By Matthew Baring-Gould, Kingscliff-based drainage plumber. Servicing Tweed Heads for 4 years. 5.0 stars across 173 Google reviews. Licensed NSW 383340C and QLD 15036450. ABN 74 605 392 348.
Commercial aircon drainage install at Chinderah. Ran a new condensate line from the courtyard aircon across to the existing downpipe on the right side of the doorway, parallel to the building, under lifted Astroturf. Added a tee overflow on the aircon line just before the downpipe connection so any future stormwater block in the downpipe would back out of the tee instead of into the aircon. Separately, ran a 50mm PVC Tundish line behind the aircon units next to the main driveway, picking up each aircon with square junctions, and core-drilled the kerb to discharge direct to the street.
What the customer called us for
Commercial client called us out to extend the aircon condensate drainage. Existing aircon units were discharging in places that risked flooding the slab or backing up through the aircon itself. Wanted proper stormwater routing for the whole aircon layer.
What we found when we got there
Standard commercial drainage problem on a multi-unit site. Each aircon has condensate it needs to get rid of. Builders often tee the condensate drain into the nearest stormwater without thinking about what happens when the stormwater blocks. If the stormwater backs up, the condensate line is the lowest point and water ends up running back through the drain pan of the aircon itself. Expensive aircon damage from a cheap drainage shortcut.
Why we did it this way
The fix is two design decisions. (1) Put a tee overflow on the condensate line just before it connects to the stormwater, so if the stormwater does block, water escapes out of the tee instead of up into the aircon. (2) For aircon banks near a kerb, run a dedicated condensate line direct to the kerb instead of into the stormwater. That gives the condensate its own path, isolated from any stormwater issues. We do this on every commercial aircon drainage job because it is cheap now and saves a four-figure aircon repair later.
What we did on site
- Lifted the Astroturf in the courtyard to run the new condensate line parallel to the building.
- Joined onto the existing line and extended it across to the downpipe on the right side of the doorway.
- Installed a tee overflow on the condensate line just before the downpipe connection point as a back-out path.
- Connected the extended condensate line into the existing downpipe.
- For the second bank of aircon units near the main driveway, ran a dedicated 50mm PVC Tundish line behind the units.
- Picked up each aircon with square junctions so each one has a clean inlet into the common Tundish line.
- Ran the Tundish line to the kerb and core-drilled the kerb to fit the 50mm discharge pipe.
- Cleaned up site and removed all rubbish.
The result
Aircon condensate from both banks of units now has a proper drainage path. Tee overflow on the courtyard line means a future stormwater block cannot damage the aircon. Dedicated Tundish line direct to the kerb for the driveway aircons isolates them from the main stormwater entirely.
If you have the same issue
If you own or manage a commercial property with multiple aircon units, check where the condensate actually drains. If it is teed into the stormwater without an overflow, book a plumber to either add overflows or run dedicated condensate lines. Saves aircon units, protects the slab, and costs a fraction of what it will cost to fix after a stormwater block. Call Matty on 0447 188 394 or request a quote.
Customer names and addresses have been withheld. Individual results vary. Drain Masters Plumbing is licensed in NSW (383340C) and QLD (15036450).
Frequently asked
What is a Tundish?
A Tundish is an open-top collection fitting that receives water from one or more drainage lines and discharges it through a single outlet. In this install, the Tundish is behind the aircon bank and collects condensate from each aircon unit through its own junction. The whole bank discharges through one 50mm line to the kerb.
Why core-drill the kerb instead of running to the gutter?
Core-drilling the kerb gives you a dedicated, permitted discharge point direct to the roadway drainage. Running to the gutter means the condensate crosses the footpath and the driveway, which stains the concrete and creates a slip hazard. The core-drill is a once-only job and the fitting sits flush in the kerb.
Can I just run the aircon condensate into the stormwater and skip the overflow?
You can, and plenty of builders do. The problem is that if your stormwater ever blocks, the condensate has nowhere to go but back up into the aircon. The overflow tee is a ten-dollar fitting that saves a thousand-dollar aircon repair. Worth it on every install.
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