> Now, gas showers are No. Proper gas powered water heaters have oxygen sensors for quite some time, and ours kick-in before we feel anything about oxygen leve

> Now, gas showers are No. Proper gas powered water heaters have oxygen sensors for quite some time, and ours kick-in before we feel anything about oxygen levels, and it doesn't reset until you get proper amount of fresh air in. Moreover, newer models are completely sealed, breathing air from outside and directly dumping exhaust outside with a fan, via a coaxial pipe.