Ask The Energy Expert: Natural Gas Tankless Water Heaters

 3 Reasons Why They Are The Best!


by: Scott Ranck

Water heating costs are second only to air conditioning costs here in Florida. There are many different ways to heat your water including standard gas and electric tank water heaters. Moving up in the electric water heating world, the heat pump water heater is their best offering. In the gas world, the tankless water heater is the best. tankless-water-heater-work1There are two different kinds of gas tankless water heaters: a standard tankless, which is 82% efficient, and a condensing model, which is 95-99% efficient depending upon the brand. I will give you three reasons why I believe for your money that the gas tankless water heater is the best you can buy. In comparing costs between different fuel sources, the experts convert everything to the cost of a million BTUs of energy. There is a formula that uses the cost per unit of energy, the efficiency of the equipment and sometimes losses from the source of the energy to the delivery at the site. The following chart shows the cost per delivered MMBTU for a variety of water heaters. You will note that both standard gas tankless and the condensing models beat all competition. The second reason is performance based. For this point, I want to focus on how tank water heaters (including the heat pump water heater) work. Let’s say you have your water heater temperature set at 120° on your 50 gallon heat pump water heater. You will get 70% of the tank size or 35 gallons of water at the temperature minus 20 degrees. So, out of your 50-gallon tank set at 120°, you will actually get 35 gallons at 100°.Tankless-Water-Heater-1 Your garden tub will hold 50-80 gallons of water. Can you say chilly bath with me? The first hour rating is the 35 gallons plus whatever the unit can reheat in the first hour. When in the heat pump mode only (the most efficient setting), it will only reheat 18 gallons. On the other hand, a gas tankless water heater has the same annual cost as the electric heat pump, plus the first hour rating is 234 gallons! The reason is the gas tankless only puts out hot water because it heats it continuously. This leads me to my final reason for saying gas tankless water heaters are hands down the best available. Gas tankless water heaters are the best because you never will have the frustration of running out of hot water. As long as you have water and gas, you will have continuous hot water. Better yet, after two showers or ten, you will have the same level of hot water. For all energy related questions, contact your energy experts at Florida Public Utilities at  Banner_FPUScott Ranck is the Conservation Program Coordinator & Energy Specialist for Florida Public Utilities. Feel free to e-mail any energy-related questions or comments to Scott at

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