Best Tankless Gas Water Heater

If you’ve ever frozen your fingertips off while waiting for hot water to come out of the faucet on a cold winter morning, you know why tankless gas water heaters are rapidly gaining popularity as one of the more energy efficient appliances.

They heat water INSTANTLY.

If you’re reading this, chances are you’re trying to decide whether or not a tankless gas hot water heater makes sense for you, and which models are the best.

The Short Answer

In a hurry to get the skinny? No problem. The best tankless water heater in our opinion is:

Rinnai RU199iN Tankless Water Heater

Why It’s Number 1:

  • Capable of a generous flow rate of 11 gallons per minute (GPM), more than adequate for a family of four with water demands on the heavy side
  • Uniform energy factor of 0.93, Qualified EnergyStar energy factor of 0.96
  • Residential warranties include: heat exchanger, 180 months; labor, 12 months; parts, 60 months

The Rinnai RU199iN Tankless Water Heater gets rave reviews all around for convenience, quality and dependability. Plus, it’s backed up by the well-established customer service practices of Rinnai, one of the most trusted names on the market.

This water heater can pretty much go anywhere due to its size. Even with all of its capacity, it takes up little space – in fact, less than the average travel carry-on case. In terms of versatility, this makes it easier to locate it between the fixtures that get the most use, allowing for hot water to reach either without delay.

As a high-capacity water heater, this unit can handle larger water demands better than most other water heaters. In fact, even a family of four can take showers, do laundry, dishes, and other household functions without a hiccup. If your demands aren’t enough for multiple units but you need more than the average unit can provide, this unit will take care of you.

Other Great Tankless Gas Water Heaters:

Rheem RTG-84DVLN Direct Vent Indoor Natural Gas Water Heater

Why People Love It:

  • adaptable to increased demands by allowing up to 20 tankless units to be tethered as one operational unit
  • digitally displays temperature and maintenance codes
  • Next Generation burner technology

This water heater works 9,840 feet above sea level. It does its own diagnostics and is programmed to display them on-screen so you can keep tabs on what’s happening at any given moment. It also has cold-weather protection down to -30°F. Its flow rate is 26 gallons/minute of non-stop hot water that never runs out.

You can set the water temperature to your specific preferences anywhere between 85°F and 140°F. For buildings that use more than one unit, the units can be tethered together to work as a team, using one control. This water heater gives great value while packing a punch.

This water heater would be great for people who love living in rugged environments.

Bosch 940 ES NG Gas Tankless Water Heater

Why People Love It:

  • intelligent cascading capacity up to 24 units
  • 15-year heat exchanger and 3-year parts warranties
  • sealed combustion with dual fans send hot air directly outside to cool

For your and your family’s safety, this member of the Bosch Therm series is ultra-low nitric-oxide-certified, meaning it doesn’t emit exhaust that will deplete the ozone in the troposphere, create smog or produce acid rain. It runs on liquid propane or natural gas, so no worries if you have either one or the other. It’s also a noncondensing model, which means that hot gases that are produced when the unit is operating are vented directly outside via non-heat-conducting materials.

This water heater is Bosch’s highest-capacity model, so it would be perfect for large families that use a lot of water and create heavy demands upon the system. It also tucks away in a small space like a closet or on a wall somewhere out of the way, so if you’re someone who lives in an economical or densely occupied space, this would be the perfect water heater to consider.

Rinnai High Efficiency 7.5 GPM 180000-BTU

Why People Love It:

  • Has built-in backup safety devices
  • Flow rate is 7.5 GPM
  • Compliant with South Coast Air Quality Management District requirements
Rinnai Tankless Gas Water Heater

The Rinnai High Efficiency 7.5 GPM 180000-BTU Gas Tankless Water Heater has an energy factor of 8.2 for either type of gas.

This unit is good for people who live in mobile homes, being that it is limited to outdoor use only. This is for safety reasons, as it operates by forced combustion.

Takagi TK-540P-NEH Outdoor Gas Tankless Water Heater

Why People Love It:

  • 15-year residential / 10-year commercial warranty, 5-year warranty on all parts except for fuses
  • Flow rate of 6.3 GPM
  • EnergyStar-listed
Takagi Tankless Gas Water Heater

Customers appreciated several things about his water heater, including quality and customer service. Although some customers said that the old Takagi heaters were the best, this model is less costly and better than others available on the market today.

This model installs easily. It just screws into the wall and connects in on the input and output lines, making it less time-consuming and costly to install. It’s excellent for families and heavy water-usage situations because not only

does it deliver plenty of hot water for everyone, it also cuts down the cost on the energy it takes to heat the water.

Most Important Factors In Tankless Gas Hot Water Heaters

A tankless gas water heater will last longer than conventional tank-type water heaters, and that’s great because it will also save you lots of money over the long term.

The water runs through a set of heat exchangers and copper piping in the interior of its relatively small size, which means that the water you use to wash your hands in will not have sat corroding the tank that contains it–a big plus in the health colum.

It requires less maintenance, can be controlled by a cellphone and will give you unlimited hot water with no “cold sandwich” to run out of the pipes before you get hot water.

A tankless gas water heater is the perfect solution for high-demand situations like those typically experienced by families with teenagers vying for the bathroom while Mom is trying to do a load of laundry. Because you can’t run out of hot water, everybody benefits without all the wailing and stomping around.

Initial Unit Cost Is 2-3 Times the Price of a Conventional Gas Water Heater

The initial outlay for a tankless gas water heater will set you back between two and three times the cost of a conventional gas water heater with a tank. For a tank-style heater you can expect to pay $1000-$2,000 for the heater + installation, a tankless unit can cost up to $6000 for heater + installation.

Why might you want to consider the extra investment? You will have a longer-lasting water heater that will relatively quickly pay for itself and give you unlimited hot water on demand. It involves lower energy costs, greater efficiency and the elimination of the corrosion issue that releases particles into the water as it sits in a tank waiting to be used.

Tankless Gas Heaters Actually Remove a Lot of Corrosive Particulates

The water that goes through a tankless gas water heater is treated well so it will come out of your faucet not only heated to your specifications, but unburdened with the residues and particulates from the corrosion that occurs over time with a conventional tank-style heater.

The best lines for this type of water heater are made of copper. It’s easy to work with and tolerates contact with hot and cold water well.

Copper is also well-known for its superior temperature conductivity, leading to faster heating. Just make sure the unit you buy is properly certified for quality-safe materials, and you’ll be enjoying it in good health for years to come.

Requirements For Installation

When you go to install one of these heaters, things to expect are:

  • Electrical installation, direct venting, and plumbing updates to route water in and out of the new unit.
  • Pressure intake and exhaust pipes require drilling a hole through the side of the building to bring the hot exhaust outside.
  • Three-quarter-inch copper lines will be installed to channel hot and cold water in and out of the unit.
  • There will be a gas line from outside leading in to the unit that will be fitted with a shut-off valve. As part of the installation, this will need to be purged and tested before the unit is used.
  • A new cold-water line, also run in from outside, will be fitted with an expansion tank to allow for water to expand as it’s heated. Cold water goes into the unit from there and comes back out hot through copper piping that connects back into the building’s plumbing system. This is also fitted with a safety valve that releases temperature and pressure if ever necessary
  • Another line coming out of the unit handles the condensate (slurry of flue product from the combination of gas combustion and condensation from the temperature differentials. The minimal remaining condensation runs through a hose from inside of the unit to a floor drain (buckets work temporarily as long as you remember to empty them).
  • At the top of the unit are the combustion and exhaust pipes.
  • And last but not least, a temperature-control thermostat is wired into the unit.

Additional options are to add a crossover valve to recirculate the “cold sandwich” water back into the plumbing to be heated and enjoyed, rather than being wasted down the drain while you wait for hot water like in the old days. We think it’s really a pretty ingenious and resourceful way to save time, water and money and well worth the cost.

Here’s How to Size Your Tankless Gas Water Heater 

When you go to buy a tankless gas water heater, you might want to go prepared by researching the different sizes to figure out which is best for you.

Here’s how:

  1. Add up the flow rates of all fixtures that could potentially be used at the same time. If you go too small, you won’t get consistent water temperature or pressure when multiple users are simultaneously using water.
  2. Then, you’ll need to figure out how many BTUs (British Thermal Units) it’ll take to heat the water. Use this formula to calculate BTUs: 500 x GPM x Temperature Change = Required Power Input in BTU per Hour

If you have further questions after going online and/or looking at actual units in person, you can always ask a good local water-heating specialist to help you identify the best size.

Remember: No Power = No Hot Water

With all of the benefits of a tankless gas water heater, there is one clear downside that doesn’t extend to tank-style systems. No water heater will work if the power goes out — unless you’ve anticipated that possibility and have already installed a backup power source.

The problem is not with the unit, nor with the gas. It lies in the sparking mechanism that ignites the gas to heat the water. This is the one area in which a tank-style water heater, with its already-warmed supply of water, has the advantage over tankless.

Even if the power goes out, the water in a tank will retain heat several days. So our advice would be, if your goal is to have a tankless gas water heater: get backup power before you need it.

Frequently Asked Questions

Do Tankless Gas Water Heaters Actually Save Money? 

To purchase the initial unit, no. In the long run, yes.  The U.S. Department of Energy estimates gas-fired tankless heaters save an average of $108 in energy costs per year over their traditional tank counterparts, while electric tankless heaters save $44 per year.

Remember however, that the cost to purchase and install tankless heaters can sometimes be significantly more.

Apart From The Cost Savings Aspect, What Are the Benefits of Going Tankless? 

In addition to long term cost savings, there are 2 major benefits:

  1. Tankless water heaters can fit on the wall or even in a closet to leave open space that a tank would otherwise be taking up.
  2. They give unlimited hot water on demand with minimal condensation issues.

What Kind of Ventilation Do Tankless Gas Water Heaters Require?

Direct outdoor ventilation is required with these units. Outdoor ventilation shunts hot gases from the unit outside to cool. This prevents the kind of condensation that can create indoor humidity issues.

Bottom Line

What’s not to love about having all the hot water you need, on demand, while saving money? And how about all the space your hot-water tank used to take up? If you can swing the cost, this unit that quickly pays for itself may be one of the best investments you can make for your home and for your peace of mind.