Running out of hot water mid-shower? Traditional tank heaters waste energy heating stored water 24/7, costing families $100-200 extra annually. Enter tankless water heaters: on-demand hot water, 30-50% energy savings, and endless supply. But with models ranging from $500 to $3,000, how do you choose? This 2025 guide covers sizing for your household, real costs (gas vs electric), and installation truths—DIY or pro? We’ve analyzed top brands and real-user data to simplify your decision.
Reality check: Tankless units last 20+ years vs. 10-15 for tanks, but improper sizing leads to cold showers. Our guide ensures you get it right, potentially saving $1,000+ in energy over a decade.
Top Tankless Water Heaters for 2025
Here are some of the top tankless (on-demand) hot water heaters ranked by high efficiency (UEF / energy factor / energy‐star certification etc.), along with typical prices. Note: actual installed cost can be significantly higher (venting, gas/electric upgrades, installation labor, permits, etc.).
What to Look For in “Efficiency”
- For gas/propane units, efficiency is often expressed as Uniform Energy Factor (UEF); high‐efficiency condensing units often reach ~ 0.90+ UEF.
- Electric tankless units often have very high conversion efficiencies because almost all of the electric energy is converted to heat (minus losses, wiring etc.).
- Also consider standby losses, modulation, recirculation, etc.
- ENERGY STAR listings provide a vetted set of high‐efficiency gas tankless models. ENERGY STAR+1
Best Overall (Gas): Rinnai V53DeN Natural Gas Tankless – $600-700
- 5.3 GPM, compact, outdoor install, 10-year warranty.
Best Electric: Stiebel Eltron Tempra 36 Plus – $800-900
- 7.5 GPM, self-modulating, no venting needed.
Best Premium (Gas):Navien NPE-240A2 – $1,200-1,500
- 11.2 GPM, built-in recirculation, 0.96 UEF efficiency.
Best Value (Gas): Noritz NRC71DVNG – $1400 – 1700
- 7.1 GPM, condensing tech, ultra-low NOx.
Best for Large Homes:A.O. Smith ATI-540H-N – $1,000-1,200
- 10 GPM, commercial-grade, X3 scale prevention.
Total Savings Potential: $500-1,000/year in energy vs. old tanks.
Master Water Heater Projects: Our eBook “All About Your DIY House” (page 23) curates video tutorials on tankless installation, gas/electric models, and maintenance.Get it here.
The Psychology of Tankless Buying: Efficiency Over Impulse
Homeowners often stick with tanks due to familiarity, but tankless pays off long-term. Avoid cheap imports—opt for quality to prevent leaks or failures. Gas models excel in cold climates; electric suits smaller homes without gas lines. Factor in rebates: Up to $1,000 in 2025 for efficient units.
Gas vs Electric Tankless: Key Comparison
Pros and Cons Table
|
Feature |
Gas Tankless |
Electric Tankless |
|
Upfront Cost |
$1,000-2,800 |
$500-1,500 |
|
Operating Cost |
$220-540/year |
Higher (~$50 more/year) |
|
Efficiency (UEF) |
Up to 0.98 |
Up to 0.99 |
|
Flow Rate |
5-11+ GPM |
3-7.5 GPM |
|
Installation |
Venting required, pro recommended |
No venting, easier DIY |
|
Pros |
Lower long-term costs, handles large homes |
Cheaper install, no gas line needed |
|
Cons |
Higher initial cost, venting adds $500+ |
Limited for big households, higher energy bills |
|
Best For |
Families, cold areas |
Small homes, apartments |
2025 Insights: Gas saves ~$100/year over electric per DOE, but electric is ideal if gas isn’t available.
Sizing Your Tankless Water Heater: Household Guide
Size by GPM (gallons per minute) based on simultaneous use and groundwater temp (colder needs more power).
- 1-2 People: 5-7 GPM (e.g., 1 shower + sink)
- 3-4 People: 7-9 GPM (2 showers + appliances)
- 5+ People: 9-11+ GPM (multiple fixtures)
Calculator: Add fixture GPM (shower: 2-2.5, faucet: 1.5). For 50°F rise: Divide total GPM by efficiency factor (~0.6 for gas). Use online tools like Rheem’s for precision.
Pro Tip: Oversize 10-20% for peak demand.
The Top 8 Tankless Water Heaters (2025 Recommendations)
Gas Models (5 Picks)
1.Rinnai V53DeN Natural Gas Tankless – $600-700
Why Top Overall: 5.3 GPM for 2-3 fixtures, outdoor install saves space, WiFi-ready.
Key Features:
- 120,000 BTU
- 0.82 UEF
- 10-year heat exchanger warranty
User Feedback: “Endless hot water, cut bills by 40%.”
2.Navien NPE-240A2 Condensing Gas – $1,200-1,500
Premium Pick: 11.2 GPM, recirculation pump for instant hot water.
Pros:
- 0.96 UEF
- Built-in buffer tank
- App control
3.Noritz NRC71DVNG Condensing Gas – $800-1,000
Value Leader: 7.1 GPM, low NOx for eco-friendly.
Highlights:
- Stainless steel exchanger
- 12-year warranty
4.A.O. Smith ATI-540H-N Gas – $1,000-1,200
For Large Homes: 10 GPM, scale prevention tech.
Features: Commercial-grade, 15-year warranty.
5.Rinnai RX199iN Gas – $1,500-1,800
High-Capacity: 11 GPM, smart sense tech.
Electric Models (3 Picks)
6.Stiebel Eltron Tempra 36 Plus – $800-900
Best Electric: 7.5 GPM, advanced flow control.
Why Specific: No cold surprises, 99% efficient.
7.Rheem RTEX-36 Electric – $600-700
Budget Electric: 7.03 GPM, adjustable temp.
Tested: Reliable for 2-3 baths.
8.EcoSmart ECO 27 Electric – $400-500
Entry-Level: 6 GPM, self-modulating.
Step-by-Step Installation Guide
- Prep: Shut off water/gas/electric. Tools:Pipe wrench,pliers.
- Mount Unit: Wall-mount, ensure venting (gas) or wiring (electric).
- Connect Lines: Water in/out, gas/electric supply.
- Test: Flush system, check leaks, adjust temp.
DIY vs Pro: DIY possible for electric ($0 labor), but gas requires pro ($800-3,000). Total install: $1,200-3,500.
Safety: Permits needed; improper venting risks CO poisoning.
Essential Tools for Installation
From ourFirst-Time Homeowner Tool Kit:
- Pipe Wrench – $20-30
- Adjustable Wrench Set – $25-35
- Non-Contact Voltage Tester – $15-25
- Flashlight – $20-30
- Safety Gear – $50-75
Total Tool Cost: $150-250.
Smart Shopping Strategy
Phase 1: Assess Needs ($0)
Calculate GPM, check gas/electric availability.
Phase 2: Core Purchase ($500-1,500)
Buy unit; add venting ($200-500 for gas).
Phase 3: Install & Maintain ($800-3,000)
Pro install; annual descaling ($100).
Money-Saving Tips
- Rebates: $300-1,000 for efficient models.
- Energy Star Rebates: 30% up to $600.
- Sales: Black Friday 20-40% off.
- Compare: Gas for savings, electric for simplicity.
- Reviews: 4+ stars, 1,000+ ratings.
Final Thoughts
Tankless water heaters transform home efficiency—endless hot water, lower bills, longer life. Size right (7-10 GPM for most families), budget $1,500-4,000 total, and consider gas for max savings. Reference our book “All About Your DIY House” (water heaters section, page 23) for video guides on tankless vs. tank, gas/electric, and parts. VisitAll About Your DIY House for more—upgrade today and never run cold again!