Housing agent in the UK

Yesterday afternoon:

Me: "Where is the gas central heating?"

Agent: "Over there, behind the chimney"

Me: "I see. Beyond that wall is another apartment: where do the fumes go?"

Agent: "Up the chimney"

Me: "Good. And where does it get oxygen from?"

Agent: "It does not need any oxygen, it only needs gas"

Me: "The gas central heater does not have any oxygen or air??"

Agent: "No, it only needs gas"

Me: "I think the laws of physics would have problems with that"

Agent: "You'd have to ask that to British Gas"