The water in our apartment (department) is heated by "califacion". There are no water heaters here. It roosts on the wall in our kitchen above the sink. When we turn the knob with a "C" (C stands for Caliente, not cold) it fires up and heats the water as it passes by. It actually works pretty well.
Gas Flame below
Below is what happens when you turn on the hot water. It fires up all the burners and makes a crazy noise when you shut it off! It heats up the kitchen on a cold day and on a hot day, you just don't stay in the kitchen very long!
The pictures below are of vents that are all over our apartment. They vent straight outside (I can see daylight through them) so we don't get asphyxiated I guess! It also lets in all the cold/heat and humidity and outside street noise.
(FYI those vents are as clean as we could get them after a good scrubbing)
Kitchen vent Living area vent