Pros: A tankless water heater is more efficient and uses less energy than a conventional water heater, providing a $25 to $107 in annual savings. If your hot water use is low (less than 41 gallons per day), a tankless water heater will be 24% to 34% more efficient.
Cons: A tankless water heater can only heat so much water at a time. If you demand more hot water than the unit can generate—for instance, if you run the dishwasher, washing machine and shower at the same time—the temperature of the water will fluctuate since the heater is trying to provide for all three locations at once
