Air Conditioning Condensate Disposal

Condensate Description
The process of removing heat from the air is often called air conditioning. Water is a byproduct of air conditioning because water vapor condenses out from the air when the air temperature is reduced. In areas with high humidity, air conditioning can produce signifi cant amounts of water. The water removed from the air during air conditioning is called condensate.

Condensate Disposal Location Requirements
1. Do not discharge condensate on to a street, alley, or any other place that would create a nuisance. Some jurisdictions, particularly in warm moist areas, require that you discharge condensate away from the foundation. Verify discharge location requirements with the local building official.

Condensate Discharge Pipe Requirements
1. Use at least (≥) ¾ inch internal diameter pipe for primary and auxiliary condensate discharge pipes. Do not decrease pipe size between the collection and discharge point.
2. Install horizontal pipe sections with a uniform slope in the direction of the discharge point of at least (≥) 1/8 inch in 12 inches                                                                                          3. Use fittings, primers, cements, hangers, and other components that are compatible with the pipe material. Install the pipe according to the provisions in Chapter 30.
4. Use pipe material and use a pipe size that will accommodate the condensate temperature, pressure, and flow rate produced by the air conditioning system. Use an approved method to select pipe size when connecting together multiple condensate discharge pipes.
5. You may use most water supply and drain pipes for condensate discharge pipes. The most common condensate discharge pipes are PVC, CPVC, and ABS.

Condensate Auxiliary (Backup) System Requirements
1. Install an auxiliary condensate system when the air conditioner evaporator coil is located where building damage may occur if the primary condensate discharge system malfunctions. This usually applies to evaporator coils installed in or above finished space. Many jurisdictions require auxiliary condensate systems for all air conditioning systems, unless all of the appliances are located outside the building.
2. Install one of the following auxiliary condensate systems when an auxiliary condensate system is required.

Condensate Auxiliary Drain Pan with Discharge Pipe
1. Install an auxiliary drain pan under the evaporator coil. Use a pan that is at least (≥) 1 ½ inches deep and at least (≥) 3 inches larger than the evaporator coil in both length and width. Construct the pan using either at least (≥) 0.0276 inch galvanized sheet metal or at least a (≥) 0.0625 inch nonmetallic pan.
2. Slope the pan toward the discharge pipe connection.
3. Install the auxiliary discharge pipe using the same materials and methods as the primary discharge pipe.
4. Terminate the auxiliary discharge pipe at a conspicuous point so that the occupants can see that the primary condensate discharge system is not functioning properly. A conspicuous point often means above a window.

Condensate Auxiliary Drain Pan with Water Level Cutoff Switch
1. Install an auxiliary drain pan under the evaporator coil. Use a pan that is at least 1 ½ inches deep and at least 3 inches larger than the evaporator coil in both length and width. Construct the pan using either at least (≥) 0.0276-inch galvanized sheet metal or at least (≥) a 0.0625 inch nonmetallic pan.
2. Install a water level cutoff switch in the pan that will shut off the air conditioner before the pan overflows.

Condensate Auxiliary Discharge Pipe Attached to Evaporator Coil
1. Install an auxiliary condensate discharge pipe at the evaporator coil interior condensate pan. Connect the auxiliary condensate discharge pipe above the primary condensate discharge pipe.
2. Use the same type and size pipe for the auxiliary discharge pipe as required for the primary discharge pipe. Slope the auxiliary discharge pipe toward the discharge point with a slope of at least (≥) 1/8 inch in 12 inches.
3. Terminate the auxiliary pipe at a conspicuous point so that the occupants can see that the primary condensate discharge system is not functioning properly. A conspicuous point often means above a window.

Water Level Cutoff Switch
1. Install a water level cutoff switch above where the primary condensate discharge pipe connects to the evaporator coil and below the evaporator coil interior condensate pan overfl ow rim, or you may install the switch in the primary or secondary discharge pipes. The switch location should allow the switch to shut off the air conditioner before water overfl ows into the building. See illustration on next page.

Water Level Cutoff Switch for Downflow Air Conditioners
1. Install a water level cutoff switch on air conditioners where the supply air is directed downwards. This also applies to any air conditioner where it is not possible to install an auxiliary drain pan under the evaporator coil. Install the switch below the evaporator coil interior condensate pan overflow rim.
2. You may not substitute water level cutoff switches located on the exterior of the evaporator coil or located in the condensate drain lines for the interior cutoff switch.

Auxiliary Drain Pan Separation from Appliances
1. Install all parts of appliances and insulation that could be damaged by water in the auxiliary drain pan above the flood level of the pan.
2. Use supports located in the drain pan that are water resistant and approved for the intended use. Example: do not use wood blocks in the drain pan to support an appliance.

Condensate Auxiliary (Backup) System Requirements for Category IV Appliances
1. Install an auxiliary condensate drain pan under most Category IV condensing appliances. The pan is required when the appliance is located where building damage may occur if the primary condensate discharge system becomes blocked or does not function. This usually applies to appliances installed in or above finished space. A common example of a Category IV appliance is a high efficiency gas furnace.
2. Install the pan and the disposal pipe using one of the previously discussed methods.
3. You do not need to install a drain pan if the fuel-fi red appliance automatically shuts down when the primary condensate discharge system malfunctions.

Condensate Disposal Best Practice
In areas with warm and humid summer conditions, the cold condensate can cause moisture to condense on the outside of the primary condensate disposal pipe. This condensation can, over time, damage wood and drywall and provide moisture for fungal growth. Insulate the primary condensate disposal pipes in areas with warm and humid summers.