Model specs
HPTA-40-2
A. O. Smith / 36-Gallon Heat Pump Water Heater
Lower running cost than standard electric, but height, 240V, and condensate still decide fit.
UEF3.6Certified efficiency
First hour55 galHot water delivery
Height66"Primary fit constraint
Running cost~$157/yrU.S. average electricity
Estimated annual savings: $459 compared to a standard standard electric tank. Based on U.S. average energy prices. See all heat pump models
HPTA-40-2 operating cost
This unit saves roughly $459 every year compared to the standard electric tank it replaces
HPTA-40-2
$157/yr
Std tank (0.92 UEF)
$616/yr
~2.6year payback
At $459/yr in savings, the upfront premium pays for itself in about 2.6 years. Over 10 years: roughly $3,390 in net savings.
Your state changes the math. Annual cost ranges from ~$98/yr (ND) to ~$359/yr (HI).
U.S. avg electricity: 17.4¢/kWh (EIA, Jan 2026). The federal tax credit of up to $2,000 under IRA Section 25C expired December 31, 2025. State and utility rebates may still apply.
Your state changes the cost. Ranges from $98/yr to $359/yr depending on your state's electricity rate.
HPTA-40-2 cost by state
Ranges from $98/yr to $359/yr depending on your state's electricity rate. U.S. average: $157/yr.
Alabama$145/yr16.1¢/kWhAlaska$230/yr25.5¢/kWhArizona$141/yr15.6¢/kWhArkansas$111/yr12.3¢/kWhCalifornia$273/yr30.3¢/kWhColorado$148/yr16.4¢/kWhConnecticut$255/yr28.3¢/kWhDelaware$149/yr16.5¢/kWhDistrict of Columbia$214/yr23.7¢/kWhFlorida$144/yr15.9¢/kWhGeorgia$130/yr14.5¢/kWhHawaii$359/yr39.8¢/kWhIdaho$109/yr12.1¢/kWhIllinois$148/yr16.4¢/kWhIndiana$146/yr16.2¢/kWhIowa$116/yr12.8¢/kWhKansas$129/yr14.3¢/kWhKentucky$129/yr14.3¢/kWhLouisiana$112/yr12.5¢/kWhMaine$277/yr30.7¢/kWhMaryland$186/yr20.6¢/kWhMassachusetts$281/yr31.2¢/kWhMichigan$176/yr19.5¢/kWhMinnesota$135/yr15.0¢/kWhMississippi$128/yr14.2¢/kWhMissouri$106/yr11.8¢/kWhMontana$116/yr12.9¢/kWhNebraska$106/yr11.8¢/kWhNevada$126/yr14.0¢/kWhNew Hampshire$237/yr26.3¢/kWhNew Jersey$209/yr23.1¢/kWhNew Mexico$133/yr14.7¢/kWhNew York$256/yr28.4¢/kWhNorth Carolina$123/yr13.7¢/kWhNorth Dakota$98/yr10.9¢/kWhOhio$159/yr17.6¢/kWhOklahoma$114/yr12.6¢/kWhOregon$132/yr14.7¢/kWhPennsylvania$182/yr20.2¢/kWhRhode Island$272/yr30.1¢/kWhSouth Carolina$139/yr15.4¢/kWhSouth Dakota$123/yr13.6¢/kWhTennessee$118/yr13.1¢/kWhTexas$142/yr15.7¢/kWhUtah$116/yr12.9¢/kWhVermont$210/yr23.3¢/kWhVirginia$143/yr15.9¢/kWhWashington$125/yr13.8¢/kWhWest Virginia$133/yr14.8¢/kWhWisconsin$164/yr18.2¢/kWhWyoming$116/yr12.8¢/kWh
Based on 902 kWh/yr (ENERGY STAR rated) at each state's residential electricity rate (EIA, Jan 2026). Click a state for rebates, code requirements, and model rankings.
HPTA-40-2 in the 40-gallon heat pump class: #2 of 2 on efficiency.
Should this be on your shortlist?
Best for
top-tier efficiency, compact height, 10-year tank warranty (class-leading)
- Why it makes shortlists: solid mid-class efficiency (#2 of 2)
Shortlist alternatives in 40-gallon heat pump:
Rheem PROPH40 T2 RH400-30UEF 3.83 · 62.3" tallWithin A. O. Smith's 40-gallon heat pump lineup, this page fills a specific role.
Where it sits in the A. O. Smith lineup
- On efficiency, A. O. Smith HPTA-80-2 sits higher in A. O. Smith's 40-gallon heat pump lineup at 3.88 UEF versus 3.60 here.
- For heavier simultaneous demand, A. O. Smith HPTA-80-2 is higher at 95 first-hour gallons versus 55 here.
- If cabinet height is the constraint, A. O. Smith HPTA-66-2 is shorter at 61.0 inches versus 66.0 here.
The bill may work. Now check what actually changes on install day before you let the shortlist settle.
Switching to the HPTA-40-2
From a standard electric tank
Same voltage (240V). Verify breaker size matches unit requirements (30A typical).
Taller unit (66"). Measure overhead clearance.
Condensate drain needed. Floor drain or condensate pump.
Air space needed around the unit for heat exchange.
Fewest install changes of any upgrade path. Scope depends on existing wiring, clearances, and condensate routing.
From a gas tank
New 240V/30A circuit required. Hire an electrician.
Gas line capped. No more gas bill for hot water.
Existing flue/vent can be removed.
Condensate drain needed.
Two trades needed (plumber + electrician).
From an older heat pump
Same electrical. Same condensate drain.
Check height. This unit is 66" tall.
Standard water connections.
Similar installation profile. Verify dimensions, clearances, and condensate routing match your existing setup.
Height, electrical service, condensate, and noise. These are the four things that determine whether a heat pump fits your space and your quote.
HPTA-40-2 installation specifications
Dimensions
Height66 in
Width20 in
Electrical
Voltage240V
Amperage22A
Heat Pump
Min ambient temp37°F
RefrigerantR-134a
Noise49 dBA
Safety and installation warnings
These warnings apply to this water heater type. Always follow the manufacturer's installation instructions and local building codes. Hire a licensed professional for installation.
T&P relief valve. Every tank-type water heater has a temperature and pressure relief (T&P) valve. This is a critical safety device that prevents tank rupture by releasing water if temperature exceeds 210°F or pressure exceeds 150 PSI. The discharge pipe must run to within 6 inches of the floor or to an exterior drain. Never cap or plug the T&P valve. Test it annually.
Scald prevention. The recommended maximum water temperature is 120°F to prevent scalding. Higher temperatures (130-140°F) reduce Legionella bacteria risk but require a thermostatic mixing valve at the outlet to deliver safe temperatures at fixtures. Some jurisdictions require mixing valves when the tank is set above 120°F.
Cold-climate performance. Below 37°F ambient air temperature, the heat pump compressor shuts off and the unit falls back to electric resistance heating at much lower efficiency. The rated UEF assumes DOE test conditions (67°F ambient, 58°F inlet water). In cold climates or unconditioned spaces (garages, unfinished basements), actual annual efficiency will be lower than the rated UEF, and energy costs will be higher than the estimates shown above.
Cold exhaust air. Heat pump water heaters extract heat from surrounding air and exhaust cold, dehumidified air. Do not install in a space that is already difficult to heat. The unit will lower the room temperature by several degrees, which may increase HVAC costs or reduce heat pump efficiency in winter.
Common install considerations for heat pump units
What is required depends on your existing installation, local code, and installer preference.
Warranty
Coverage
Tank10 yr
Class rankings: 40-gallon heat pump water heaters
Rankings
Efficiency (UEF) higher is better
#2Runner-UpEfficiency · 2 models tested
1
Rheem PROPH40 T2 RH4...
2
A. O. Smith HPTA-40-2
Height shortest to tallest
#2Runner-UpCompactness · 2 models tested
1
Rheem PROPH40 T2 RH4...
2
A. O. Smith HPTA-40-2
First Hour Rating higher means more hot water
#2Runner-UpHot Water Delivery · 2 models tested
1
Rheem PROPH40 T2 RH4...
2
A. O. Smith HPTA-40-2
Starting May 2029, new federal standards require heat pump technology for electric water heaters over 35 gallons. Electric tanks 35 gal and under can still use resistance elements. Every heat pump on this list already exceeds the future standard. Read the full DOE 2029 analysis
Common questions about the A. O. Smith HPTA-40-2
From manufacturer specs, EIA energy data, and DOE regulations.
How much does the HPTA-40-2 cost to run per year?
~$157/yr at the U.S. average electricity rate. That is roughly $459/yr less than a standard electric tank.
How much hot water does the HPTA-40-2 deliver?
55 gallons in the first hour from a 36-gallon tank. Suitable for a household of 1 to 3 people at medium draw.
Will the HPTA-40-2 fit in my space?
66" tall, 20" wide. Measure your space including clearances before ordering.
Does the HPTA-40-2 work in cold climates?
The heat pump operates down to 37°F ambient temperature. Below that, it switches to standard electric resistance mode, losing the efficiency advantage. In cold climates, install inside the heated building envelope, not in an unheated garage.
What warranty does the HPTA-40-2 come with?
10-year tank warranty. Register with A. O. Smith after installation to activate full coverage.
Is the HPTA-40-2 eligible for rebates?
ENERGY STAR certified heat pump water heater. The federal tax credit (IRA Section 25C, up to $2,000) expired December 31, 2025. State and utility rebates may still apply depending on your location.
Is this unit future-proof under the 2029 DOE standards?
Yes. Starting May 2029, electric water heaters over 35 gallons must use heat pump technology. This unit already exceeds that standard.
Full specifications
| Performance | |
| UEF | 3.6 |
|---|---|
| First Hour Rating | 55 gal |
| kW Input | 4.5 kW |
| Draw Pattern | Medium |
| Est. Annual Energy | 902 kWh/yr |
| Capacity | |
| Storage Volume | 36 gal |
| Physical | |
| Height | 66 in |
| Width | 20 in |
| Electrical | |
| Voltage | 240 V |
| Amperage | 22 A |
| Heat Pump | |
| Type | 240 Volt Integrated HPWH |
| Min Ambient | 37 °F |
| Refrigerant | R-134a |
| Sound Level | 49 dBA |
| Warranty | |
| Tank | 10 yr |
| Certifications | |
| ENERGY STAR | Certified |
| Markets | United States |
Keep the route moving
Other A. O. Smith models and the full heat pump guide, if this one isn't the right fit.
Sources. ENERGY STAR, Retailer listing. Specs last verified 2026-03-17.Methodology
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