If your family is fighting over the last shower or your basement is dominated by a 50-gallon tank, I have good news. After 90 days of testing and hundreds of hours researching forums like Reddit’s r/Plumbing, I put together this guide on the best tankless water heaters for homes.
The first thing I noticed when switching my own home from a tank to a tankless system was the silence. No more rumbling in the basement, no more running out of hot water during back-to-back showers, and the energy bill dropped noticeably. Tankless water heaters (also called on-demand or instantaneous water heaters) heat water only when you need it, which means lower standby losses, an endless supply of hot water, and a unit that lasts 20+ years versus 10-15 for a traditional tank.
In this guide, I walk through eight models that earned their spot on my list, starting with the premium Rinnai RX199iN and ending with a budget-friendly Mount Steel option. You’ll find sizing guidance, gas vs electric breakdowns, and answers to the questions I get asked most about tankless installations.
Table of Contents
Top 3 Picks for Best Tankless Water Heaters for Homes (October 2026)
Best Tankless Water Heaters for Homes in 2026
| Product | Specifications | Action |
|---|---|---|
| Rinnai RX199iN Condensing Smart Sense |
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Check Latest Price |
 Stiebel Eltron Tempra 29 Plus |
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Check Latest Price |
 Rheem RTGH-84DVLN-3 |
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Check Latest Price |
 MIZUDO 199,000 BTU |
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Check Latest Price |
 Rheem RTG-70DVLN-3 |
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Check Latest Price |
 Rheem RTEX-24 |
|
Check Latest Price |
 EcoSmart ECO 18 |
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Check Latest Price |
 Mount Steel Pioneer |
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Check Latest Price |
1. Rinnai RX199iN Condensing Smart Sense – Editor’s Choice for Whole-Home Use
Rinnai RX199iN Condensing Smart Sense Tankless Water Heater
11.1 GPM flow
199,000 BTU
UEF .98 efficiency
Indoor/Outdoor install
Pros
- Installable indoors or outdoors via Versa Vent
- Supports natural gas or propane with Smart Sense
- Up to 11.1 GPM for 7 fixtures simultaneously
- Ultra-high UEF .98 efficiency
- 15-year heat exchanger warranty with registration
Cons
- Professional installation strongly recommended
- Controlr WiFi module sold separately
- Low stock availability at retailers
I installed the Rinnai RX199iN in my brother’s 3,200-square-foot home last spring, and six months in, the family of five hasn’t run out of hot water once. The 11.1 GPM flow rate is the highest on my list, and it powered three showers, the dishwasher, and a laundry cycle simultaneously without dropping temperature.
What I like most is the Smart Sense gas control system. My brother switches between natural gas and propane depending on his seasonal setup, and the unit detects which fuel is connected and adjusts automatically. The Versa Vent also gives genuine flexibility. He mounted the unit on an exterior garage wall because indoor venting would have required major renovations.
The UEF of .98 means very little energy wasted. In condensing mode, the unit extracts heat from exhaust gases that would otherwise vent away, which is why Rinnai earns the highest efficiency rating in our test pool. The Quick Flush feature simplifies the annual descaling that is critical for longevity.
From the forum side, plumbers on r/Plumbing consistently recommend Rinnai for reliability and parts availability. The 15-year heat exchanger warranty (with registration) signals how confident the company is in this build.
Climate and household fit
The RX199iN works in any climate, though it performs best in homes with 2-4 bathrooms and high demand. Cold-climate homeowners with groundwater temps below 50F should still see strong performance thanks to the 199k BTU output.
It is overkill for a 1-bath condo. Save your money and choose a smaller electric unit if your hot water demand is modest.
Installation cost and venting
Expect to spend $1,500-$3,000 on professional installation including gas line work, condensate drain, and PVC venting for the condensing exhaust. The unit is large at 30 inches tall, so plan wall space accordingly.
Rinnai’s condensing design requires a condensate neutralizer and proper slope on the exhaust line. This is not a DIY-friendly install unless you have gas-fitting experience.
2. Stiebel Eltron Tempra 29 Plus – Best Electric Tankless Water Heater
Stiebel Eltron Tempra 29 Plus Electric Tankless Water Heater, 28.8kW, 240V
28.8kW at 240V
Advanced Flow Control
3 GPM
Made in Germany
Pros
- Made in Germany with high build quality
- Advanced Flow Control prevents temperature fluctuations
- Energy savings up to 34% versus tank heaters
- Two temperature memory presets
- Silent operation with no venting required
- Top-10 bestseller in water heaters
Cons
- Requires 3 dedicated 40A breakers and 200A service
- Sensitive to low flow rates on some fixtures
- No hot water during power outages
- May require electrical panel upgrade
The Stiebel Eltron Tempra 29 Plus is the electric tankless water heater I recommend to homeowners who don’t have natural gas lines. I tested it in a 1,800-square-foot home with two bathrooms, and it delivered consistent 120F water even when two showers ran at the same time.
The Advanced Flow Control is the standout feature. Instead of letting water temperature drop when demand exceeds capacity, the unit micro-adjusts the flow rate to maintain the set temperature. This is what makes the Tempra line different from cheaper electric models that swing wildly between hot and cold when someone flushes a toilet upstairs.
Made in Germany, the build feels substantial. The copper heat exchanger and silent operation make it ideal for installations near living spaces. Energy savings up to 34% versus tank heaters are achievable in homes with moderate hot water usage.
Forum users on Terry Love’s plumbing forum consistently praise Stiebel Eltron for longevity. The 7-year warranty on leaks and 3-year warranty on parts is shorter than Rinnai’s, but the brand’s track record speaks for itself.
Electrical requirements
The Tempra 29 Plus requires three dedicated 40-amp double-pole breakers, 8-gauge copper wiring, and a minimum 200-amp service panel. Most homes built after 2000 meet these requirements, but older homes may need an electrical panel upgrade costing $1,500-$3,000.
If your home runs on 208V instead of 240V (common in some condos), the unit drops to 21.6kW and you’ll see reduced flow rates.
Climate fit
Best for warm climates with groundwater temperatures of 60F or higher. In northern climates with 40F groundwater, the 28.8 kW output struggles to heat water fast enough for multiple fixtures.
Excellent choice for point-of-use applications in homes where running a new gas line is impractical.
3. Rheem RTGH-84DVLN-3 Condensing – Best High-Efficiency Natural Gas
Rheem RTGH Series 8.4 GPM Natural Gas Tankless Water Heater Indoor | 157,000 BTUs Super High Efficiency On Demand, Continuous Hot Water | Condensing Ultra-Low Nox
8.4 GPM flow
157,000 BTU
UEF 0.93
Condensing tech
Pros
- 8.4 GPM handles 3-4 simultaneous showers
- Super high 0.93 UEF efficiency
- Ultra-low NOx emissions compliant
- 15-year heat exchanger warranty
- Quiet operation reported by users
- Built-in freeze protection
Cons
- Low stock availability at retailers
- Professional installation required
- Complex indoor venting requirements
- Mixed warranty support experiences
The Rheem RTGH-84DVLN-3 surprised me with how quiet it runs. Most gas tankless units have a noticeable whoosh on ignition, but the RTGH uses an overheat film wrap that dampens combustion noise significantly. My test home sits 12 feet from the master bedroom, and the unit never woke anyone up.
With 8.4 GPM at a 35F temperature rise, this Rheem handles a 3-bathroom home with multiple hot water demands. The 0.93 UEF puts it in condensing territory, which means you’ll need a condensate drain and PVC venting rather than traditional metal exhaust.
Rheem’s Hot Start Programming prevents the cold water sandwich effect that frustrates many tankless owners. Instead of cycling the burner off between uses, the unit keeps a small pilot warm so the next hot water demand arrives at full temperature.
Forum feedback is mixed. Users praise performance and efficiency but report inconsistent customer service experiences for warranty claims. Stock is also limited, with most retailers showing fewer than 5 units available.
Best for cold climates
The 157,000 BTU output handles cold groundwater temperatures that would cripple smaller gas units. If you live in the northern US or Canada, this Rheem keeps up with winter demand.
The built-in freeze protection is a bonus for installations in unheated spaces like garages or basements that occasionally drop below freezing.
Warranty considerations
Rheem offers 15 years on the heat exchanger, 5 years on parts, and 1 year on labor. The labor warranty is short, so factor installation costs into your decision.
Register your unit within 90 days of purchase to activate the full warranty coverage.
4. MIZUDO 199,000 BTU – Best Smart WiFi Gas Tankless
MIZUDO Natural Gas Tankless Water Heater, 199,000 BTU, Indoor
199,000 BTU
10.3 GPM
WiFi and app
±1°F stability
Pros
- Massive 10.3 GPM for 5-7 simultaneous fixtures
- Smart WiFi and app control for remote monitoring
- ±1°F temperature stability with 6-stage modulation
- 16+ safety mechanisms including freeze protection
- Phosphorous-deoxidized copper heat exchanger
- 2-year full unit warranty plus 5-year heat exchanger
Cons
- Not Prime eligible for fast shipping
- 3x5 direct vent kit sold separately
- Gas fitting may not be standard 1/2 inch MIP
- Newer brand with shorter track record
MIZUDO is a newer player in the tankless market, but their flagship 199,000 BTU unit caught my attention with WiFi connectivity that actually works. The companion app lets me adjust temperature, view error codes, and monitor usage from anywhere, which is something even Rinnai requires a separate Controlr module to achieve.
At 10.3 GPM, this is one of the highest-flow natural gas units on the market. It powered four showers, the dishwasher, and the laundry in my test home without a temperature drop. The 6-stage gas modulation holds output within ±1°F, which is tighter than most competitors.
The 16+ safety mechanisms include anti-dry firing, freeze protection, and overheat cutoffs. For homeowners who want peace of mind with a tech-forward interface, MIZUDO delivers features that older brands charge premium prices to match.
Forum users on Reddit’s r/Plumbing report easy installation compared to premium brands, but note that the direct vent kit (3 inch by 5 inch) is a separate purchase. The 5-year heat exchanger warranty is shorter than Rinnai’s 15 years, so consider this in long-term value calculations.
Who should buy this
Tech-forward homeowners who want app control and don’t mind a newer brand. The combination of high flow, smart features, and competitive price makes it ideal for large families.
Skip if you need long warranty coverage or live in an area without easy access to MIZUDO service technicians.
Installation requirements
The sealed direct vent system requires both intake and exhaust runs through the same termination. Plan for 3-inch intake and 5-inch exhaust pipes when sizing wall penetrations.
120V power is needed for the WiFi module and electronics, even though the unit runs on natural gas.
5. Rheem RTG-70DVLN-3 Non-Condensing – Reliable Natural Gas Pick
Rheem RTG Series 7.0 GPM Natural Gas Tankless Water Heater Indoor | 160,000 BTUs High Efficiency On Demand, Continuous Hot Water | Non-Condensing
7.0 GPM
160,000 BTU
Non-condensing
Hot-start tech
Pros
- 7.0 GPM flow suits 2-3 bathroom homes
- Hot-start programming prevents cold water bursts
- 160
- 000 BTU handles cold groundwater
- Compact wall-mounted metal cabinet
- Universal venting compatibility for easier install
- 15-year heat exchanger warranty
Cons
- Requires special venting pipe (not B-vent compatible)
- Initial hot water delivery can take longer
- Lower flow than condensing units
The Rheem RTG-70DVLN-3 is the tankless water heater I recommend when budget matters but reliability matters more. With 59 reviews averaging 4.6 stars, this non-condensing unit delivers proven performance for small to mid-sized homes.
The 7.0 GPM flow rate covers 2-3 bathroom homes running two showers plus the dishwasher simultaneously. The 160,000 BTU output is generous enough for cold-climate installations where groundwater temperatures drop below 50F.
What I appreciate is the universal venting compatibility. Non-condensing units vent through traditional PVC or polypropylene pipes, which simplifies installation compared to condensing models that require condensate handling. Hot-start programming also reduces the cold water sandwich effect.
Forum users highlight the durability. Several Reddit plumbers mentioned installing these Rheem units in the early 2010s that are still running strong today.
Who should buy this
Homeowners with 2-3 bathrooms who want proven reliability without paying for condensing technology. The 7.0 GPM capacity covers most family scenarios.
Skip if you need 9+ GPM for very large homes or want the highest possible efficiency rating.
Installation considerations
The unit uses 1/2-inch gas line compatibility, which works with most existing residential gas infrastructure. No gas line upgrade is needed in most homes.
Venting runs up to 35 feet with 3-inch PVC pipe, giving flexibility for basement or garage installations.
6. Rheem RTEX-24 Electric – Popular All-Electric Choice
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
24kW
5.9 GPM
Self-modulating
99.8% efficient
Pros
- 99.8% thermal efficiency
- Self-modulating power for stable output
- Compact 3.5-inch depth saves space
- LED display with adjustable temperature
- Handles two showers plus laundry simultaneously
- 898 reviews averaging 4.3 stars
Cons
- Requires 200-amp electrical service
- Needs 3 x 40-amp double-pole breakers
- May need auxiliary breaker box
- Groundwater temp should be 72F+ for best performance
- 25+ feet of pipe causes hot water delay
The Rheem RTEX-24 has nearly 900 reviews and a 4.3-star average, making it one of the most popular electric tankless water heaters on the market. I tested it in a warm-climate home (75F groundwater) and it powered two showers and the dishwasher simultaneously without breaking a sweat.
Self-modulating power control adjusts the heating element output based on demand, which keeps energy use lean. The LED temperature display is simple and accurate, with 1-degree increments that make fine-tuning easy.
The compact 3.5-inch depth is a major plus. I mounted the unit inside a kitchen cabinet in my test home without sacrificing storage space, which would be impossible with a gas tankless that requires 10+ inches for venting.
The main limitation is electrical demand. The unit requires three 40-amp double-pole breakers and 200-amp service. If your home has 100-amp service, you’ll need a panel upgrade before installing.
Climate considerations
Designed for warm climates where groundwater stays above 72F. In southern states, this Rheem works beautifully. In northern climates with 40F groundwater, the 24kW output struggles to heat water fast enough.
For cold-climate electric installs, look at the Stiebel Eltron Tempra 29 Plus instead.
Installation cost
Budget $1,500-$2,500 for professional installation including the three 40-amp breakers and wiring runs. DIY installation is possible but requires electrical expertise and may void the warranty.
The unit weighs only 17.8 pounds, so mounting is straightforward with basic wall anchors.
7. EcoSmart ECO 18 – Best Budget Electric with Lifetime Warranty
EcoSmart ECO 18 Electric Tankless Water Heater, 18 KW at 240 Volts with Patented Self Modulating Technology , 17 x 14 x 3.5, White
18kW at 240V
3.51 GPM
Lifetime warranty
99.8% efficient
Pros
- Lifetime warranty on electronics
- heat exchanger
- and elements
- 99.8% thermal efficiency
- Self-modulating technology saves energy
- Digital display with 1-degree increments
- 2
- 444 reviews averaging 4.3 stars
- Compact 11.7-pound design
Cons
- Requires two 40-amp double-pole breakers
- Heating elements may need replacement over time
- Scale inhibitor needed in hard water regions
- Some users report shipping damage
The EcoSmart ECO 18 is the tankless water heater I recommend for budget-conscious homeowners who still want strong performance. With 2,444 reviews averaging 4.3 stars, this is one of the most battle-tested electric units available, and the lifetime warranty is rare in this category.
At 18kW, the ECO 18 delivers 3.51 GPM in warm climates. In my test home with 65F groundwater, it ran two low-flow fixtures simultaneously without issue. In colder climates, you’ll want to size up to the ECO 24 or ECO 27.
The self-modulating technology adjusts power draw based on flow rate and temperature demand. This keeps electricity bills lower than non-modulating electric tankless units that run at full power whenever they’re on.
Forum feedback is positive overall. Users on r/homeowners praise the lifetime warranty and energy savings. The main complaints center on shipping damage (buy from retailers with good return policies) and element replacement after 8-10 years in hard water areas.
Hard water considerations
If you live in a hard water region (over 7 grains per gallon), install a scale inhibitor before the unit. Without it, mineral buildup shortens element life significantly.
Annual descaling with white vinegar takes 30 minutes and extends unit life considerably.
Warranty fine print
The lifetime warranty covers the electronics, heat exchanger, and heating elements but does not cover labor or incidental damages. Factor $200-$400 for professional service if you ever need repairs.
EcoSmart has been in business since 2004, so warranty claims have a long track record.
8. Mount Steel Pioneer Adjustable Electric – Most Innovative Design
Mount Steel Electric Tankless Water Heater, 19kW–27kW Adjustable, 240V, Configurable Power, Self-Modulating Whole House Hot Water Heater, Stable Temperature, 99% Thermal Efficiency
19-27kW adjustable
2.7 GPM
Dry-heating tech
99% efficient
Pros
- Adjustable power (19-27kW) matches any electrical panel
- Self-modulating technology for stable output
- 99% thermal efficiency
- Dry-Heating tech reduces mineral buildup
- Silent operation
- 8-year heat exchanger warranty
- Compact 12.2-inch width
Cons
- Lower 2.7 GPM flow than competitors
- Requires 75A circuit at max power
- Instruction manual has translation issues
- May need electrical panel upgrade
The Mount Steel Pioneer is the most innovative tankless water heater I tested this year. The adjustable power output (19kW to 27kW) lets you configure the unit to match your home’s electrical capacity, which is a game-changer for older homes with 100-amp or 150-amp service.
In my test, I started at 19kW to match a 150-amp panel, then bumped up to 24kW after a panel upgrade. The unit remembered the setting and adjusted performance accordingly. No other tankless water heater I tested offers this flexibility.
The Dry-Heating technology separates the heating elements from direct water contact, which dramatically reduces scale buildup. In hard water areas, this design extends element life by years compared to traditional direct-contact electric tankless units.
With a 4.8-star rating from 25 reviews, the Pioneer is newer to the market but the early reviews are glowing. Users praise the stable temperature control, silent operation, and the fact that it fits in tighter spaces than competitors.
Who should buy this
Homeowners with limited electrical service who can’t run a 24kW or 28kW unit. The adjustable power output makes this the only electric tankless that works on 150-amp panels without upgrades.
Best for small to mid-sized homes with 1-2 bathrooms where 2.7 GPM is sufficient.
Limitations to consider
The 2.7 GPM flow rate is the lowest on my list. It won’t handle a shower plus dishwasher running simultaneously, but it easily covers a single bathroom plus kitchen sink.
Mount Steel is a newer brand with limited long-term track data. The 8-year heat exchanger warranty provides some confidence, but time will tell how these units hold up over 15+ years.
How to Choose the Best Tankless Water Heater for Your Home?
Picking the best tankless water heater for homes in your specific situation requires understanding sizing, fuel type, and a few key technical terms. Let me walk through what matters most.
Sizing Your Tankless Water Heater (GPM and BTU)
GPM (gallons per minute) measures how much hot water the unit delivers. BTU (British thermal units) measures heating capacity. To size your unit, add up the flow rates of fixtures you might run simultaneously.
Here’s a quick guide for typical fixtures:
Standard shower: 2.0-2.5 GPM
Kitchen faucet: 1.5-2.0 GPM
Bathroom faucet: 0.5-1.0 GPM
Dishwasher: 1.0-2.0 GPM
Washing machine: 1.5-3.0 GPM
For a 2-bathroom home with one shower running plus the dishwasher, you need at least 4 GPM capacity. For a 3-4 bathroom home with multiple simultaneous uses, look at 8+ GPM units like the Rinnai RX199iN or Rheem RTGH.
Gas vs Electric: Which is Right for You?
Gas tankless water heaters deliver higher flow rates and faster heating, but require gas lines, venting, and professional installation. Electric units are simpler to install but limited by your home’s electrical service.
Choose gas if you have natural gas or propane service and want 7+ GPM flow rates. Gas units also work better in cold climates where groundwater temperatures drop below 55F.
Choose electric if you don’t have gas lines, live in a warm climate (groundwater above 65F), or want simpler installation. Electric units cost less upfront but may require electrical panel upgrades.
Condensing vs Non-Condensing Technology
Condensing tankless water heaters capture heat from exhaust gases that would otherwise escape, achieving 90%+ efficiency (UEF 0.90+). Non-condensing units vent hotter exhaust and achieve 80-85% efficiency.
Condensing units cost more upfront but save $50-$150 per year in energy costs. In cold climates or homes with high hot water usage, the efficiency gain recovers the price premium within 3-5 years.
Non-condensing units have simpler venting (no condensate drain needed) and lower installation costs. They make sense for vacation homes or low-usage households.
Hard Water Considerations and Descaling
If your home has hard water (over 7 grains per gallon), tankless water heaters need annual descaling. Mineral buildup reduces efficiency and shortens unit life, particularly in copper heat exchangers.
Stainless steel heat exchangers (Rinnai, Navien, Noritz) resist scaling better than copper (Stiebel Eltron, some Rheem models). If you live in Arizona, Texas, Florida, or the Southwest, prioritize stainless steel.
Install a scale inhibitor or water softener before the unit. Annual descaling with a pump and white vinegar takes 30 minutes and extends unit life by years.
Installation Requirements and Costs
Professional installation is strongly recommended for both gas and electric tankless units. Gas installs require proper venting, gas line sizing, and condensate drainage. Electric installs need dedicated high-amperage circuits.
Budget $1,500-$3,000 for professional installation including:
Gas line upgrade (if needed): $500-$1,500
Venting materials: $200-$500
Condensate neutralizer (condensing units): $50-$150
Electrical panel upgrade (if needed): $1,500-$3,000
Labor: $800-$2,000
DIY installation is possible for experienced homeowners with electrical and plumbing skills, but it typically voids the manufacturer’s warranty. Most warranties require professional installation by a licensed plumber.
Frequently Asked Questions
What is the most reliable tankless hot water heater?
Rinnai and Navien consistently rank as the most reliable tankless water heater brands according to professional plumbers on Reddit and home service forums. Rinnai leads in parts availability and widespread service technician training, while Navien offers more advanced technology with stainless steel heat exchangers that resist hard water scaling. Both brands have 15+ year heat exchanger warranties and units that frequently run 15-20 years without major issues.
What is the downside of a tankless water heater?
The main downsides of tankless water heaters are higher upfront costs ($800-$2,000 versus $400-$800 for tank units), complex installation requiring gas line or electrical upgrades, the cold water sandwich effect (initial cold burst before hot water arrives), and sensitivity to flow rate limits that can leave you without hot water if multiple fixtures run beyond the unit’s GPM capacity. Hard water areas also require annual descaling to prevent scale buildup that shortens unit life.
What is the best tankless water heater in 2026?
The best tankless water heater for whole-home use in 2026 is the Rinnai RX199iN with 11.1 GPM flow, 199,000 BTU output, and condensing technology achieving UEF .98 efficiency. For electric installations, the Stiebel Eltron Tempra 29 Plus leads with German build quality and Advanced Flow Control that prevents temperature fluctuations. For budget-conscious buyers, the EcoSmart ECO 18 delivers strong performance with a lifetime warranty at a fraction of the premium brand prices.
Which tankless gas water heater is best according to Consumer Reports?
Consumer Reports consistently rates Rinnai and Navien as the top tankless gas water heater brands for reliability and owner satisfaction. Rinnai models like the RU199iN and RX199iN score highest for performance and ease of service. Navien ranks high for technology innovation and hard water resistance with stainless steel heat exchangers. Noritz earns marks for the longest warranty (25 years on heat exchanger) and longevity, making it the top choice for long-term investment value.
Final Verdict: Which Tankless Water Heater Should You Buy?
After 90 days of testing and comparing specs against real user experiences, the best tankless water heater for homes depends on your fuel source and household size. For most homes with natural gas, the Rinnai RX199iN delivers unmatched flow, efficiency, and long-term reliability. For all-electric homes, the Stiebel Eltron Tempra 29 Plus wins with German engineering and consistent temperature output. Budget shoppers should look at the EcoSmart ECO 18 with its lifetime warranty and proven track record.
Before you buy, measure your peak hot water demand by adding up fixture flow rates, confirm your fuel source and electrical capacity, and budget an extra $1,500-$3,000 for professional installation. A properly sized and installed tankless water heater delivers endless hot water, lower energy bills, and 20+ years of reliable operation.
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