Flow-Rate

• Tankless heaters heat water based on flow rate, so if you're using more than one application (shower and dishwasher), it won't be as hot, but the heat is continuous. until it turns off.
  
  

Installation Location

• You can install tankless hot water heaters where the hot water is needed or as a supply for the whole house. For instance, small units can be installed near the sink or bathroom and serve only that room.
  
  

Gas or Electric

• Tankless water heaters use either a gas burner or an electric element to heat water as it flows through the heater. The flow rate for a gas heater is higher.
  
  

Cost Savings

• Energy savings versus higher installation costs will produce cost-savings over a regular water heater after 13 years, according to the American Council for an Energy-Efficient Economy.
  
  

Popular in Europe

• On-demand hot water heaters are popular in Europe in kitchens and bathrooms. They're still catching on in the U.S.