Tankless water heaters are ventilated in two ways.
Tankless water heater no power required.
Tankless units are susceptible to failure due to hard water.
Tankless gas water heaters have an internal pc board electronic ignition and an electronic thermostat which is required to operate the water heater.
No a tankless gas water heater still requires some electricity to operate.
Most traditional tank systems also need electricity.
Direct vent units attract outside air from the house or building while power vent units solely need an exhaust vent and should be installed in a larger area for receiving sufficient air amount for combustion.
The short answer is yes a gas tankless water heater needs electricity to work.
During power outages tankless units will not produce hot water.
In warmer climates it s easy to install a tankless water heater outdoors with no additional venting required.
Tankless units are designed to withstand below freezing temperatures through self warming capabilities that prevent freezing and cracking.
Tankless hot water systems which operate on electrical power will not function if there is a loss of power at the home.
Without a power source these components will not operate preventing the tankless water heater from producing hot water.
Tankless water heaters come in two types gas or electric.
Power vent and direct vent.
Propane or natural gas tankless water heaters that need no grid power are common in the developing world and many of those models are available in the us if you know where to look.
Many water heaters especially traditional electric ones require changes to your wiring and potentially the breaker box.
Hard water is problematic for all water heaters but especially for tankless units.
If your pilot light is fired up by your power source then you need to be on the grid.
How to determine the required size of a tankless hot water heater.
Some gas powered systems may continue to operate depending upon how fuel is supplied to the unit.
Marey a us company based in puerto rico has several decent quality models almost all imported from china that require no grid power to operate but there are others.
On average gas fired heaters are more efficient and heat the water.
In order to ensure your safety and qualification for the limited lifetime warranty a licensed professional must install your system.
Beyond a water heater permit some areas may also require either an electric or plumbing permit depending on the type of water heater.