Choosing between a condensing and a non-condensing tankless water heater is a big decision for homeowners looking for efficiency, reliability, and long-term savings. Both types offer endless hot water and major space savings over old-fashioned tanks, but their technology, installation requirements, and running costs are different. This guide breaks down how each works, their real-world pros and cons, what to expect for maintenance and savings, and which model is best for your home.
Quick Picks: Best Condensing & Non-Condensing Tankless Water Heaters
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Best Condensing:
Rheem Performance Platinum 9.5 GPM Condensing Tankless Water Heater – Ultra-efficient, high capacity, ideal for families and energy-conscious homes. -
Best Non-Condensing:
Rinnai V65iN Non-Condensing Tankless Water Heater – Reliable, affordable, and easy to install almost anywhere. -
Best Premium Condensing:
Navien NPE-240A2 Premium Condensing Tankless Water Heater – Advanced controls, Wi-Fi ready, and extra-quiet operation.
How They Work: Condensing vs Non-Condensing Explained
Condensing Tankless Water Heaters
- Use a second heat exchanger to capture heat from exhaust gases, squeezing more energy out of every drop of fuel.
- Exhaust gases cool and turn into water vapor (“condensate”), which must be safely drained away.
- Operate with efficiency ratings of 90–98%, meaning more of your energy dollar goes directly to heating your water.
- Produce cooler exhaust, allowing the use of less expensive venting materials (like PVC pipe).
Non-Condensing Tankless Water Heaters
- Use a single heat exchanger; exhaust gases are much hotter and vented immediately outside.
- No condensate drain needed—simpler design and installation.
- Operate at efficiency ratings of 80–85% (still far better than most tank models).
- Require special (and pricier) metal venting due to hot exhaust.
Pros and Cons: Condensing vs Non-Condensing Tankless Heaters
| Condensing | Non-Condensing | |
|---|---|---|
| Efficiency | 90–98% (lower energy bills) | 80–85% (still efficient) |
| Exhaust Temperature | Cooler; can use PVC venting | Very hot; needs metal venting |
| Condensate Drain | Required | Not needed |
| Upfront Cost | Higher for unit; lower for venting | Lower for unit; higher for venting |
| Maintenance | Must check and clean condensate line | Fewer components, simple maintenance |
| Installation Flexibility | More options for vent location, materials | Limited to where metal venting can be routed |
| Longevity | Excellent with annual care | Also very good with basic maintenance |
| Noise Level | Generally quieter | Some models may be noisier due to exhaust |
Real-Life Costs: Installation, Operation, and Maintenance
- Condensing units have a higher initial price, but save money on venting (PVC vs metal) and ongoing energy bills due to higher efficiency.
- Non-condensing units are less expensive up front but may cost more to install due to venting and use a little more fuel each month.
- Both types should be flushed annually using a descaling kit to maintain top performance and prevent costly repairs.
- Condensate drainage must be checked and cleared at least once a year to prevent clogs and leaks.
Who Should Choose a Condensing Tankless Water Heater?
- Homeowners wanting the lowest possible energy bills (especially in areas with high fuel prices)
- Homes where PVC venting is easier to run than metal pipe (long vent runs, multiple bends, or unique locations)
- New construction or major remodels where condensate drains can be planned during plumbing work
- Families or high-demand households needing top performance, reliability, and quiet operation
Who Should Choose a Non-Condensing Tankless Water Heater?
- Smaller homes, cabins, or retrofits where a simple, proven design is ideal
- Replacement for older non-condensing units—quick swap without adding a condensate drain
- Homes where running metal vent pipe is simple and short
- Budget-focused buyers looking for an efficient, reliable upgrade over tank models
Top Reviews: Best Condensing & Non-Condensing Tankless Water Heaters
Rheem Performance Platinum 9.5 GPM Condensing Tankless Water Heater
- Super high efficiency—up to 94% UEF
- Handles 3+ showers at once
- Low NOx emissions and Wi-Fi compatible
- PVC venting for affordable, flexible installation
Final Verdict: The top choice for families or anyone wanting long-term savings and ultra-quiet operation.
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Rinnai V65iN Non-Condensing Tankless Water Heater
- Proven reliability and simple installation
- 6.5 GPM—perfect for 1–2 bath homes
- Compact, space-saving, and affordable
- Excellent warranty and easy annual maintenance
Final Verdict: The best choice for upgrades, cabins, and smaller homes.
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Navien NPE-240A2 Premium Condensing Tankless Water Heater
- Ultra-premium: advanced controls, Wi-Fi app, quiet operation
- High GPM for large homes
- Dual stainless steel heat exchangers for ultimate efficiency
- Backed by a top-tier warranty
Final Verdict: The best upgrade for demanding homeowners or luxury installs.
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Comparison Table: Condensing vs Non-Condensing Tankless Water Heaters
| Model | Type | Max GPM | Efficiency (UEF) | Venting | Home Size | Price Link |
|---|---|---|---|---|---|---|
| Rheem Perf. Platinum | Condensing | 9.5 | 0.94 | PVC | 3+ baths | View |
| Rinnai V65iN | Non-Condensing | 6.5 | 0.82 | Metal | 1–2 baths | View |
| Navien NPE-240A2 | Condensing | 11.2 | 0.97 | PVC | 4+ baths | View |
FAQ: Condensing vs Non-Condensing Tankless Water Heaters
- Are condensing tankless water heaters worth the higher price?
For many homeowners, yes—especially in high-use homes or where energy costs are high. The energy savings and cheaper venting often pay back the extra upfront cost over a few years. - Is maintenance harder on condensing units?
Only slightly—just check the condensate drain annually. Both types should be flushed every year to prevent scale. - Can I replace a non-condensing heater with a condensing model?
Yes, but you may need to add a condensate drain and switch to PVC venting. - Will a non-condensing unit still save money vs a tank?
Absolutely. Both types are much more efficient than standard tanks—non-condensing is still a big step up in comfort and savings. - Which lasts longer?
Both types are built to last 15–20 years with annual maintenance and proper water quality.
Conclusion
Whether you choose a condensing or non-condensing tankless water heater, you’ll enjoy endless hot water, extra space, and long-term savings. Condensing models shine for efficiency and flexible venting, while non-condensing models win for simple installs and proven reliability. Consider your home’s needs, installation location, and budget—then pick from the top models above for years of worry-free hot water.