gas water-heater tank 
Mechanism cutting off the gas supply when the water reaches the desired temperature.
Device for lowering the pressure inside the tank by releasing excess hot water.
Pipe through which water escapes when maximum pressure is exceeded.
Box containing the set of controls that measure temperature and operate the burner.
Device for emptying the water from the tank.
Metal casing protecting the tank.
Outlet pipe for hot water flowing into the hot-water circuit.
Device reducing the amount of air withdrawn by convection.
Device for setting the temperature.