Don't trip the water heater overflow (pressure & temperature relief valve) too often, twice a year is enough. If you need water to fill the trap, bring it downstairs in a pitcher or watering can.
Heating and air conditioning units should suck air for climate control via a return air vent coming down from the house, not relying on basement air unless there are heat or cool air registers with more square inches in the basement. HVAC equipment partitioned off and needing intake air must have louvers to the outside or louvers to the rest of the basement. Combustion air should come from a louver or intake pipe to the outside.
Heating and air conditioning units should suck air for climate control via a return air vent coming down from the house, not relying on basement air unless there are heat or cool air registers with more square inches in the basement. HVAC equipment partitioned off and needing intake air must have louvers to the outside or louvers to the rest of the basement. Combustion air should come from a louver or intake pipe to the outside.