DHW Efficiency & Official EnergyGuide Tank Labels
In addition to space heating and cooling, an extra feature of the Chiltrix award-winning and record-setting air-to-water heat pumps is high-efficiency domestic water heating. This leverages the high COP of the Chiltrix heat pump to deliver water heating with up to more than five times higher efficiency than a standard electric water heater — providing up to 70-80% energy savings on annual water heating.
*Chiltrix domestic water heating systems lead the US water heater industry in First-Hour Ratings and Uniform Energy Factor (UEF) efficiency ratings.


Chiltrix has officially set ANOTHER WORLD RECORD.
This time, it’s for water heating. Leading the way is the Hitzewelle CX50DHW105RIDNR system (using a 99-gallon tank with a CX50), which achieved an unprecedented UEF of 4.95 — the highest efficiency rating among all residential water heaters — along with a First-Hour Rating of 133 gallons. Even higher performance is possible with the CX65, but it is too powerful to be rated as a residential water heater (it achieves UEF 5.48 under the same lab test procedure). DHW packages using CX65 are classified as commercial water heaters.
Chiltrix Domestic Water Heating Official ENERGYGUIDE Tank Labels
We Also Broke The Dept. of Energy Rating System
Off the scale. Literally. Several Chiltrix configurations have such low Official DOE Estimated Yearly Energy Costs that they are off the scale of the standard DOE EnergyGuide label template. You can compare Chiltrix ratings against every other certified water heater in the U.S. Department of Energy Compliance Certification Database where you can see how Chiltrix compares to all others in First-Hour delivery and Uniform Energy Factor (UEF).
*Chiltrix beats all residential water heaters in UEF, and beats all residential water heaters under 119 gallons in First-Hour ratings.
Click the Chiltrix Model Number Below to see the Official U.S. Government EnergyGuide label.
EnergyGuide Labels per Package Model
| Model Number | First Hour | UEF | System Configuration |
|---|---|---|---|
| CX35DHW80NR | 87 Gallons | 3.31 | CX35 with DHW80 Tank, No Backup Element / 71 gal. Tank |
| CX50DHW80NR | 88 Gallons | 3.49 | CX50 with DHW80 Tank, No Backup Element / 71 gal. Tank |
| CX35DHW105NR | 80 Gallons | 3.75 | CX35 with DHW105 Tank, No Backup Element / 99 gal. Tank |
| CX50DHW105NR | 93 Gallons | 3.69 | CX50 with DHW105 Tank, No Backup Element / 99 gal. Tank |
| CX35DHW105RIDNR | 101 Gallons | 4.95 | CX35 with DHW105 Tank w/ Reverse Indirect, No Backup Element / 99 gal. Tank |
| CX50DHW105RIDNR | 133 Gallons | 4.95 | CX50 with DHW105 Tank w/ Reverse Indirect, No Backup Element / 99 gal. Tank |
| Hitzewelle CX35DHW105NR | 80 Gallons | 3.75 | CX35 with DHW105 Tank, No Backup Element / 99 gal. Tank |
| Hitzewelle CX50DHW105NR | 93 Gallons | 3.69 | CX50 with DHW105 Tank, No Backup Element / 99 gal. Tank |
| Hitzewelle CX35DHW105RIDNR | 101 Gallons | 4.95 | CX35 with DHW105 Tank w/ Reverse Indirect, No Backup Element / 99 gal. Tank |
| Hitzewelle CX50DHW105RIDNR | 133 Gallons | 4.95 | CX50 with DHW105 Tank w/ Reverse Indirect, No Backup Element / 99 gal. Tank |
*Note: About CX65/CX75 domestic hot water packaged systems - these are so powerful that they cannot be certified as residential, or even commercial-duty residential, they are classified and certified as full commercial water heaters and therefor they don't get a UEF rating or EnergyGuide label.
What is a Reverse Indirect Tank?
In a standard indirect tank, cold water enters the tank and the heat pump heats a coil inside the tank. In a reverse indirect tank, cold water flows through the coil and the heat pump heats the tank water itself. The tank water becomes part of the closed-loop hydronic system. This design (combined with the convoluted coil) can deliver dramatically faster recovery and higher efficiency.
What is UEF?
UEF (Uniform Energy Factor) is the official U.S. Department of Energy metric used to rate residential water heater efficiency. It replaced the older EF rating in 2017 to give a more realistic “apples-to-apples” comparison under real-world conditions.


