EcoSmart ECO 36
#1 in ElectricFull review
For a large home with 300 A service that wants all electric hot water. The lifetime warranty and low price per kilowatt make it a strong value if a pro installs it.
Amazon $699$699
The EcoSmart ECO 36 rates 4.3 among electric tankless water heaters; the ThermoMate RTC68iN rates 3.4 among gas ones. The EcoSmart ECO 36 costs $400.99 less ($699 vs $1,099.99).
ThermoMate RTC68iN
#15 in GasFull review
A budget condensing heater for natural gas homes that want PVC venting and lower gas bills, if you can live with an unclear warranty.
ThermoMate $1,099.99$1,099.99
Prices were last checked October 31, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Scores side by side
These two sit in different fuel classes (electric and gas), and each is scored against the reference points for its own class, so a rating says how well each does among its own fuel peers. How we rank explains each factor.
| Factor weight | EcoSmart ECO 36 | ThermoMate RTC68iN |
|---|---|---|
| Overall rating | 4.3/5 | 3.4/5 |
| Value 35% | 64 $19.42 per kW ($699, 36 kW) | 52 $6.75 per 1,000 BTU/h ($1,099.99, 163,000 BTU/h) |
| Heating power 25% | 100 36 kW | 54 163,000 BTU/h |
| Efficiency 15% | 50 0.94 UEF | 69 0.91 UEF |
| Warranty 25% | 100 limited lifetime heat exchanger warranty | 50 heat exchanger warranty not published (neutral score used) |
Specifications
| EcoSmart ECO 36 | ThermoMate RTC68iN | |
|---|---|---|
| Heating | ||
| Fuel | Electric | Gas |
| Gas type | - | Natural gas |
| Gas input | - | 163,000 BTU/h |
| Electric power | 36 kW | - |
| Max flow | 8.8 GPM | 9.4 GPM |
| UEF | 0.94 | 0.91 |
| Condensing | - | Yes |
| Installation | ||
| Venting | - | Indoor |
| Vent type | - | PVC |
| Voltage | 240 V | - |
| Breakers | 160 A total | - |
| Weight | 18.4 lb | 50 lb |
| Features | ||
| Built-in recirculation | No | No |
| Wi-Fi | No | No |
| Heat exchanger warranty | Limited lifetime | - |