Most construction pros are familiar by now with how tankless water heaters improve water-heating performance by heating on demand. But some still have questions about whether tankless water heaters will save money. In a new video for the Build Network, plumbing and heating specialist Eric Aune says the misconception may come in part because of the maximum gas inputs of tankless water heaters compared with traditional units.

In the video, Aune shows the two Navien tankless water heaters in his own home that can fire up to 199,000 British thermal units (Btus). His two previous power-vented tank-style water heaters could reach only 120,000 Btus combined. “The thing is that they were keeping hot and storing 50 gallons per tank, 24 hours per day, whether I was in or out of the house and whether I was demanding hot water from them or not,” Aune says.

While tankless water heaters are capable of using more Btus at any given time, they’re put into service only when hot water is needed, and they can modulate so that lower hot-water demands require less gas to be used. “Will they save money?” Aune asks. “I believe they do in almost every single case.” To learn more about common tankless water heater myths, check out our Myth Busters video series with Matt Risinger.

Check out Aune’s video here.