What are the disadvantages of Tankless Water Heaters?
Higher initial cost is probably one of the biggest disadvantages, but when you think of that you are pre-paying 40% of your hot water gas bill for the next 30 years, the cost is well worth it. Also, tankless water heater are not good for homes with anemic hot water pressure, because, at full flow rates, they drop around 10 psi on the hot circuit. With most modern homes this is no problem.
