hour depending on the modelheatwater.com – and multiple units can be combined for even greater output.

Product lines: A few standout offerings include Nyle’s C-Series (air-source HPWH modules that can be ganged together and paired with separate storage tanks – great for retrofitting into existing boiler/tank systems), the e-Series (efficient modular units using eco-friendly refrigerants like R513A), and the new “Alectro” Heat Pump Boiler and “PyroClast” Integrated HPWH. The PyroClast™ is an example of an all-in-one high-capacity unit: it combines a heat pump and storage tank into one package, much like an oversized version of a residential unit but built for commercial duty. PyroClast uses a low-GWP refrigerant (and even won an AHR 2025 Innovation Award finalist spot, signaling its advanced design)heatwater.comheatwater.com. It’s capable of delivering water at sanitizing temperatures (~160+ °F) with strong efficiency. Nyle’s Alectro™ Heat Pump Boiler, on the other hand, is designed to replace or assist hydronic boilers – it can produce 170 °F water even when it’s 30 °F outsideheatwater.com, effectively serving dual purposes of space heating and DHW in some retrofit cases.

Why Nyle for retrofits: The key advantage of Nyle’s lineup is flexibility and engineering support. They emphasize making it “easy to switch to heat pump water heating” and claim their systems can reduce water heating energy costs by over 60% and building emissions by up to ~40% (since water heating typically accounts for ~40% of gas usage in multifamily buildings)heatwater.comheatwater.com. Nyle provides system design/sizing assistance, and their products often can fit into the existing infrastructure. For example, a Nyle C-Series unit might be installed outdoors or in a mechanical room, tying into the existing hot water storage tank and recirculation loop of a building. This modular approach means you don’t necessarily have to replace every component of your current system – you can add heat pump modules alongside existing tanks to progressively transition away from gas boilers, for instance. Furthermore, Nyle’s commercial units are UL certified and designed to meet plumbing code requirements (they work with ASME-rated storage tanks, have appropriate heat exchangers for potable water, etc., as noted in technical briefsbpa.govbpa.gov). The company also highlights that its products are Made in USA and comply with “Build America, Buy America” provisionsheatwater.comheatwater.com, which can be beneficial for public or federally funded retrofit projects seeking to maximize IRA funding (the federal government encourages using domestically made equipment for certain rebate programs).

On the incentive side, Nyle’s high efficiencies mean their units (especially smaller models) can qualify for ENERGY STAR in the appropriate category and thus are eligible for rebates. Many of Nyle’s models have been tested in collaboration with efficiency organizations (for instance, BPA and NEEA have studied Nyle units in multifamily retrofits). In fact, Nyle units are NEEA certified for the Advanced Water Heater Specificationheatwater.comheatwater.com – which in the Northwest is a prerequisite for many utility incentives. This certification attests to performance in cooler climates and overall reliability. Additionally, some of Nyle’s products use refrigerants with GWP < 150 (like R-290 propane or ultra-low GWP blends), which as mentioned can fetch extra rebates in certain states.

Bottom line: Nyle’s commercial HPWH solutions are top-tier for any retrofit that requires scalable capacity and custom configuration. They bring robust performance – e.g., delivering high-temperature water (up to 160–170 °F) for commercial kitchens, laundries, or healthcare facilities – while maintaining strong efficiency. With Nyle, you’re also working with a specialist company that provides end-to-end support (from design to installation to service). Many successful retrofit case studies (hotels, apartments, college dormitories) have utilized Nyle’s systems to slash operating costs and meet decarbonization targets. If your project has unique requirements (space constraints, very large loads, integration with existing systems), Nyle’s range likely has an answer, which is why it secures a spot among the top five.

Highlights:heatwater.comheatwater.com

• Wide Capacity Range: Models from 25,000 BTU/hr (~7 kW) up to 2,000,000 BTU/hr (586 kW) heating capacityheatwater.com. Suitable for small to extremely large facilities. You can mix-and-match modular units to closely meet your building’s load, which maximizes efficiency and minimizes oversizing.
• High Temperature Output: Many Nyle systems can supply 140–160 °F water (some even 180 °F with backup) to satisfy commercial sanitization and retrofit needs. Specialized models (like the Alectro) achieve 170 °F at freezing ambient tempsheatwater.com, enabling replacement of fossil-fuel boilers in most scenarios.
• Low-GWP and Efficient: Focus on eco-friendly refrigerants (e.g. R-513A with GWP ~631, or natural refrigerants in newer designs). High COPs yield >60% energy use reduction for water heatingheatwater.com. Many units meet or exceed ENERGY STAR criteria. NEEA certified for meeting advanced efficiency tiers, which is a testament to performance in real-world installations.
• Made in USA & UL Listed: Built in Maine, USA with UL safety certifications, making them readily approvable by inspectors (meets UL 1995/60335 standards for HVAC equipment). “Buy America” compliance can ease use of federal funds. Strong factory support and parts availability domestically.
• Custom Retrofit Solutions: Nyle’s engineering team often assists in designing the system – whether it’s a drop-in tank replacement unit like PyroClast or a split heat pump feeding existing tanks. This reduces risk in retrofits. Their systems can often utilize existing electrical infrastructure (multiple small units on 208–230V single phase or larger units on 480V 3-phase, depending on model). This flexibility simplifies the upgrade from gas or direct electric systems to heat pumps.

5. Intellihot Electron iE1 (Tankless CO₂ Heat Pump Water Heater)

Rounding out our top five is a truly innovative entrant: the Intellihot Electron iE1, which is billed as the world’s first tankless heat pump water heaterintellihot.com. Intellihot is known for commercial tankless (on-demand) water heaters, and with the Electron series, they have combined tankless design with heat pump technology. The iE1 is an all-electric, CO₂ refrigerant heat pump that produces hot water on demand, rather than heating and storing a large volume. It incorporates a small thermal storage battery (containing a volume of recirculating heat-transfer fluid and a heat exchanger) which the heat pump keeps charged with heat; when hot water is needed, that stored energy is instantly transferred to the potable water via a heat exchanger as it flows – delivering endless hot water without a big tankintellihot.comintellihot.com. In effect, this design merges the efficiency of a heat pump with the space-saving convenience of a tankless system.

Key specs: The Intellihot iE1 has a maximum heating output of ~90,000 BTU/h (~26 kW) which is comparable to a mid-sized tankless gas heaterintellihot.com. Its heat pump uses CO₂ (R-744) refrigerant (GWP = 1) and can achieve a COP up to ~4.9 at moderate conditionsintellihot.com – an extremely high efficiency rating. Importantly, it can produce water up to 170 °F if neededintellihot.com, which is higher than most standard heat pump heaters and sufficient for commercial hot water loop disinfection cycles. The unit itself is relatively compact and can be wall-mounted. It is offered in multiple electrical configurations to adapt to site power: for example, an iE1-Std model draws only ~20 Amps at 208–240V (heat pump only, no resistance element), whereas iE1-Mid and iE1-Max models include one or two resistive elements for boost and require 60A or 90A breakers respectivelyintellihot.com. Even the largest model is a fraction of the power of equivalently sized electric tankless heaters, thanks to the heat pump’s contribution.

Unique benefits in retrofits: The tankless design means no large storage tank is required – a huge advantage when mechanical room space is tight or when existing old tanks cannot be easily replaced due to access constraints. Intellihot specifically markets the iE1 for scenarios like restaurants, hotels, multifamily buildings, etc., where it can free up space and eliminate thermal losses from stored hot water. Multiple iE1 units can be cascaded wirelessly (via Bluetooth) to function as a unified system for higher flow demandsintellihot.com. For instance, two or three iE1 units can work in tandem to serve a larger domestic hot water system, communicating to stage on/off as needed – all without running control wires between them. This wireless cascading works up to ~50 ft distanceintellihot.com, which covers most side-by-side installations. The iE1 is designed for indoor or outdoor installation (outdoor installs are feasible since the unit is sealed and weather-resistant, though in very cold climates it’s usually placed indoors or in an enclosure)intellihot.comintellihot.com.

One of Intellihot’s strong claims is that the tankless heat pump design mitigates Legionella risk because there is no stratified warm tank of water sitting around – water is heated on demand and flows at high velocity through the heat exchanger, which helps scour biofilmintellihot.com. This can appeal to healthcare and hospitality retrofits where Legionella compliance is important. Additionally, the iE1 includes smart features like built-in cellular connectivity for remote monitoring and software updates (Intellihot provides a 24/7 monitoring service)intellihot.com. It’s also grid-friendly, with the ability to shift when it draws power (charging its thermal battery during off-peak times) and a CTA-2045 demand response portintellihot.com.

Recognition and use cases: The Intellihot Electron series has garnered industry awards (e.g. Edison Award 2024)intellihot.com, highlighting its potential to disrupt how we heat water in commercial settings. A notable early adopter is IKEA, which installed two iE1 units at a store in Maryland as part of its energy efficiency initiatives – proving the concept in a real retail environmentintellihot.comintellihot.com. In that application, the iE1s provided endless hot water for the store’s restrooms and cafeteria, in line with IKEA’s move to electrify and decarbonize. The feedback so far indicates that these units can reliably replace gas tankless or electric tank systems with substantial energy savings and no loss of performance. Because the iE1 uses CO₂ refrigerant and is very efficient, it is eligible for similar incentives as the Mitsubishi Heat2O: many custom commercial rebate programs or pilot incentives will apply (and its GWP=1 refrigerant again meets stringent green criteria). It is UL listed and expected to meet relevant plumbing standards (Intellihot notes it will be ASSE 1082 compliant, meaning it can deliver hot water without requiring a mixing valve under certain conditions safely)intellihot.com.

In summary, the Intellihot iE1 is a future-forward solution perfect for commercial retrofits where space is at a premium or traditional heat pump water heaters don’t fit well. By eliminating the storage tank and using a natural refrigerant, it offers a combination of sustainability and practicality. While relatively new, it’s a top pick for innovative projects, and thus earns its place in the top five.

Key Features:intellihot.comintellihot.com

• Tankless, On-Demand Design: No bulky tank – uses a thermal battery to supply on-demand hot water, up to ~4 GPM per unit continuous. This saves space and eliminates standby heat losses. Multiple units can be installed to increase flow capacity, communicating wirelessly for load sharing.
• CO₂ Heat Pump Efficiency: COP up to ~4.9 (490% efficient) under normal conditionsintellihot.com. Uses CO₂ refrigerant (GWP=1), giving it excellent cold-weather performance and making it eco-friendly. Capable of 170 °F outlet temp for sanitation or baseboard heating backupintellihot.com.
• Flexible Power Options: Models can run with as low as a 20A breaker (heat-pump-only mode) or up to a 90A breaker with resistance boost elementsintellihot.com. This means an iE1 can be configured for sites with limited electrical capacity (just run in heat pump mode for max efficiency), or faster recovery if ample power is available (enable the resistance elements for quick charging of the thermal battery).
• Smart Monitoring & Safe Operation: Includes IoT connectivity – 24/7 cloud monitoring and OTA software updates to optimize performanceintellihot.com. Integrated leak detection (distinguishes glycol vs water leaks) and self-protection featuresintellihot.com. The design inherently reduces Legionella risk (no stored warm water) and is compliant with safety standards for on-demand heatersintellihot.comintellihot.com.
• Indoor/Outdoor Installation: Can be placed outdoors (cold climate installs will require freeze protection for external piping, similar to any tankless) or indoors – the unit is sealed and relatively quiet. Airflow requirement ~3,500 CFM; the iE1 draws air from the front and exhausts out the top, so needs sufficient clearanceintellihot.comintellihot.com. No combustion venting needed, of course, simplifying replacement of gas units.

---

Conclusion:
Upgrading to any of these top-tier commercial heat pump water heaters can dramatically improve a facility’s energy efficiency and sustainability profile. Whether you need a turnkey integrated unit (like the A.O. Smith or Rheem for simpler installs), a high-capacity CO₂ system for a large building (Mitsubishi Heat₂O), a modular/custom solution (Nyle’s broad range), or an innovative tankless approach (Intellihot iE1), there’s a heat pump water heater on this list to suit all sizes and project requirements. All five options highlighted are UL-listed for safety, and most carry ENERGY STAR or equivalent efficiency credentials, making them eligible for various rebates and incentives that can significantly offset initial costs. By prioritizing heat pump technology – and especially models with advanced features like low-GWP refrigerants and smart controls – commercial retrofits can not only save money but also contribute to broader goals like carbon reduction and compliance with emerging building codes. The initial investment in a heat pump water heater is often recouped quickly through energy savings (often in just a few years), and the availability of IRA/DOE funding, utility rebates, and tax credits in 2025 makes it an ideal time to make the switch. In short, these “top 5” HPWH systems represent the best of modern water heating: efficient, reliable, incentive-ready solutions that prepare your commercial facility for a greener, more cost-effective future.

Sources:

1. A. O. Smith CHP-120 Fully Integrated Commercial Heat Pump – Product Description and Case Studysupplyhouse.comaspe.orgaspe.org
2. Rheem ProTerra Hybrid Heat Pump Water Heater – Product Specificationsafsupply.comafsupply.com
3. Mitsubishi Electric Heat₂O Commercial CO₂ HPWH – Product Brochuremitsubishicomfort.commitsubishicomfort.com
4. Nyle Commercial HPWH Systems – Manufacturer Website and Dataheatwater.comheatwater.com
5. Intellihot Electron iE1 Tankless HPWH – Product Info and News Releaseintellihot.comintellihot.com