Tankless gas water heater reviews and buying guide

NORITZ tankless gas water heater

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A gas tankless water heater uses the same heating process as the traditional tank-based gas systems. However, it does not have a storage tank, and will only heat the water when a user needs it, hence significant energy savings. 

In the storage-based systems, the hot water losses some energy during the standby period, and this does not happen in the tankless hence more on savings heating costs.

The heaters require less space while lasting much longer and providing you with unlimited hot water at any time. However, the systems are more costly than the storage-based, and some models may require an expensive vent system and an upgrade of the natural gas line. That said, the savings in energy, operational, and maintenance costs make the tankless system more cost-effective in the long term. 

How a tankless gas water heater works

Once you turn on a hot water tap, the tankless hearer draws the cold water. A flow sensor detects the water and activates the gas burner that then heats the heat exchanger.

The natural or propane gas, depending on the model, flows into the burner upon which a flame or electrical spark ignites it. The heat from the burner heats the heat exchanger, which, in turn, heats the incoming water to the desired or set temperature. Consequently, the system delivers hot water almost instantly. A vent pipe then safely exhausts the combustion gases to the outside.

Turning off the shower, sink, or another faucet, will stop the flow and the gas flame will go off, hence shutting down the heating process. As such, the heater will only operate when there is a need for hot water, and this delivers significant energy savings since there are no losses when on standby.

Benefits of tankless gas water heaters

Tankless gas heaters provide a wide range of operational, financial, and environmental benefits. These include but not limited to;

  • Provides endless hot water on demand
  • Durable with a long service life of about 20 years 
  • Higher energy efficiency and saving on heating costs
  • Less risk of water leaks since there is no storage task
  • Easy and inexpensive maintenance
  • Environmentally friendly 
  • Uses less expensive natural gas or propane for energy 
  • Flexible indoor or outdoor installation options

Disadvantages of tankless gas water heater

Despite the many benefits, the tankless systems have drawbacks such as;

  • Requires expensive stainless steel tubes for venting 
  • Requires annual servicing hence increasing operational costs
  • High up-front costs which could be almost three times that of a storage tank based heater
  • Requires good plumbing work to ensure that the water has enough pressure
  • When there are multiple uses, the budget systems will split the available hot water among the fixtures. in turn, this leads to fluctuating temperatures, inconsistent flows, and some discomfort.

Factors to consider when looking for a tankless gas water heater

There are various issues to factor in when looking for an on-demand gas water heater. Paying attention to these ensures that you acquire a system that best matches your requirements. 

While you may not get the exact features and performance per your expectations, you can settle on a product that ticks most of the boxes. The main things to look for include;

Physical dimensions or size

Space, where you want to install the system, influences the size of the gas heater that you purchase. Ideally, you should get a heater that will fit comfortably in your available or the preferred location. Generally, most gas tankless water heaters are larger than the electric models. The heaters often have an exhaust system that takes up some extra space.

Tankless gas water heater reviews

Type of fuel the heater uses

You have a choice between propane and natural gas. However, propane provides more benefits, including higher efficiency hence low fuel usage. Compared to the natural gas and electric models, propane has fewer emissions and therefore environmentally friendly.

Energy factor

A water heater with a higher energy factor (EF) is more efficient, hence delivers more cost savings. As such, a tankless gas water heater with a high EF value results in lower energy bills.


The type of venting for the tankless gas water heater is another consideration since these also differ from one model to the other. Also, the design, appearance, indoor or outdoor installation, and other factors influence the venting system.

Generally, there are two main types of venting; direct-vent and power-vent. Each of these exhausts to the outside. However, for combustion, the direct pull air from outside and will require two pipes intake and one for exhaust. On the other hand, the power vent uses the indoor air and only requires one exhaust pipe.

This brings about placement issues since a power vent requires larger rooms to provide adequate gas for combustion. Alternatively, a room with vents and an opening to bring in fresh air for combustion is also suitable.

The direct vent types do not require a large room and can be placed in a wide range of smaller spaces. 


To ensure the safety of users and the heater, it is important lookout for a model that has protection against various conditions. That said, this may also vary depending on your location, For example, anti-freeze protection is critical in areas that suffer from freezing but may not be necessary for warmer climates. Other safety features include overheating protection, surge protection, low water flow protection, high water pressure protection, etc. 

Capacity in gallons per minute 

The capacity of the hot water unit depends on your requirements. For single and low-demand applications for small families, you may consider 2-5 gallons per minute. However, if you need more hot water, you need to look for a heater that provides at least 8 gallons per minute.

The warranty period and terms

A longer warranty ensures that the manufacturer has great confidence in the product, and in case anything goes wrong, they will address the issue. Some manufactures may have some conditions to honor the warranty. For example, they insist that you must use a licensed installer. So, even if you have the skills to install the tankless gas heater, doing it by yourself will void the warranty.

Choosing the best tankless gas water heater

Other than the above features, you need to carry out proper research on the models you narrow down on. In particular, you have to pay attention to ease of assembly, mounting, and installation procedures, especially if purchasing online. Although you may have some technical skills to mount the compact heaters, some procedures, such as venting could be beyond your ability and may require professional assistance.

Another thing you need to find out is about the brand, warranty, cost, certifications maintenance, and customer support. For example, the availability of replacement parts as well as the procedure of fixing them yourself. You can check reviews from a wide range of places, including social media, YouTube, shopping websites, and other areas.

Today, there are several reliable brands in the market. However, these differ in the type of gas, size, capacity, and other features. That said, you can get a reliable water heater from established brands such as Camplux, Takagi, Rinnai. Paloma., Noritz, Eccotemp and Gasland.

Best tankless gas water heaters 

Here are some of the best gas tankless water heaters that we recommend. However, the list is not exhaustive.

Rinnai RUC98iN

The Rinnai RUC98iN is a powerful and efficient condensing gas tankless water heater. The 9.8 GPM indoor-only heater has a sleek design and easy access and uses digital control and display. It also emits very little nitrogen oxide (NOx) and therefore environmentally friendly. Additionally, the Rinnai water heater has a high Energy Factor of 0.92, hence reducing heating costs. It is also recirculation pump ready, meaning that if you enable the feature, the heater will provide hot water instantly while allowing you to save on water. An electric ignition system further reduces gas consumption compared to using a pilot light.

Another good feature of the Rinnai is the Wi-Fi capability which allows users to remotely turn the heater on or off, control the output temperature, etc. Additionally, you can use the feature to lock the temperature to ensure that other users do not change to a higher level with energy wastage.

Additionally, the Wi-Fi connectivity allows technicians to access the heater remotely, monitor performance, and carry out diagnostics. As such, a technician can identify the problem remotely and therefore come for the physical repair when prepared, hence saving your time and maintenance costs.

Rinnai RUC98iN gas tankless water heater
Rinnai RUC98iN


The NORITZ NR50OD is a lightweight indoor natural gas-based tankless water heater that delivers endless hot water on demand. Suitable for outdoor applications, the water heater has high energy efficiency with an energy factor of 0.91, hence savings on heating costs. The 120000 BTU, 5 GPM water heaters provide superior hot water delivery and energy savings. 

Further, the NORITZ water heater has very low emissions and is a good choice for indoor applications. It uses advanced carbon reduction technology to ensure the lowest NOx emission compared to other gas heaters.

It comes with a 5-years warranty on internal components, 12 years for the heater, and 1-year labor.

One of the drawbacks is the high purchase cost. 

Takagi T-H3-DV-N indoor natural gas tankless water heater

Takagi T-H3-DV-N indoor natural gas tankless water heater
Takagi T-H3-DV-N indoor natural gas tankless water heater

Takagi T-H3-DV-N is a compact, natural gas tankless water heater that delivers unlimited hot water on demand. You can install the energy-efficient and space-saving heater in various places in your house. The 199,000 BTU, 10GPM heater has several advanced digital features.

Benefits include modern design, being environmentally-friendly, and enhanced safety. Computerized features enable easy temperature control, optimized heating process, significant energy savings, and more. In safety, Takagi includes overheat, surge and freeze protection. It also has diagnostic codes that ease the maintenance procedures. 

However, it is a bit difficult to install and may require a professional installer. But once installed, the Takagi is one of the best gas water heaters. 

The ultra-low NOx emissions heater has a commercial-grade copper alloy heat exchanger, which provides superior heat transfer in addition to being long-lasting. Finally, you get a 15-year warranty in a domestic installation.

Suitable for both residential and commercial applications and can support up to three showers in warm climates.

Click here to buy it on Amazon.

Rheem RTGH-95DVLN Tankless Natural Gas Water Heater

Rheem RTGH 95DLN is a high-efficiency, direct vent natural gas tankless water heater. The 9.5 GPM, indoor-only, water heater is small and easy to install with a 12-year limited warranty. It has inbuilt electronic controls that enhance its safety and energy efficiency. The 199, 900 BTU, low NOx device has a stainless steel condensing heat exchanger, a 94% energy efficiency, and an energy factor (UEF) of 0.93. 


Other features include an inbuilt condensate neutralizer and enhanced water savings. Its low flow activation ensures hot water is available whenever required including times of low demand. Also, it has a hot start programming that reduces the cold water busts while a recirculation pump kit-ready improves water savings.

Rheem RTGH-95DVLN Tankless Natural Gas Water Heater

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Camplux Pro 26L

Camplux Pro 26L Gas Tankless Water Heater

The Camplux pro 26L is a high-capacity natural gas tankless water heater. With an impressive 6.86 GPM, the large outdoor heater is ideal for high demanding applications. The heater can meet the hot water needs of a large house while supporting up to three showers and a kitchen simultaneously. Its 180000btu/hour output power ensures that water is hot quickly almost at the instant you turn on the tap or faucet.

The easy to install with ultra-low NOx emission includes several safety features such as overheating and freezing protection, flame failure device, low water flow protection, etc. Additionally, it has a simple and aesthetically pleasing design, so you can install it anywhere. The Camplux has a 99 F to 140 F (37-60 C) adjustable temperature range.

The outdoor installation does not require venting hence fewer installation costs in pipes, accessories, and labor. It also has a detached digital control panel which you can install 3.3 feet away from the heater using the provided cable. The remote control allows you to manage the outdoor heater from inside the house.

Click here to buy it on Amazon


Tankless gas water heaters are more efficient since, unlike storage-based systems; they do not continuously heat and store hot water. Additionally, tankless systems have longer lifespans. With regular maintenance, it can serve you for between 15 and 20 years while delivering significant savings on energy, water, and overall operational costs.