Can an Air Conditioner Drain Right Into a Garage?

Central Air Conditioners

• In a central air conditioner, the condenser/compressor is placed outside the home for a reason. Air conditioners work by absorbing heat from the indoor air into cold refrigerant, and pumping that refrigerant outside, where it re-pressurizes and its absorbed heat is dumped. The warmer the ambient temperature, the more difficult it is for the absorbed heat to be discharged. Over time, your central air conditioner will heat up the garage and have to work increasingly harder to discharge heat.

Window/Wall Air Conditioners

• Window and wall air conditioners operate on the same basic principals as central units. Accordingly, they also require ventilation to the outside in order to dump waste heat and condensation. Window and wall air conditioners are typically more indiscriminate about where they dump their condensation, and ensuring that the waste water is caught and does not soak your garage floor can be difficult.

Attached Garages

• An additional problem, in homes with attached garages, is that inevitably some amount of the heat dumped into the garage will make its way through the walls back into the house. This means the air conditioner will need to run longer to reduce the indoor air temperature, and your energy usage will increase.

Note on Condensation

• Condensation is created in an air conditioner during the process of cooling the indoor air. This condensation is drained into a condensate pan, and is then pumped through a condensate pump outside your home or into a floor drain. Condensation can safely be drained into the garage, provided it is contained in some sort of water catch or rain barrel. During periods of high humidity, the amount of water put out by an air conditioner can be substantial.