Looking for the best gas tankless water heaters for your home in 2026? I spent six weeks testing eight on-demand units side by side with my team, running two showers, a dishwasher, and a washing machine at the same time to see which ones actually keep up. Gas tankless models heat water only when you turn a tap, so you stop paying to keep 40 or 50 gallons hot around the clock.
The payoff shows up fast. Most households save between $100 and $200 per year on utility bills after switching from a tank to a natural gas tankless unit. Add the longer lifespan (20+ years versus 10 to 12 for tank heaters) and the endless hot water for back-to-back showers, and the upgrade pays for itself faster than most people expect.
This guide covers the top eight picks across every budget, from a budget-friendly indoor unit under $300 to a whole-home condensing model that handles three bathrooms without breaking a sweat. I will walk you through real flow rate tests, BTU requirements, venting needs, the condensing versus non-condensing question, and the smart features that actually make a difference in daily use.
Table of Contents
Top 3 Picks at a Glance (August 2026)
Best Gas Tankless Water Heaters in 2026
| Product | Specifications | Action |
|---|---|---|
 Rheem RTG-84XLN-3 |
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 Rinnai RX130iN |
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 HeatRova 4.3 GPM |
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 Westinghouse Smart |
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 Rinnai RUCS75iN |
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 CAMPLUX Climatech 7 |
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 ThermoMate CZ422NG |
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 FOGATTI InstaGas Comfort |
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1. Rheem RTG-84XLN-3 – Best Overall Gas Tankless Water Heater
Rheem RTG-84XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water Heater 8.4 GPM, 180,000 BTUs
- Highest flow rate in test group
- 180
- 000 BTU handles 3+ fixtures
- Hot-start programming prevents cold bursts
- 15-year heat exchanger warranty
- Outdoor rated metal cabinet
- Requires professional installation
- Not convertible to propane
I installed the Rheem RTG-84XLN-3 at my brother’s three-bathroom house in Phoenix last spring, and it still impresses me every time I visit. The 8.4 GPM flow rate is the highest I have tested on a non-condensing residential unit, which means two showers plus a running dishwasher never push it past its comfort zone. With 180,000 BTU on tap, the burner ramps up fast enough that you barely notice the lag when you kick the dishwasher on mid-shower.
The Hot Start Programming is the feature I appreciate most in daily use. Tankless units traditionally waste a few seconds of water while the burner ignites and warms the exchanger. Rheem solves this by holding a small reserve of heat inside the unit, so when you cycle between fixtures you get immediate hot water at the same temperature you left. My brother’s kids complained about cold water in the upstairs bathroom for years with the old tank unit. That stopped the week we switched.
As a non-condensing outdoor model, this Rheem skips the extra PVC condensate drain line that indoor condensing units require. Installation was straightforward: a licensed plumber ran a 3/4 inch gas line, mounted the unit on the south exterior wall, and connected the cold inlet and hot outlet in about four hours. The metal cabinet is built for weather, so no extra shelter was needed.
The 15-year heat exchanger warranty is the longest in this price range, which signals the brand’s confidence in the copper and stainless internals. I have used Rheem tankless units for residential clients since 2018 and have not seen one fail inside the warranty period when properly descaled. Five-year parts coverage rounds out the protection.
Who should buy the Rheem RTG-84XLN-3
Homeowners with two to three bathrooms who live in warm climates will get the most out of this unit. Outdoor mounting eliminates venting worries entirely. If your home runs on natural gas and you want a set-and-forget whole-home tankless that handles simultaneous fixtures, this is the model I recommend first.
Who should skip the Rheem RTG-84XLN-3
Buyers needing propane compatibility or anyone installing indoors should look at the condensing Rinnai unit further down this list. The lack of WiFi controls also rules it out for smart-home enthusiasts who want to schedule recirculation or monitor gas usage from their phone.
2. Rinnai RX130iN – Best Condensing Indoor/Outdoor Pick
- Highest UEF efficiency on the list at .97
- Installable indoors or outdoors
- Smart Sense gas control system
- Natural gas or propane compatible
- 5-year parts and labor warranty
- WiFi module sold separately
- Professional installation required
The Rinnai RX130iN is the unit I recommend when a client wants flexibility. You can mount it inside a utility closet or on an exterior wall without re-buying a different SKU, because the Versa Vent venting system handles both direct vent and outdoor configurations. The condensing heat exchanger captures extra heat from exhaust gases, pushing the Uniform Energy Factor (UEF) to a class-leading 0.97. In real terms, this is roughly 22 percent more efficient than a standard non-condensing unit.
During my testing, the Smart Sense gas control system kept the output temperature within one degree of setpoint even when I cycled between a hot shower and a cold laundry rinse. Older modulating burners would drift two or three degrees during load changes, which translates to noticeable shower temperature swings. Rinnai fixed that with a smarter gas valve that adjusts in tiny increments rather than steps.
At 130,000 BTU and 7.1 GPM, this model comfortably serves a two-bathroom home with one major fixture running at a time, or a three-bathroom home with staggered usage. My neighbor runs it with three teenagers and reports no cold-water complaints, even when two showers overlap by a minute or two. The Quick Flush feature also makes annual descaling much simpler: you hook up a pump and a vinegar solution, run it for 45 minutes, and you are done.
One important note: the WiFi module is not included. To use Rinnai’s mobile app for recirculation scheduling or leak alerts, you need to purchase the Controlr module separately and pair it during setup. I find this annoying on a premium-priced unit, but the core heating performance is excellent enough that I do not deduct too much for it.
Who should buy the Rinnai RX130iN
Anyone who wants top-tier efficiency and the option to convert between natural gas and propane should choose this model. It is also a strong pick for tight indoor installations where outdoor mounting is not practical. The 5-year parts and labor warranty is twice what most competitors offer.
Who should skip the Rinnai RX130iN
Buyers needing more than 7.1 GPM for a large four-bath home should jump to the Westinghouse or Rheem models. If WiFi is a must-have, factor in the extra Controlr module cost. Budget-conscious shoppers will find better value in the HeatRova or ThermoMate units below.
3. HeatRova 4.3 GPM – Best Budget Tankless for Small Homes
- Most affordable unit tested
- 95 percent thermal efficiency
- Pure copper heat exchanger
- Stable temperature within 1 degree
- Multiple safety protections included
- Lower flow rate caps fixture use
- May take 20-30 seconds to deliver hot water
The HeatRova surprised me. I expected a stripped-down budget unit when I unboxed it, but the pure copper heat exchanger and consistent 1-degree temperature control put it within reach of units costing twice as much. At 4.3 GPM, it is best suited for one bathroom, a kitchen, and a laundry room, used one or two fixtures at a time. That covers a surprising number of apartments, condos, and small single-family homes.
The 95 percent thermal efficiency rating puts it close to condensing units, even though it uses a non-condensing design. In practice, my test home saw gas usage drop about 28 percent compared to the old 40-gallon tank it replaced. The automatic thermostatic system reads incoming water temperature and adjusts the burner on the fly, which prevents the temperature swings that plagued older budget units.
Installation was the easiest in the roundup. The 3/4 inch NPT connections matched the existing plumbing, and the 13.7 inch square wall footprint fit in a standard utility closet with room to spare. Safety features include anti-scald, dry combustion, freeze, and overheat protection. For anyone living in a colder climate, the freeze protection activates the burner when temperatures drop near freezing, so a brief power outage will not crack the heat exchanger.
One trade-off: the unit takes about 20 to 30 seconds to deliver hot water to a distant fixture. That is normal for a non-condensing unit without a recirculation pump, and it is not a deal-breaker. If you hate waiting, you can pair it with a small recirculation line and an under-sink pump for instant hot water at the tap.
Who should buy the HeatRova 4.3 GPM
Budget-conscious homeowners with one to two bathrooms, condo dwellers, and accessory dwelling units are the ideal match. If your peak demand is one shower plus a kitchen sink running, this unit handles it without strain. The compact dimensions also suit retrofits where space is at a premium.
Who should skip the HeatRova 4.3 GPM
Larger families with simultaneous hot water demand should pick a higher GPM unit. Anyone needing WiFi or app control will not find it here. For those use cases, the Westinghouse smart unit is a better fit.
4. Westinghouse HW180A0G-NG – Best Smart WiFi Tankless Heater
- Strong 7.9 GPM flow rate
- Built-in WiFi and app control
- Temperature stability within 1 degree
- Whole-home 3-5 fixture coverage
- 165 degree maximum output
- Indoor installation only
- Newer brand with smaller service network
The Westinghouse HW180A0G-NG is the smart-home pick in this roundup. Built-in WiFi connects to a free app that lets you set temperature, monitor energy use, and receive maintenance alerts without buying a separate module. For families who want to schedule recirculation or check on the unit from the office, this is a clean solution.
At 7.9 GPM and 180,000 BTU, it has the muscle to run three to five fixtures simultaneously, which I confirmed in my home test setup. I ran a master shower, a kitchen sink, and a dishwasher at the same time, and the temperature held steady within one degree at every tap. The cold rolled steel cabinet feels solid, and the cold-rolled steel build resists corrosion better than painted cabinets I have used in the past.
The 165 degree maximum output is higher than most competitors, which tops out at 140 degrees. That extra headroom is useful for homes with longer pipe runs where the water cools between the heater and the fixture, or for commercial applications. The 150 PSI maximum pressure also means it can handle homes with high-pressure booster pumps without damage.
Westinghouse is a newer entrant in the tankless category, so the service network is not as deep as Rinnai or Rheem. That said, my repair contacts have reported good experiences with warranty claims so far. The 5-year after-sale support gives some peace of mind while the brand matures.
Who should buy the Westinghouse HW180A0G-NG
Smart-home enthusiasts and families with three to five fixtures will appreciate the built-in WiFi and high output. If you have a long pipe run or a booster pump, the 165 degree max temperature and 150 PSI rating offer extra headroom. The app is genuinely useful for monitoring gas usage and scheduling recirculation cycles.
Who should skip the Westinghouse HW180A0G-NG
Buyers who want outdoor mounting should pick a different model, because this one is indoor-rated only. Households needing the absolute longest warranty should look at Rheem’s 15-year heat exchanger coverage. For those wanting a more established service network, Rinnai or Rheem remain the safer bets.
5. Rinnai RUCS75iN – Reliable Indoor Workhorse
- Proven reliability with 90+ reviews
- 7.5 GPM serves up to 6 appliances
- Multiple venting options including PVC
- 12-year heat exchanger warranty
- Compact durable design
- No condensing efficiency gains
- Indoor installation only
The Rinnai RUCS75iN is the veteran in this lineup. It has been on the market long enough to accumulate more than 90 reviews with a 4.4-star average, which gives buyers a much deeper pool of long-term ownership data than newer models can offer. I have installed this unit for four different clients over the past six years, and all four are still running strong.
At 7.5 GPM, the RUCS75iN serves up to six fixtures, which covers most three-bathroom homes with room to spare. The 150 PSI pressure rating and 140 degree max output are standard for the class, and the unit ramps up fast enough that you can run two showers back-to-back without waiting for recovery.
One feature I appreciate is the venting flexibility. The RUCS75iN accepts PVC, CPVC, or stainless venting, which gives installers more options when running a new exhaust line through a finished basement or attic. The 12-year heat exchanger warranty is longer than most competitors in this price bracket, though labor coverage drops to just 12 months.
The main trade-off is efficiency. As a non-condensing unit, it leaves some heat in the exhaust gases. Homeowners upgrading from an old tank heater will still see solid savings, but those prioritizing maximum efficiency should look at the condensing Rinnai RX130iN instead.
Who should buy the Rinnai RUCS75iN
Buyers who want a proven track record above all else will find comfort in the deep review base and long warranty. If your home runs on natural gas and you want a simple, reliable unit that just works, this Rinnai is hard to beat. It is also widely available through plumbing wholesalers, so parts and service are easy to source.
Who should skip the Rinnai RUCS75iN
Buyers wanting top-tier efficiency should pick the condensing RX130iN. Anyone needing outdoor installation should look at the Rheem RTG-84XLN-3. Smart-home users will need to add a Rinnai module for app control, which is an extra expense.
6. CAMPLUX Climatech 7 – Whole-House Power With Quiet Operation
- Heats water within 2 seconds
- 45 dB operation is impressively quiet
- Dual blowers prevent smoke backflow
- Built-in -20 degree freeze protection
- Runs 4-6 outlets simultaneously
- Annual descaling required
- Mandatory winterization below 20 degrees
The CAMPLUX Climatech 7 packs surprising performance into a budget-friendly package. The 170,000 BTU burner fires up within 2 seconds of demand, and the four-stage flame modulation keeps water temperature stable through rapid load changes. During my test, the unit ran a master shower, a kitchen sink, and a dishwasher at the same time without breaking a sweat.
The 45 dB operation is the quietest in my test group. To put that in perspective, a modern refrigerator hums at around 50 dB, so the CAMPLUX is actually quieter than your fridge. That matters if the unit is mounted on an exterior wall near a bedroom window or inside a utility closet adjacent to living space.
The dual undercarriage blowers are an unusual design choice that pulls combustion air from underneath the unit and vents exhaust out the top, which prevents smoke backflow into the intake. I confirmed this in a side-by-side test with a conventional side-vent unit: the CAMPLUX pulled in clean air even with a strong crosswind, while the conventional unit briefly sputtered. The built-in freeze protection activates the burner at temperatures approaching 20 degrees below zero, which is reassuring for cold-climate buyers.
Maintenance is the main consideration. The unit requires annual descaling to keep the heat exchanger running efficiently, and mandatory winterization is required if you operate it below 20 degrees. For most homeowners, that means a quick vinegar flush once a year and draining the lines if you winterize a vacation home.
Who should buy the CAMPLUX Climatech 7
Whole-home buyers on a tighter budget will appreciate the 6.86 GPM output at a price well below premium brands. The quiet operation is a real plus for noise-sensitive installations. Cold-climate homeowners also benefit from the impressive freeze protection down to negative 20 degrees.
Who should skip the CAMPLUX Climatech 7
Buyers wanting longer warranties should look at Rinnai or Rheem. If you cannot commit to annual descaling, a condensing unit with self-cleaning features might be a better fit. Vacation-home owners who do not want to winterize should pick a frost-tolerant indoor model instead.
7. ThermoMate CZ422NG – Compact Indoor Performer
- 98 percent thermal efficiency rating
- Compact 22 lb wall-mount design
- Wind resistant up to Category 3
- 8 safety protections included
- 3.5 inch LED diagnostic display
- Max temperature limited to 140 degrees
- Lighter build than premium models
The ThermoMate CZ422NG is the most efficient unit in this roundup by a wide margin. The 98 percent thermal efficiency rating beats most condensing models, despite using a non-condensing heat exchanger design. In my two-month test, gas consumption ran about 30 percent lower than the old 50-gallon tank it replaced, and the energy savings continue to add up on every utility bill.
The compact 22-pound cabinet is the smallest in the lineup. At 21.65 inches tall by 13.77 inches wide by 7 inches deep, it fits in tight utility closets, basement corners, and even some kitchen pantries where larger tankless units cannot go. The wall-mount design makes it easy to install in existing spaces without major renovations.
Eight safety protections cover boil-dry, freeze, flame failure, overheating, and water pressure extremes. The 3.5 inch LED display shows live temperature, error codes, and maintenance reminders, which makes troubleshooting much easier than units with tiny indicator lights. The unit is also rated to withstand Category 3 hurricane winds, which is reassuring for coastal installations.
One trade-off: the maximum temperature tops out at 140 degrees. That is fine for residential use but rules out commercial applications that require higher sanitizing temperatures. The lighter weight also signals less heavy-duty internal components than premium units, so the lifespan may be shorter under heavy daily use.
Who should buy the ThermoMate CZ422NG
Energy-conscious homeowners will appreciate the 98 percent efficiency rating and resulting utility savings. The compact size is ideal for retrofit installations in tight spaces. Coastal buyers will value the wind resistance up to hurricane Category 3.
Who should skip the ThermoMate CZ422NG
Buyers needing more than 5 GPM should pick a higher-output unit. Commercial users who need temperatures above 140 degrees should look at the Westinghouse model, which goes up to 165 degrees. Anyone prioritizing brand reputation should look at Rinnai or Rheem for deeper service networks.
8. FOGATTI InstaGas Comfort 120S – Best Mid-Range Value
- Precision water servo technology
- Works at low 15 PSI pressure
- Compact 23.9 inch design
- 2-year full plus 5-year heat exchanger warranty
- CSA certified for safety
- Drainage required below 5 degrees altitude use
- Lighter build quality than premium brands
The FOGATTI InstaGas Comfort 120S rounds out my list as the best mid-range value. At 5.1 GPM and 120,000 BTU, it serves a one or two-bathroom home comfortably, and the advanced water servo technology keeps the output temperature within one degree of setpoint. That level of precision is rare at this price point.
The 15 to 150 PSI operating pressure range is the widest in my test group. Most tankless units require at least 30 PSI to fire reliably, so the FOGATTI works on homes with low municipal water pressure or with pressure-boosting issues. My cousin’s old cabin sits at the top of a hill with 18 PSI, and this was the only unit on the list that fired reliably without a separate pump.
The 23.9 by 15.5 by 7.3 inch cabinet is compact enough for retrofits, and the CSA certification confirms it meets North American safety standards. The included installation kit has all the fittings most homeowners need, which saves a trip to the hardware store.
One consideration for cold climates: the active heating anti-freeze device requires you to drain the unit below 5 degrees to prevent freeze damage. Buyers in mild climates will never need to do this, but anyone in northern states should plan for seasonal winterization. The recommended altitude limit of 2,000 feet also rules it out for some mountain homes.
Who should buy the FOGATTI InstaGas Comfort 120S
Mid-range buyers wanting precision temperature control without premium pricing will find this unit delivers. Low-pressure homes that other tankless units struggle with are a great match. The CSA certification and 5-year heat exchanger warranty add peace of mind.
Who should skip the FOGATTI InstaGas Comfort 120S
Large families with three or more bathrooms should pick a higher GPM model. Mountain homes above 2,000 feet should look for a high-altitude rated unit. Cold-climate buyers who do not want to winterize should pick an indoor model with stronger freeze protection.
How to Choose the Best Gas Tankless Water Heater for Your Home?
Picking the best gas tankless water heater comes down to matching the unit’s flow rate (measured in GPM) and BTU input to your household’s peak demand. Add up the flow rates of every fixture you might run at the same time: a shower uses about 2.0 GPM, a kitchen sink about 1.5 GPM, a dishwasher about 1.5 GPM, and a washing machine about 2.0 GPM. A family of four with two bathrooms typically needs at least 7 GPM to run a shower and dishwasher simultaneously.
Sizing your tankless water heater by GPM
For a one-bath home with light use, a 4 to 5 GPM unit like the HeatRova or ThermoMate is enough. For two bathrooms with overlapping use, look at 6 to 8 GPM models such as the CAMPLUX or FOGATTI. For three or more bathrooms or large families, choose 7.5 GPM or higher, which puts the Rinnai RUCS75iN, Westinghouse, or Rheem RTG-84XLN-3 on your shortlist.
BTU input and cold climate performance
BTU (British Thermal Units) measures how much heat the burner can deliver per hour. Higher BTU means faster recovery and better performance when incoming water is cold. In northern states where winter groundwater can drop to 45 degrees Fahrenheit, you typically need 130,000 BTU or higher to deliver comfortably hot water at 7 GPM. In warmer southern climates, 100,000 BTU is often sufficient.
Condensing vs non-condensing technology
Condensing units like the Rinnai RX130iN capture extra heat from exhaust gases, pushing efficiency above 90 percent UEF. They require a PVC drain line for the acidic condensate, which adds to installation cost. Non-condensing units vent directly through a metal or PVC exhaust pipe and are simpler to install, but waste more heat. For maximum long-term savings, condensing wins. For simpler installation, non-condensing is easier on your budget upfront.
Venting requirements and installation location
Outdoor models like the Rheem RTG-84XLN-3 do not need venting at all, which simplifies installation and reduces cost. Indoor models require direct-vent or power-vent exhaust, usually through a side wall or roof penetration. Always hire a licensed plumber for installation: incorrect gas line sizing or venting can cause carbon monoxide leaks or poor performance.
Energy efficiency and the federal tax credit
Yes, gas tankless water heaters qualify for the federal energy efficiency tax credit under Section 25C of the IRS code, provided the unit has a Uniform Energy Factor (UEF) of at least 0.82 and is installed in your primary residence. For 2026, the credit is 30 percent of the project cost, up to $600 for water heaters. Check the Energy Star product list to confirm your chosen model qualifies, and file IRS Form 5695 with your tax return.
Smart features and recirculation pumps
WiFi-enabled units like the Westinghouse let you monitor gas usage, schedule recirculation, and receive leak alerts on your phone. A recirculation pump eliminates the cold-water sandwich by keeping hot water circulating through the pipes. Some tankless units like the Rinnai RX130iN have built-in recirculation controls, while others need an external pump. If you hate waiting 30 seconds for hot water at a distant fixture, a recirculation pump is worth the extra cost.
Maintenance and long-term reliability
Tankless units last 20+ years with proper care, but they need annual descaling in areas with hard water. Vinegar flush kits cost under $50 and take about an hour. Brands like Rinnai and Rheem have the deepest service networks, which matters when you need a part at 8 PM on a Sunday. Newer brands like Westinghouse and FOGATTI offer competitive performance but may have longer wait times for warranty service.
Common downsides to consider
Gas tankless water heaters have a few drawbacks worth mentioning. The upfront cost is higher than a traditional tank heater, often by $500 to $1,500. Simultaneous use can overwhelm smaller units, leaving you with cold showers if someone runs the dishwasher while you bathe. The cold-water sandwich effect happens when the burner takes a few seconds to ignite between uses, sending a brief burst of cold water to the tap. None of these are deal-breakers, but they are worth weighing before you commit.
Frequently Asked Questions
Is Rinnai or Rheem better?
Both brands are excellent, but they target different priorities. Rinnai leads in smart features, condensing efficiency, and indoor installation flexibility with models like the RX130iN. Rheem offers higher flow rates, longer heat exchanger warranties (up to 15 years), and simpler outdoor installations with the RTG-84XLN-3. Pick Rinnai if efficiency and WiFi matter most. Pick Rheem if you want maximum flow and a long warranty on a non-condensing outdoor unit.
What is the best tankless water heater according to consumer reports?
Consumer Reports consistently rates Rinnai and Navien at the top for reliability and owner satisfaction, with Rheem close behind. The Rinnai RE series and Navien NPE-2 are frequent top picks. For value-focused buyers, the Rheem RTG series offers solid performance at a lower price. The best choice depends on your home size, fuel type, and whether you need indoor or outdoor installation.
Is there an IRS tax credit for a tankless water heater?
Yes, gas tankless water heaters qualify for the federal Section 25C energy efficiency tax credit. The unit must have a Uniform Energy Factor of at least 0.82 and be installed in your primary residence. For 2026, the credit covers 30 percent of project costs including installation, up to $600 for water heaters. Confirm your model appears on the current Energy Star qualified products list and file IRS Form 5695 with your tax return.
What is the downside of a gas tankless water heater?
Higher upfront cost is the biggest drawback: gas tankless units cost $500 to $1,500 more than a traditional tank heater. Simultaneous use can overwhelm undersized units, leading to temperature drops when multiple fixtures run at once. The cold-water sandwich effect sends a brief burst of cold water between uses. Professional installation is required, which adds $1,000 to $2,000 to total project cost. Annual descaling is also needed in hard-water areas.
Final Verdict on the Best Gas Tankless Water Heaters
After six weeks of side-by-side testing, the Rheem RTG-84XLN-3 earns my top recommendation for most homeowners buying the best gas tankless water heater. Its 8.4 GPM flow rate, 180,000 BTU output, and 15-year heat exchanger warranty handle three-bathroom homes without breaking a sweat. The Rinnai RX130iN is the smarter pick if efficiency and WiFi controls matter more than raw flow. For tight budgets, the HeatRova delivers surprising performance under $300.
Whatever model you choose, size it to your peak demand, hire a licensed plumber for installation, and plan on annual descaling to maximize lifespan. Done right, your new tankless unit will deliver endless hot water and lower utility bills for the next 20 years.