Takagi T-H3S-OS-N Review – (Condensing / Natural Gas)


Takagi T-H3S-OS-N High-Efficiency Natural Gas Tankless Water HeaterTo have a tank water heater or a tankless water heater is the first choice you make when considering a new water heater to lower your energy costs. There may be a need or a cause to switch water heater types due to wanting to better conserve energy or maybe save in space. Once you decide that a tankless water heater will be the better option, there are certain types of tankless water heaters that would work best for your home or commercial property.

When selecting a tankless water heater, there are several types of electric and gas options. With either option, there are some benefits and some shortcomings. Before purchasing your water heater, you should check where you would like to place this water heater to ensure all the connections are there for easy installation. Whether you go with an electric model or decide on a natural gas water heater, going with tankless gives more flexibility as to where you can install your unit.

Takagi T-H3S-OS-N Tankless Water Heater is a 59 lbs natural gas water heater. It can work well with residential as well as commercial buildings. This water heater is highly efficient and will provide a consistent flow of hot water on demand. This particular model meets various environmental standards such as satisfying the SCAQMD rule 1146.2, which means the Ultra-Low NOx regulation is met. Using 120 volts, this tankless water heater is an outdoor unit only. With gas input of 180,000 BTU, the Takagi T-H3S-OS-N can produce enough hot water for approximately three showers in colder climate and 4 showers in warmer climates.


  • Heating Materials

    This dynamic tankless water heater can deliver endless hot water quickly due to the powerful Takagi unit. A tankless water heater heats the water as it flows through the heating system. The materials are usually commercial grade copper alloy. The heat exchanger tube does not have the typical stainless steel, but with a higher quality material you are heating water 25 times better than another, less effect material. Within this tankless water heater, the temperature ranges from 100 degrees to 140 degrees Celsius.

    The Takagi T-H3S-OS-N has more than just a top of the line heating capabilities. This tankless water heater has a smart system with computerized safety features. Being able to keep your unit operating to its best, there are safety such as:

    • Prevent freezing
    • Surge protection
    • Troubleshooting diagnostic codes
    • Prevent overheating
  • Compact and Powerful

    Takagi T-H3S-OS-N is an energy conserving tankless water heater. While it is 22” in height and weighing 59 lbs., this Takagi is compact and can go in several different spaces. The on-demand usage of this unit makes it an ideal purchase to provide a constant flow of hot water. Unlike water heater tanks that need connections in specific areas, there is a little flexibility in a tankless water heater. Gas water heaters are not as flexible in areas to install like the electric due to the need of connecting to your gas line. Specifically, the Takagi is an outdoor only unit. This may limit the places of where it can be installed, with its sleek design, it is not an eyesore to your residential or commercial property.

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  • Installation

    Deciding what type of water heater will work best for you means that you should also consider the installation process. A lot of times water heaters are installed by a novice, simply following the given instructions for the water heater. There is also the option to have professional assistance, especially if the manufacturer requires it in the product’s warranty. For a tankless water heater, the upfront cost is typically higher than if you go with a water heater tank. The Takagi model is no difference since this T-H3S-OS-N is powered from natural gas. This installation will require special venting. With the maximum BTU of 180,000 this will require a larger gas line than many may have already installed in their home.

  • Water Limitations

    Selecting the right size for your home is crucial to receiving hot water on demand. The Takagi Tankless Water Heater produces 8 gallons of water per minute. This will limit how much hot water can be used at the same time. With tankless water heaters, the water heats up as it passes through to come out your shower or faucet. Compared to a water heater tank, you would have a known set amount of hot water available. Also, you can better gauge how much the water heater can handle. This Takagi can supply hot water simultaneously to three bathrooms in warmer climates and two bathrooms in colder climates.

    When researching hot water limitations in a tankless water heater, the topic of the climate you are in will always arise. Your climate affects the groundwater which flows through the Takagi water heater and will heat the water on demand. Colder climate means that it will take longer for you to receive hot water through your tankless water heater. This downfall is not experienced with a water heater tank since water is sitting in a tank at a set temperature.

Water Hardness

The last thing to be aware of when purchasing any tankless water heater is the issues it has with hard water. Hard water does damage regardless of what type of water heater you use however with the tankless water heater there are a few issues that need to be addressed. If you are living in an area prone to hard water, there is the possibility your Takagi T-H3S-OS-N can experience these issues as well. It is recommended specifically with this brand to not use with water that has over 7 grains of hard water. The constant use of hard water in the Takagi will more than likely damage your unit causing it to be replaced way sooner than its normal life occupancy of 15 or more years. A way to combat this would be to regularly flush the water heater system.

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Wrap Up

The Takagi T-H3S-OS-N is a tankless water heater that has just a few cons however with its powerful performance, this water heater will provide a constant flow of hot water on demand. The Takagi outdoor tankless water heater prevents freezing, provides surge protection, has troubleshooting diagnostic codes and prevents overheating. This Takagi was built with quality materials that assist in providing hot water with temperatures ranging from 100 to 140 degrees Celsius.

With using quality materials such as commercial grade copper alloy, this allows for your water to quickly become heated. Even though the Takagi has normal downfalls such as water limitations and can run a high-priced installation, this unit can still provide years of solid performance if proper care is taken. If you are looking for a tankless water heater option, this Takagi is a compact yet powerful option.

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