Friedrich FDTGH-S10I vs Rinnai RX180I REU-NB2934FF-US
The Rinnai RX180I REU-NB2934FF-US is the more efficient unit: UEF 0.98 versus 0.96 — about 2% less energy for the same hot water. At national average rates that works out to about $251/year for the Rinnai RX180I REU-NB2934FF-US against $255/year for the Friedrich FDTGH-S10I — a $4 annual difference. The Rinnai RX180I REU-NB2934FF-US sustains the higher flow (5.3 GPM vs 5.2 GPM under the DOE test).
| Friedrich FDTGH-S10I | Rinnai RX180I REU-NB2934FF-US | |
|---|---|---|
| Uniform Energy Factor (UEF) | 0.96 | 0.98 |
| Fuel | Natural Gas, Propane | Natural Gas, Propane |
| Max flow rate | 5.2 GPM | 5.3 GPM |
| Draw pattern | High | High |
| Annual gas use (natural gas) | 176 therms/yr | 173 therms/yr |
| Gas input rate | 180 kBTU/h | 180 kBTU/h |
| Max current draw | 2 A | 4 A |
| Vent type | Direct Vent | Power Direct Vent |
| Recovery efficiency | 98 % | 98 % |
| Smart / connected capable | No | No |
| Minimum activation flow | 0.4 GPM | 0.1 GPM |
| Annual propane use | 192.35 gal/yr | 189.07 gal/yr |
| Vent size | 2 | 2 |
| Height | — | 25.8 in |
| Diameter | — | 11.4 in |
| Width | 18.1 in | 18.5 in |
| Depth | 13.6 in | 11.4 in |
| ENERGY STAR certified | Yes | Yes |
Frequently asked questions
Which costs less to run, the Friedrich FDTGH-S10I or the Rinnai RX180I REU-NB2934FF-US?
The Rinnai RX180I REU-NB2934FF-US: about $251/year versus $255/year for the Friedrich FDTGH-S10I at national average rates — a $4 annual difference.
Are the Friedrich FDTGH-S10I and Rinnai RX180I REU-NB2934FF-US both ENERGY STAR certified?
Yes — every water heater in this database is drawn from the U.S. EPA ENERGY STAR certified water heater datasets.