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Tankless water heater

Installed Tankless Rinnai unit on the wall
Equivalent Hot water tank

Thery are also called on demand hot water heater or instantaneous hot water heater(of course it is not really instantaneous like conventional water heater), as the water needs to warm up by the heat source such as gas or electricity(electrically heated tankless water heater takes longer than gas). Nowadays almost all western European countries use tankless water heater

There are few advantages/disadvantes of tankless water heater over conventional water heater

  1. Endless water heater, meaning unlike hot water tank which is bound to get cold when consumption is too much over a given period of time, for example hot tub, or Jacuzzi
  2. Efficiecny, Conventional water heaters, as they have to store water in tank and keep it warm, whenever you need it, it is less efficient. The efficiency of conventional hot water heaters are from 55% to 70%
  3. there is no fluctuation of hot water temperature while using
  4. Safety: the tankless water heater are set automatically to 120 deg f, which is accurate and no chance of scalding for family members
  5. they are compact and can be installed in a limited space, while this is not possible as they are very bulky, gets bulkier with higher capacity of water(thus less efficiency as it has to keep all the water warm all the time)
    size matters.
  6. Eco-impact: Tankless water heaters not only reduce consumption of gases to the outside, unlike traditional water heaters, once there is a leak from the tank, has to be thrown out) they're repairable with replaceable parts

Disadvantage

  1. more expensive, almost twice as much
  2. needs to be sized properly for the house