Takagi T-H3J-DV-Review (Indoor Whole House Natural Gas or Propane)

Gas powered Whole house indoor tankless water heater from the Takagi line

There are two kinds of tankless water heaters on the market. The first is called a "point of use" unit, and while it offers piping hot water at whatever sink or shower it's attached to, it doesn't deliver the kind of whole-house power that you need to run multiple taps at once.

Enter the Takagi T-H3J-DV series which have both natural gas and propane units.  

As a whole house unit, it's more than capable of meeting your demands for hot water around your entire residence. A single T-H3J-DV installed anywhere on your property will deliver hot water across your kitchen and multiple bathrooms. 

But what else does this unit offer? How can you be sure it's the best unit for you?

I understand that you want to be confident in your choice before investing your money in such a major purchase, so let's take a closer look at all it does.

Check Price on Propane Unit

Check Price on Natural Gas Unit


First things first: What kind of numbers will you get with the T-H3J? There are several important ones to consider, so let's examine them one by one.

  • Flow rate: This unit offers up to 6.6 gallons per minute (GPM) depending on things like altitude and outdoor climate. If you aren't familiar with tankless water heaters, that's an average figure that you see in average-demand whole house units.
  • Power: The TH3DV can require up to 160,000 BTUs. This can produce enough hot water for two bathrooms in warmer climates or 1.5 baths in colder climates.
  • Size: At just 58 pounds, this is a pretty compact unit. Many natural gas tankless water heaters are much larger.


As previously mentioned, this is a "whole house" unit, so you'll only need to buy and install one of them to service your entire average-sized home. Its power also comes in a such a compact package that it can be placed anywhere on your property.

In terms of functionality, it heats with natural gas. 

On one hand, its internal sensors and burners are extremely efficient, so you're getting a high-quality performance there. It's has computerized safety features and has no pilot light to have to worry about.

As an indoor unit, you'll also need to install a vent to the outside to prevent its fumes from harming your loved ones. 

Heat Output and Flow

While your exact GPM will depend on where you live and how cold it is outside, you can generally expect up to 5.5-6.6 GPM.

That's a good number that can provide hot water for anywhere for 2 bathrooms and a kitchen. Customers do report slight flow delays with simultaneous usage or in climates with extremely cold temperatures.


While we always recommend that a trained technician handle the installation of tankless water heaters, this unit is relatively easy to understand and assemble, so it isn't outside the realm of possibility to DIY.

In fact, Takagi includes a detailed instruction manual for this very purpose.

Here are a few of the tools and supplies you might need for the job:

  • Vents
  • Ground lines
  • Circuit breakers
  • Electrical boxes

If you have any questions, don't be afraid to call that technician.

General Use

As with any product, there are pros and cons, so make sure you consider both lists before handing over your credit card.


  • Powerful "whole house" unit
  • Compact system that can be installed anywhere
  • Handles simultaneous usage with ease


  • May experience flow delays in cold climates
  • Above average price range

What's the bottom line?

If you're looking for a reliable whole house (average size home) tankless water heater, this Takagi model you won't want to miss.

​Though it isn't flawless, we give it a solid four out of five stars, and are confident that it can meet the needs of most homeowners.

But you don't have to take my word for it! Check out thee Propane or Natural Gas units on Amazon. Check out the Propane unit on Amazon or the Natural Gas unit to see details, specs and performance reviews by other consumers just like you.

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