Best Natural Gas Tankless Water Heater - A Complete Guide

People often get confused about choosing between tank and tankless heaters. It is definitely a very troubling decision because both tank and tankless types offer completely different advantages. Moreover, the quality of heating, speed of hot water output and consumption of energy all differ greatly in both models. This is why we have collected here all the necessary information and a comparative analysis of gas tank type and gas tankless heaters for the convenience of our customers.

Natural Gas Tankless Water Heater

Tankless Gas Water Heater

Gas tankless water heaters are the same as conventional tank type water heaters minus the storage tank. Like gas tank water heaters, these also require venting but don’t store water and heat water only when needed. This reduces the standby energy loss operation. Gas tankless heaters start heating water through the built-in heat exchangers when you turn on the tap. As the cold water draws into the heater, a flow sensor signals the gas burner to get activated and warm the heat exchanger. Incoming cold water passes through and encircles the warm heat exchangers and gets heated at the pre-set water temperature. Combusted gas exits safely via a dedicated, sealed ventilating system.

If the unit is ENERGY STAR certified that it will be equipped with a secondary heat exchanger that uses 9% less energy than a standard gas tankless water heater. This secondary exchanger extracts more heat from the combusting gas and cools it to that particular point where it gets condensed. These kinds of heaters are known as “gas condensing.” Such heaters work just like gas condensing furnaces and need venting via a vertical PVC pipe as well as a condensate drain.


Installing a Gas Tankless Unit

Gas tankless water heaters do not contain a storage tang but unlike gas tankless heaters these do require venting. The venting and combustion air supply requirements of gas tankless water heaters is quite complex specifically if you have installed it in a congested and confined space. Moreover, it is not possible to use existing gas lines and/or venting ducts for tankless units. The installation may get even more complex if the unit requires side wall venting. Gas tankless units’ gas consumption level is high whereas the currently available ventilation options are insufficient. This is why the installation of gas tankless water heaters is quite expensive and complicated.


Efficiency Analysis of Gas Tankless Heaters

The units that use heavy-duty burners so that water heats up quickly are found to be 22percent more energy efficient than traditional gas fired tank-type models. This means you can easily save around $70 to $80 annually. However, since the cost of gas tankless water heaters is higher than tank type units therefore, it might take around 22 years to compensate for the high cost and break the 20years life span of other models.


Gas Powered Tank Type Heaters

Majority of consumers prefer to use tank-style water heater. This unit heats water even when it is not required or the heater is not in use. To compensate the standby heat loss, insulation between the storage tank and the exterior jacket work slowly. To maintain desired water temperature the heater needs to cycle-on periodically even if you haven’t turned on the tap.

Generally, tank-type water heaters have around 70% usable capacity, which means a 50-gallon tank keeps approx. 35gallons of hot water in reserve. The gas water heaters that are available nowadays contain exclusive flammable vapor ignition resistant technology also known as FVIR. FVIR prevents the ignition of flammable vapors outside the unit for instance, spilled gasoline. The heat used by a gas water heater is generated from a burning fuel, which usually is natural gas.


Advantages of Tank Type Gas Water Heaters

Typical gas tank type water heaters are less energy efficient but their recover rate is faster than gas heaters. This is why gas heaters are considered more suitable for large families. Moreover, these heaters now offer efficiency of up to .94 energy factory ratings, which makes it a better choice for domestic usage in comparison to gas tankless water heaters.

As far as purchase price is concerned, conventional gas tank type and gas tankless type are similar however, in the longer run it is obvious that tank type water heaters have longer lifespan. Installation wise, gas tankless and tank water heaters both are a bit complicated to mount and maintenance cost is also higher.


Summary Table of Natural Gas Tankless Water Heaters

Heater Model

Picture

Links to Our Detailed Reviews

Buy on Amazon

4.2

Rinnai has a large selection (the ultra series) of natural gas tankless water heaters.  We have an individual review of the 9.8 gallons per minute model.  The others are similar, just with varying capacity.


4.9

4.1

Takagi also has a 6.6 GPM version available.  We have an individual review of the 10 GPM model.


4.3

As usual, there is a whole series of Rheem RTG models.  The number indicates the GPM, while the letters distinguish indoor/outdoor and natural gas versus propane.  We have an individual review of the indoor natural gas unit.  We have a whole other page on the site for propane tankless heaters.


4.1

The Rheem RTGH line differs from the Rheem RTG line in that the RTGH (the "prestige" series) is a very high efficiency condensing unit.  I believe the H stands for High-efficiency.  These cost more upfront, but save money over time.


4.6

4.1

4.0

Comparative Analysis

From the perspective of consumers, gas tank type heater is a lot cheaper option than gas tankless heater. If there is a gas line available in the house already then gas tank type heater becomes the priority because gas tankless units are a bit complicated to install. If you want to switch from gas tank to gas tankless type heater, then this can be a bit expensive since installation of a gas line and ducting/venting for heat expulsion will be a necessary drill.

The short lifespan of gas tankless heaters is another considerable drawback but the different is not that big at all. If gas tank heaters last from 15-20 years then the average lifetime of a gas tank type heater is around 10 to 15 years. If you use the heater carefully and perform service regularly then the lifespan of a gas tankless heater may also get extended.

However, we cannot deny the fact that gas is readily available and happens to be a much cheaper option for regulat usage than propane or electricity. Therefore, whether gas tank type or gas tankless type is your priority, both would be suitable for in-house use.

Thus, it can be concluded that the difference between both heater models is not humongous and each type has its fair share of pluses and minuses. You need to consider the family size, usage requirement and space readily available before selecting the water heater type. If your family is large and you think a gas powered tank type heater will prove to be a lot cheaper than go for tank type gas heater. On the other hand, if demand is low and space is congested then a compact tankless water heater would be great.