Both are heat pump water heaters. The HPTS-66-2 is more efficient (UEF 3.70 vs 3.34). The NHP65 saves $45/year to operate. All figures from published specs and EIA energy prices. UEF measures lab efficiency under DOE test conditions. Annual cost uses that rating plus national average energy prices. Different draw patterns, local rates, and standby losses can cause the rankings to diverge.
Performance
| Spec | HPTS-66-2 A. O. Smith · Heat Pump | NHP65 Noritz · Heat Pump |
|---|---|---|
| UEF | 3.70Difference: 0.36 | 3.34 |
| Capacity | 67 galDifference: 10 gal | 57 gal |
| First Hour Rating | 82 galDifference: 12 gal | 70 gal |
| kW Input | 4.50 kWidentical | |
The HPTS-66-2 leads on efficiency. But does it fit? Sizing guide
Physical dimensions
| Dimension | HPTS-66-2 | NHP65 |
|---|---|---|
| Height | 61.50"Difference: 2.30" | 63.80" |
| Width | 26.50"Difference: 1.50" | 28" |
| Depth | 26.50"Difference: 1.50" | 28" |
The NHP65 is taller. Fit checked. Now the operating cost.
Operating cost
| Cost | HPTS-66-2 | NHP65 |
|---|---|---|
| Annual Operating Cost | $213/yr | $168/yrDifference: $45/yr |
| 10-Year Operating Cost | $2,130 | $1,680Difference: $450 |
| Annual Energy | 1,233 kWh | 974 kWhDifference: 259 kWh |
10-year difference: $450 in favor of the NHP65, at current US average energy rates. Actual savings depend on local rates and usage patterns.
Costs vary by state. The HPTS-66-2 ranges from $136/yr (ND) to $513/yr (HI). The NHP65 ranges from $107/yr (ND) to $405/yr (HI).
$45/yr separates them. Install requirements determine the upfront gap. Installation accessories
Installation requirements
| Requirement | HPTS-66-2 | NHP65 |
|---|---|---|
| Voltage | 240Videntical | |
| Amperage | 22ADifference: 1A | 23A |
| Breaker | 30Aidentical | |
| Condensate Drain | Yesidentical | |
Same electrical requirements. Swapping between these units should not require electrical changes.
Warranty
| Coverage | HPTS-66-2 | NHP65 |
|---|---|---|
| Tank | 10 yridentical | |
| Parts | — | 10 yr |
| Labor | — | 1 yr |
Features
| Feature | HPTS-66-2 | NHP65 |
|---|---|---|
| Wi-Fi / Smart | Yes | No |
| Noise Level | 45 dBDifference: 9 dB | 54 dB |
| Refrigerant | R-134aidentical | |
Decision split
Pick this one if...
A. O. Smith HPTS-66-2
- Your ceiling or space is under 63.80"
- You need quiet operation (45 dB vs 54 dB)
- You want smart home / Wi-Fi control
- Peak efficiency is the priority (UEF 3.70)
Pick this one if...
Noritz NHP65
- Minimizing energy cost matters (saves $45/yr)
Neither if...
- You have no floor drain and cannot add condensate handling
- Your home only has 120V service and you cannot upgrade the panel
- Your install space is under 700 sq ft of open air
Common accessories for this type of installation.
Common install considerations for heat pump units
What is required depends on your existing installation, local code, and installer preference.
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Related
Sources. ENERGY STAR, manufacturer spec sheets, EIA average energy prices.Methodology