This comparison is fundamentally about fuel choice, not brand choice. Rinnai is the dominant residential gas tankless brand; Stiebel is the premium electric tankless brand. They\'re not really competing for the same customer — they\'re defining the fuel decision.
The fuel decision
Choose gas (Rinnai) when
- Natural gas service available at the property
- Cold-climate winter with high simultaneous demand
- 3+ bathroom homes needing 6+ GPM consistent
- Gas is cheaper than electricity in your utility market (often the case)
- Existing gas appliances (furnace, range, dryer) — gas infrastructure already in place
- No willingness to electric-service-upgrade
Choose electric (Stiebel) when
- No gas service available; running gas line is prohibitive
- All-electric home preferred (heat pump heating, EV charging, induction range)
- Net-zero / solar-electric home where electric tankless aligns
- Smaller home with manageable peak demand (1-2 bathroom)
- Cold-climate but adequate electric service capacity
- Plan to eventually electrify everything; gas line is end-of-life
Side-by-side
| Stiebel Tempra 29 Plus | Rinnai RU199e (199K BTU) | |
|---|---|---|
| Fuel | Electric (240V, 3× 50A) | Natural gas (¾"+ line) |
| kW / BTU | 28.8 kW | 199,000 BTU = ~58 kW equivalent |
| Peak GPM at 70°F rise | 3.4 | 9.0 |
| Cold-climate performance | Good (Flow Control) | Excellent (more BTU available) |
| Annual operating cost | $400-700 (electric) | $200-450 (gas) |
| Install complexity | Major electrical service | Major gas line + venting |
| Lifespan | 15-20+ years | 15-20+ years |
| Maintenance | Inlet filter + descaling | Annual descaling + combustion analysis |
| Typical install cost | $2,000-3,500 | $3,000-5,000 (+ gas line if needed) |
The all-electric trend
Stiebel\'s position is strengthening as the electric-home trend grows. Heat pump heating, induction cooking, EV charging, and solar-electric homes all align with electric tankless. If you\'re moving toward all-electric, Tempra Plus is part of the puzzle.
For IRA tax credit eligibility, electric tankless doesn\'t qualify for Section 25C (only heat pumps do). However, the all-electric path keeps your home compatible with eventual solar-PV offset and time-of-use electric pricing.
The gas-dominant view
For now, gas operating cost is meaningfully lower than electric in most US markets. A Rinnai installed in a home with existing gas service is the practical choice for most residential applications. Stiebel becomes the answer when gas isn\'t available OR when the homeowner is intentionally electrifying.
Which to choose
- Gas service available + standard cost focus: Rinnai
- No gas service: Stiebel
- All-electric home / electrification path: Stiebel
- 3+ bathroom cold-climate high simultaneous demand: Rinnai (gas BTU capacity wins)
- Smaller home / moderate climate / electric preference: Stiebel
Bottom line
This isn\'t a brand comparison — it\'s a fuel comparison. Where gas is available and cost-effective, Rinnai is the practical answer for most residential installs. Where electric is the path (no gas, electrification, smaller home, all-electric design), Stiebel Tempra Plus is the premium electric choice.