Heating water is a big drain on your energy bill and some producers of tankless heaters say that by switching it is possible to cut your energy costs in half. Tankless heaters are also called demand of instantaneous water heaters as they provide hot water only when it is needed.
Tankless units work by quickly heating water through a heat exchanger. A gas tankless water heater is actually much more efficient then a gas fired storage tank but the savings are actually not that great as you still use gas to heat the exchanger. Electric tankless devices can be used for outdoor sinks, remote BBQ, poolhouse, pool shower, hot tubs, remote bathrooms or as a booster for solar heating, dishwashers and sanitation.
Tankless water heaters have two different fuel requirements. It is possible to purchase a gas tankless water heater or an electric tankless heater. You need to endure that your house meets the requirements for whichever type of tankless unit you chose. An electric model will have different voltage; amperage and you will need it to be on its own circuit breaker. A gas model will require gas ventilation.
An important consideration is what you want the tankless water heater to do. Is it only require for one sink or do you want it to provide enough energy for your entire house. Some single point tankless models available include the Chronomite Instant Flow SR, Stiebel Eltron Point of Use, and Eemax Single Point. A flow controlled tankless water heater is good for two water fixtures, such as two sinks. A thermostatic tankless model boosts the water temperature for long pipes that may connect to your sanitation or dishwashers.
Some larger tankless heaters that can service your entire house and have multiple fixtures include the Eemax EX280T2T series Three, Stiebel Eltron Tempra, and Rheem Indoor Gas fired flush a tankless water heater. There are even larger units that can also service outdoor areas as well as the entire house.
AS with many energy efficient products the upfront costs are high but the actual cost of running a tankless device is much less then a traditional heater system, so you will eventually break even. Tankless models require a few electrical outlets nearby to power the fan and electronics and if you have an older home you may need to upgrade your ventilation and gas pipes. Tankless units should also be flushed with vinegar once a year to break down any calcium build up. You may need additional filters depending on the type of water in your area.
There are some disadvantages to the units in that the temperature of the water is inconsistent. If you only need a trickle of warm water then there is a chance that the heat exchanger will not turn on and heat the water. It also takes some time to heat up, so tankless systems do not always provide immediate hot water. Since many tankless systems are electric you will not have hot water if the power fails.