If this is “strata” why are you paying the gas bill?
In strata situations there is sometimes a central gas-fired hot water system. The individual units have a water volume meter on their hot water supply and then pay a ‘gas bill’ that is worked out from the volume of delivered hot water as their pro-rata share of the gas bill for the central water heater.
That said, this does look more like the size of gas hot water storage heater the might be just for the one unit.