Natural gas water heaters have been in use for several decades.

Over the years, the primary concept of heating water using natural gas has remained the same.

The only change has been in the form of new design, new technology, the user friendliness of the systems, and the total effectiveness and efficiency.

How Natural Gas Water Heater Works

A natural gas heater works almost in the same way that a propane water heater works.

A natural gas tankless water heater uses a natural gas burner built in the system for heating water as and when required.

Residential gas use in California

This is why some of the tankless heaters are referred to as instantaneous water heaters. In natural gas tankless water heater ignites as soon as the hot water tap is turned on.

The moment the water tap is closed; the burner shuts off. Most tankless heaters can provide 2-3 gallons of water per minute.

Since, this type of water heater doesn’t have any storage space hence they do not experience stand-by heat loss. This helps in reducing energy consumption by almost 20% to 30% in a household.

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In storage water heaters when the burner heats the water; it rises up because it is lighter than cold water. It then goes through a delivery pipe to its location, which could be a kitchen or bathroom faucet.

The gas burner in the heater system is controlled by a thermostat. Once hot water has left the tank it is replaced by cold water. In some of the systems, the burner also gets ignited when the water in the system’s tank drops below a pre-set temperature.

Types of Natural Gas Water Heaters

There are mainly four types of natural gas water heaters available in the market today. Here’s an insight into each type:

1. Standard Water Heater: The standard water heater is also known as the tank type natural gas water heater or the conventional model. This type of heaters are most commonly used although they are now being replaced by the tankless heaters in most households.

This type requires plumbing connections and pipe fittings to enable movement of both hot and cold water as well as natural gas. A tank type water heater has a built-in storage container, which is used for heating water as well as storing hot water for use later. The temperature of water to be heated is set using a thermostat built inside the unit.

2. Tankless Water Heater: The natural gas tankless water heater is constantly growing in popularity across the world because of the ease of use, instant hot water, and high savings on energy consumption.

This type of water heater is considered to be highly efficient. Considered as a technological leap; the tankless water heaters have twice the lifespan of a conventional water heater.

3. Combo Water Heaters: These are basically a mix of two types of heater: water heating and space heating. It is more of a multi-purpose heater. This type of water heater is perfect for small homes with compact space and for households where daily requirement for hot water is less.

4. Hydronic or boiler system: This is the fourth type of natural gas water heating system and is again a multi-purpose system. This type of system like combo water heaters can be used for both heating water and space heating.

The only difference is that it consists of a separate storage tank for keeping hot water and it consists of a boiler system. This type of system is also known as indirect water heaters.

Salient Features

The natural gas water heaters have several salient features like:

  • Natural gas tankless water heaters are available with Energy-Star certifications. This simply means that by using the heaters, households can actually save as much as 50 percent on their energy bills vis-à-vis conventional water heater.
  • Natural gas water heaters promote a healthy environment as their carbon emissions are much lower than any conventional water heater.
  • All natural gas water heaters need to have outdoor ventilation, which helps in reducing harmful byproducts of combustion. The most common vent type is the atmospherically vented.
  • These water heaters have longer year life expectancy and very less or no maintenance.

The Top 2 Models of Natural Gas Water Heaters


Rinnai R94LSi
Price: $1,484

The Rinnai R94LSi is a top of the line natural gas water heater, which offers continuous supply of hot water through multiple faucets or outlets simultaneously.

It comprises of a newly designed state-of-the-art heat exchanger, which has been made using commercial-grade materials only. This system also consists of a condensate collector and can be installed in high altitude places.


  • Gas Consumption: Maximum (199,000 btuh) – minimum (15,000 btuh)
  • Hot water capacity: 9.4 Gallons per minute
  • Range of Capacity: 0.7 to 6 gallons per minute
  • Energy Factor: .82

Navien NR-240A (CR-240A)
Price: $950

This natural gas water heater is considered as one of the best in the market as it has several unique features.

Considered as a 98% efficiency heater; the unit consists of buffer tank, re-circulating pump, and leak detector.

It is also available with a remote control. Another smart feature is that the heat exchangers of NR-240A have been made using dual stainless-steel, which is 20 times stronger and resistant to damage from erosion and condensation.


  • Gas Consumption: Maximum (199,000 btuh) – minimum (17,000 btuh)
  • Energy Factor: .95
  • Temperature Range: 1000 – 1400F
  • Minimum flow rate: 0.5 gallons per minute
  • Installation type: Indoor wall hung

Some of the other top brands of natural gas water heaters include Bosch, Noritz, and Rheem.

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