Standard Hot Water Heaters (those with a tank) heat and reheat your hot water 24 Hours a Day! A Tankless water heater only heats water when you're using it... only when you need it.
So you're only using energy (and spending money) to heat the water you use instead of heating (and spedning money) to heat water all day long.
A tankless water heater heats water without using a storage tank. When a hot water tap is turned on, cold water travels through the pipe and into the tankless water heater, which heats the water.
Bottom Line- A Tankless water heater only provides hot water as it is needed, versus a standard water heater that stores hot water - using energy and costing money.
Depending on a home's usage of water (family members, roomates, etc.), it is possible for tankless water heaters to be over extended. One of your tankless water heater options, at this point, is to install multiple tankless water heaters. Many homes install a tankless water heater at each hot water outlet - however; it is truly up to the home owner and the reccomendations of your local tankless water heater technician.
Whether you install a tankless water heater at your main cold water inlet only (recommended for smaller families) or branch out and install tankless water heaters on your major appliances (dishwashers, showers, washing machines, etc), each option is still a water saving, energy saving and ultimately money saving option.
Electirc Tankless Water Heaters contain an electrical heating unit. Electric Tankless Water Heaters will require power (voltage, amps and possibly its own circuit breaker). Some electric tankless water heaters may require their own circuit (possible more than one circuit) so it is always highly recommended to consult an electrician or local electric tankless water heater installer.
Gas Tankless Water Heaters contain a gas heating unit. Gas Tankless Water Heaters require gas (natural gas, propane, etc.). For homes without a gas line this a gas-fired tankless water heater may not even be an option; and for homes without a gas line - it is important to consult with a local tankless water heater expert to make sure that your gas-powered tankless water heater will work with your current gas line.
The last thing to consider with your gas-powered tankless water heater is the venting requirements (again, seek a professional tankless water heater installation service for more details).
Finally, regardless of whether you choose to install an electric tankless water heater or gas tankless water heater you must consider the size and location of the tankless water heater. The easiest hassle free way is to contact a tankless water heater service and have a professional trained and certified tankless water heater technician assist you in choosing the right tankless water heater.
The size and power of your tankless water heater depends mainly upon the amount of water your home uses. Often times one tankless water heater will be enough; however, if streched to thin, a single tankless water heater may fail to always product warm water. This is why many home owners decide to install multipe tankless water heaters.