Tankless water heaters have moved well past the point of being a niche upgrade. They're standard equipment now in new construction and one of the most requested replacements when an old tank finally fails, and the lineup of available units has grown to match that demand.
Efficiency ratings have climbed enough in the last few years that a 0.90+ UEF is no longer a premium feature, it's close to standard on condensing models. What used to separate a good unit from a great one, built-in recirculation, dual fuel compatibility, outdoor-rated venting, is now showing up across a much wider range of price points. That's made the shopping decision less about chasing the highest efficiency number and more about matching a unit to the specific job it needs to do. Four models stand out from our current lineup for exactly that reason.
Why Tankless Still Makes Sense in 2026
A standard tank water heater spends most of its life keeping forty or fifty gallons hot just in case someone turns on a faucet. That standby loss adds up fast on a utility bill. A tankless hot water heater skips that step entirely. It fires up only when a fixture calls for hot water, which is why a high efficiency tankless water heater can carry a Uniform Energy Factor (UEF) north of 0.90 while a comparable tank unit sits well below that.
There's also the space question. Tank heaters eat up a corner of a basement or utility closet for their entire service life. A tankless unit mounts to a wall and takes up roughly the footprint of a suitcase, which frees up real square footage in smaller homes or tight mechanical rooms.
💡 Pro Tip
If you're still weighing the decision itself, our full breakdown of the pros and cons of switching to tankless covers installation cost, flow rate limitations, and maintenance in more depth.
How to Size Your Tankless Water Heater
Two numbers matter more than any brand name: flow rate and temperature rise.
Flow rate is measured in gallons per minute (GPM), and it tells you how much hot water a unit can deliver at once. Add up what you'd realistically run at the same time, a shower plus a dishwasher plus a kitchen faucet, and that's your target GPM. Most single-family homes land somewhere between 5 and 8 GPM, though a house with a multi-head shower system or several bathrooms running simultaneously will need more.
Temperature rise is the gap between your incoming cold water temperature and the hot water temperature you want out of the tap. If your groundwater comes in around 50°F and you want 120°F at the faucet, that's a 70°F rise. Every tankless unit's maximum flow rate drops as the required rise increases, so a heater rated for 11 GPM at a 35°F rise won't hit that same number in a cold-climate winter. Manufacturer spec sheets list flow-versus-rise curves for exactly this reason, and it's worth checking them against your climate before buying.
Homes with unusually high demand, custom showers with multiple heads, in-law suites, or large families in older houses with long pipe runs, sometimes need two units installed in parallel rather than one oversized heater.
💡 Pro Tip
For a full walkthrough, we cover sizing methodology in more detail in our tankless water heater buying guide.
Top Tankless Water Heaters of 2026
Noritz EZTR75-NG: Best for an Easy Tank-to-Tankless Retrofit
The biggest headache in most tankless conversions isn't the unit itself, it's the piping around it and adding an outlet. Swapping a bulky 75-gallon tank for tankless usually means running new PVC venting through an exterior wall and upsizing the gas line, which turns a simple swap into a multi-day job.
The Noritz EZTR75-NG is built specifically to skip that. Its top-mounted water connections line up with where a traditional tank's connections already sit, and the included N-Flex Kit lets it vent through an existing B-vent chimney using flexible 2-inch polypropylene venting instead of a full rework. For a homeowner or contractor replacing an old 75-gallon tank without wanting to touch the wall, that's the difference between a same-day install and a multi-day one.
Performance-wise, it's rated for a 0.96 UEF and delivers up to 11.1 GPM, with output equivalent to a traditional 75-gallon tank. It runs on direct electronic ignition with no standing pilot, includes a remote thermostat with preset temperature options, and connects to the Noritz Connect app for wireless diagnostics and maintenance reminders. The 316L stainless steel construction is built to resist corrosion and scale, and it carries a 5-year parts and 12-year heat exchanger warranty.
Rinnai RX Series (RXP199IN): Best All-Around Pick
If you want one unit that handles nearly any residential setup without compromise, the Rinnai RX Series RXP199IN is the one we'd point most people toward. It's a 199,000 BTU condensing unit rated at 11.1 GPM, and it runs on either natural gas or propane using Smart Sense gas valve technology, so there's no separate conversion kit needed if your fuel source ever changes.
What sets it apart is flexibility. It installs indoors or outdoors, supports 2-inch venting runs up to 75 feet, and comes with a built-in 4-speed DC recirculation pump. That Smart Circ system learns a household's hot water usage patterns over time and can deliver near-instant hot water at the tap without a dedicated return line. It's Energy Star 5.0 rated with a 0.98 UEF, among the more efficient units on the market, and it pairs with the Rinnai Central App over Bluetooth for setup, diagnostics, and quick system flushing.
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Rinnai RE Series (RE199IP): Best Value Pick for Propane Homes
Not every home needs a condensing unit with a built-in recirculation pump, and not every budget wants to pay for one. The Rinnai RE Series RE199IP is a non-condensing, liquid propane unit built for small to medium homes, remodels, and installations where a simpler concentric vent makes more sense than routing PVC.
It's compact enough to install in non-traditional spaces like crawl spaces and attics, and it's Wi-Fi ready with the optional control-r module. At a 0.82 UEF, it won't match the efficiency numbers of a condensing model, but for a smaller household or a secondary property where propane is already the fuel of choice, it delivers reliable on-demand hot water at a lower upfront cost.
Noritz NRCB199DV-NG: Best for Combined Hot Water and Heating
Some homes don't just need hot water, they need a heating solution too, and running two separate systems means two appliances to maintain, vent, and eventually replace. The Noritz NRCB199DV-NG is a combination boiler that handles domestic hot water and space heating from a single wall-mounted unit, and it can do both at the same time without a noticeable drop in either.
That simultaneous capability matters more than it sounds. In a lot of combi systems, running a shower while the heat is calling for warmth means one or the other suffers. This unit uses three separate 316L stainless steel heat exchangers, primary, secondary, and a flat-plate exchanger dedicated to domestic hot water, so each function draws from its own source rather than competing for the same one. It's rated for a 95% AFUE, delivers up to 11.1 GPM for domestic use, and includes a built-in outdoor reset control that adjusts heating output based on outdoor temperature for better efficiency through the shoulder seasons.
Note: It's an indoor, wall-mounted install only, and it's worth having a contractor confirm your home's heating load before sizing this one.
Tankless Water Heater FAQ
Are tankless water heaters worth it?
For most households, yes. The upfront cost is higher than a tank system, but eliminating standby heat loss and getting a unit that can last 20 years or more usually pays that difference back over time, especially in homes with consistent daily hot water use.
What size tankless water heater do I need?
It comes down to your peak simultaneous GPM demand and the temperature rise needed for your climate. A single-family home typically needs 5 to 8 GPM, but larger households or homes with high-flow shower systems may need more, sometimes through multiple units installed in parallel.
If you need help sizing a tankless water heater before you buy, the team at Plumbing Deals can help! Use the live chat feature, send an email to contact@plumbingdeals.com, or call 888-682-5956!
Which brands of tankless water heaters are the most reliable?
Rinnai and Noritz are two of the most established names in the tankless space, both known for durable stainless steel heat exchangers and strong warranty coverage. The right choice between them usually comes down to venting setup, fuel type, and whether you need features like integrated recirculation.
Do tankless water heaters run out of hot water?
Not in the way a tank does. A properly sized unit delivers hot water continuously as long as demand stays within its rated flow rate. If demand exceeds that rate, like multiple showers and a dishwasher running at once, the unit will still supply hot water but may not keep pace with every fixture simultaneously.
What maintenance does a tankless water heater need?
An annual descaling flush is the biggest one, especially in hard water areas, along with checking inlet filters and venting for buildup or blockage. Depending on the unit in your home, it’s also important to replace the media in the condensate neutralizer from time to time. Most modern units will flag error codes for anything that needs attention before it becomes a bigger issue.
Choosing the Right Fit
The best tankless water heater isn't the one with the highest BTU rating on the box. It's the one that matches your home's flow demand, fuel setup, and installation constraints. A retrofit-friendly unit solves a completely different problem than a combi boiler, even though both are technically "tankless."
If you're not sure which of these four fits your situation, our customer service team can walk through sizing and venting requirements with you directly. You can reach us through live chat, by emailing contact@plumbingdeals.com, or by calling 888-682-5956!
