Comparing Prices of Gas and Electric Tankless Models


When comparing tankless water heater prices, you should only compare models of the same capacity. The capacity of a tankless water heater is stated in gallons per minute (gpm). It is a measure of the water heater’s ability to raise the temperature of the incoming groundwater to your desired hot water temperature. If you live in the northern parts of the US, the winter groundwater temperature can be 35 degrees lower than that in the southern states, and you will need a higher capacity water heater to serve your needs.

Unfortunately, when some manufacturers market their water heaters, they inflate the heating power by only stating their warm climate capacity. It is, therefore, important, when you compare tankless water heater prices, to compare models that have the same capacity in handling the groundwater temperatures in your area.

Electric tankless water heaters generally cost less than gas tankless water heater models of the same capacity. However, if your home has a high hot water demand, you may not be able to find a tankless electric model with a high enough capacity. This will be especially true if you live in an area where the groundwater temperatures are low.

For example, one of the highest capacity tankless electric water heaters is the Stiebel Eltron Tempra 36 ($850). This water heater will be able to serve 1 shower and 1 hand basin simultaneously with 110 degree hot water at the average US groundwater temperature of 55 degrees Fahrenheit. However, this electric on demand model will only be able serve 1 water fixture in an area where the groundwater temperature is 35 degrees. If you need a water heater to serve 1 shower and 1 hand basin simultaneously when your groundwater temperature is 40 degrees, you will either need to purchase a gas tankless water heater, such as the Noritz 0631 ($900), or, if you do not have gas lines, you could connect 2 electric models in parallel, such as the Stiebel Eltron Tempra 20 ($625). Gas tankless water heaters have much higher capacities than tankless electric water heater models.

In April of 2008, the US Department of Energy announced Energy Star criteria for water heaters.  Electric tankless water heaters do not qualify as Energy Star water heaters, but whole house gas tankless water heaters with an Energy Factor of 0.82 or higher do qualify, and are eligible for a 30% tankless water heater tax credit. This credit is applied to the purchase price of the water heater and the installation cost up to a maximum of $1,500. Local utility companies also offer rebates.

When you compare tankless water heater prices you need to also take into account the installation cost and the operating expenses.

The combustion requirements of tankless gas models are much higher than gas storage tank units. Therefore, if you are thinking of replacing your gas tank-type water heater with a tankless model, you will probably need to upgrade your gas lines to ¾ inch lines, and you will need to replace your old venting with stainless steel venting. Depending on the length of your gas lines and the location of your water heater, the cost of these upgrades can be substantial. You will, however, be able to claim a 30% tankless water heater tax credit on the cost of these upgrades.

Replacing an electric tank unit with an electric tankless model will also involve upgrades, but the upgrades will be a lot cheaper. You will need to install a 240V 200 AMP electric service, with dedicated double-pole breakers for each heating element.

Operating costs are also important when you compare tankless water heater prices. Gas is usually cheaper than electricity, but electric tankless water heaters are about 15% more efficient. Taking into account the difference in fuel costs and efficiency, gas tankless water heaters will cost about 15% less to operate than electric tankless units. The exception to this are the condensing tankless water heaters. These gas tankless units have efficiencies as high as 95% or 98%, and their operating costs will be about 30% less than tankless gas water heater models.

Below is a price price guide for various gas and electric tankless water heaters. The models are sorted according to their capacity to raise the temperature of 55 degree Fahrenheit groundwater (the average groundwater temperature in the US), to a 110 degree Fahrenheit hot water temperature. The capacity of each water heater in the price list is stated in gallons per minute and in terms of the number of fixtures it can serve simultaneously. A fixture could be a shower, bath, dishwasher, washing machine or kitchen sink with a flow rate of 2.0 to 2.5 gpm. A ½ fixture is a term that we use to describe a bathroom sink with a flow rate of about 1.0 gpm. You will notice that there are no electric tankless water heaters with a flow rate higher than 4.6 gpm for a 55 degrees temperature rise.

Compare These Gas Tankless Water Heater Prices

3½ Fixtures 
Noritz 0931 (7.6 gpm)—$1,880

3 Fixtures 
Navien CR-240 Condensing Water Heater (7.1 gpm)—$1700
Rinnai R98L (7.0 gpm)—$1,450
Takagi Mobius T-M32 (6.9 gpm)—$1,850

2½ Fixtures
Noritz 0842 Condensing Water Heater (6.8 gpm)—$1,660
Takagi Flash T-H1 Condensing Water Heater(6.6 gpm)— $2,370
Navien CR-210 Condensing Water Heater (6.2 gpm)—$1,500
Noritz 0751 (6.1 gpm)—$1,120
Rinnai 94L (6.0 gpm)—$1,340
Rheem RTG-74 (6.0 gpm)—$1,150
Bosch Aquastar 2700 ES (5.9 gpm)—$1,120

2 Fixtures
Takagi Flash T-K3-OS (5.7 gpm)—$800
Rinnai R75L (5.5 gpm)— $900
Rheem RTG-66 (5.4 gpm)—$780
Bosch Aquastar 2400ES (5.3 gpm)—$1,050
Navien CR-180 Condensing Water Heater (5.3 gpm)—$1,300
Noritz 0631 (5.2 gpm)—$900

1½ Fixtures
Rinnai R63L (4.5 gpm)—$700
Rheem RTG-53 (4.4 gpm)—$620
Noritz 0531 (4.2 gpm)—$700
Takagi Flash TK-Junior (4.2 gpm)—$600

1 Fixture
Bosch Aquastar 125 FX (3.6 gpm)—$780
Bosch Aquastar 1600H (3.4 gpm)—$660

Compare These Electric Tankless Water Heater Prices

1½  Fixtures
Eemax EX 380 (4.6 gpm)—$700
Stiebel Eltron Tempra 36 (4.5 gpm)—$850

1 Fixture
Stiebel Eltron Tempra 29 (3.6 gpm)—$750
Eemax EX280 (3.6 gpm)—$700
Bosch PowerStar AE125 (3.4 gpm)—$650
Stiebel Eltron Tempra 24 (3.0 gpm)—$650


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