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Eccotemp FVI-12-NG Tankless Water Heater Review


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The Eccotemp FVI-12-NG tankless water heater is an indoor unit designed to service households with small-to-medium hot water needs. It uses natural gas as a fuel source and is capable of effectively delivering hot water to homes where more than 1 hot water application is used at the same time, such as a shower and a faucet.

Eccotemp offers both a natural gas and liquid propane version of the FVI-12 model, this gives the homeowner the option to select the fuel source that best meets their individual needs.

Eccotemp FVI-12 Review

​Eccotemp Systems, LLC is an American company founded in 2004 by Mike Elrod, with the goal to deliver "a state of the art tankless unit at an affordable price point."

The company's mission is to deliver a "whole house tankless water heater to the homeowner for the same price as a standard water heater." ​

We have found Eccotemp to be very responsive to customer inquiries thru the chat option on their website, as well as by email. 


EccoTemp FVI-12-NG Key Features

The FVI-12-NG has a lot going for it, especially for the price! Here are a few of the key features you'll find on this unit:

    Separate Controls - Both the gas pressure and the water temperature can be regulated separately.
    Precision Adjustments - Both the temperature and the water flow can be adjusted to an exact setting.
  • Digital Display - Displays the temperature of outgoing water.
    Vent Kit Included - A stainless steel horizontal vent kit is included. However, a vertical kit is available if needed.
    Ignition - Electronic ignition system ensures that the unit uses gas only when heating water.
  • Power Ventilation - Improves safety and efficiency.
  • Water Fittings - True 1/2" NPT water fittings are used.



4.0 GPM Gallons Per Minute
79 % Efficiency
74500 BTU British Thermal Units

The FVI-12 is not a powerhouse of water heater, but if your hot water needs are low this can be a nice unit, especially for the price. According to the Eccotemp website, this unit can achieve a maximum flow rate of 4.0 GPM with a 45° Fahrenheit temperature rise. However, the Amazon page lists the flow rate at 3.5 (and 3.6) GPM.

The unit will need to be installed near a standard household 120-volt outlet as it'll use electrical power to operate the internal exhaust fan and digital display. It'll pull 10 watts when operating and 2 watts when idle.

We contacted Eccotemp directly to find the minimum activation necessary for the tankless to operate. They provided the following answer:

The FVI-12-NG "is not a flow based unit, it is a pressure triggered unit. If you cannot achieve and maintain adequate water pressure, your water heater will not function properly or not at all. You need to have a minimum of 40 pounds per square inch (psi) of water pressure to activate and sustain operation of the unit."

FVI-12 Overview



A 2-year limited warranty covers the heat exchanger and other parts of the Eccotemp FVI-12, provided that the unit is installed and operated according to the company's guidlines.

It should be noted that Eccotemp recommends flushing the unit every 3-months to prevent lime scale build-up. Failure to do so may void the warranty.


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Pros and Cons

Here's a look at the pros and cons of the Eccotemp FVI-12-NG.


  • Vent Kit included
  • Low price
  • Electronic Ignition
  • Small, compact tankless unit with a modern, sleek design


  • Manufacturer recommends flushing every 3 months
  • Efficiency rating of 79%, which is very low for gas tankless water heaters
  • No internal freeze protection


Eccotemp FVI-12 Value

This no frills tankless water heater has a sleek, modern design, and the low entry price  makes it affordable for nearly every budget.

The Eccotemp FVI-12 comes with everything you need, including the horizontal stainless steel vent kit, and 110 volt UL listed power cord. 

Eccotemp promotes this unit as being perfect for "vacation cabins, cottages, and smaller homes." We tend to agree. This unit isn't going to be able to deliver hot water to satisfy the majority of homes on a daily basis, but in situations where it won't be overly taxed, it's definitely worth a second look.​


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A Closer Look at the FVI-12

The Eccotemp FVI-12 has two model types, one burns natural gas, and the other propane. For most households, this heater will struggle to keep up and may not withstand the demands of everyday use. However, if you own a cabin or vacation home, this heater is a nice low cost option.

    Dimensions: 25"H x 15.5"W x 6"D
  • Weight: 33 pounds
  • Venting: Power / Non-Condensing
  • Efficiency: 79%
  • Gallons Per Minute: 4.0 
  • BTU: 25,000-74,500 

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