1. Must air conditioner condensate be discharged indirectly?
According to the ‘Code for Design of Building Water Supply and Drainage’ (GB 50015-2003):
Article 4.3.13: The drainage pipes of the following structures and equipment shall not be directly connected to the sewage and wastewater pipeline system and should adopt indirect drainage methods:
1. Drain pipes and overflow pipes of drinking water storage tanks (pools);
2. Drainage from water boilers and water heaters;
3. Drainage from medical sterilization and disinfection equipment;
4. Drainage of condensate from evaporative coolers and air conditioning equipment;
5. Floor drainage of refrigerated storage rooms for storing food or beverages, and drainage from defrosting pans of cold air units.
(Note: Condensate from air conditioning equipment should not be directly discharged into the sewage system.)
The commentary on Article 4.3.13 states: “So-called indirect drainage refers to the situation where the discharge pipe of sanitary equipment or a container is not directly connected to the drainage pipeline. In this way, the sanitary fixture or container not only has a water trap to prevent gas from coming back, but also includes an air gap. Although the condensate from air conditioning units is discharged into the rainwater system, the rainwater system can also contain harmful gases and odors. If the drainage pipe is directly connected to the rainwater inspection chamber, there are quite a few engineering cases where odors have entered bedrooms, polluting indoor air.”
(Note: Directly discharging into a regular rainwater pipe may cause odors.)
Article 4.3.14: ‘Indirect drainage from equipment should preferably be directed to nearby sinks or floor drains. If this is not possible, open drainage channels, drainage funnels, or containers may be installed.’
(Note: Indirect drainage to floor drains is feasible.)
Article 4.3.15: ‘Funnels or containers for indirect drainage must not cause splashing or overflow, and should be placed in locations that are easy to inspect and clean.’
(Note: Indirect drainage to floor drains is acceptable if technical measures are in place to prevent related problems.)
Article 4.9.1: “The roof rainwater drainage system should quickly and promptly drain roof rainwater to outdoor rainwater pipes or the ground.”
(Note: Directly discharging into a general rainwater pipe may cause odors.)
Article 4.9.12: “The balcony drainage system should be installed separately. The bottom of the balcony rainwater downpipe should drain indirectly.”
(Note: Directly discharging into the balcony drain pipe does not cause odors.)
The explanatory note for Article 4.9.12 is:
“To prevent rainwater from overflowing from the balcony, the balcony drainage pipe system should be set up separately. At the same time, to prevent unpleasant odors from the balcony floor drain, the balcony rainwater drainage system should drain indirectly into the courtyard drainage pipes.”
(Note: If the drainage pipe drains directly into the balcony, odors are unlikely to occur)
2. Reserved positions for air conditioner condensate pipes? Pipe diameter? Tee height?
For general household air conditioners, there are wall-mounted and floor-standing units (referring to the indoor units), while the outdoor unit is usually placed on an air conditioner bracket. If the condensate water is not drained directly through the floor drain, for wall-mounted units, reserve the tee 700–800mm below the floor slab of the upper level; for floor-standing units, reserve the tee 150–250mm above the floor level.
For high-rise and multi-story buildings, air conditioning condensate pipes must all be equipped with slanted tees, with 2 tees installed for 2 air conditioning units. The elevation of the tees is uniformly set at 250mm below the opening. The pipe diameters are standardized as follows: balcony risers De75, air conditioning condensate risers De50, and balcony air conditioning floor drains all Φ50.
Regarding the installation of air conditioning floor drains, outdoor air conditioning units generally have flanges, which can accumulate rainwater, so floor drains must be installed. However, if the air conditioning position is under a bay window, it is best not to install a floor drain in this case, but coordination with the building design is necessary to avoid having a flange.
The air conditioner’s condensate riser is installed next to the air conditioning panel, with a DN50 drainage riser and a reserved DN25 pipe interface for connecting the air conditioning unit’s condensate water. The distance from the pipe to the panel surface is 100mm. If the air conditioner is installed on the balcony, it is best to set up a separate drainage riser.
Post time: Dec-16-2025