Air conditioners aren’t necessarily restricted to just cooling the air. The cooling is actually a side effect of what the first air conditioners were meant to do: regulate humidity. This is in part why it’s an air conditioner, not an ‘air cooler’ or ‘air freezer’. We’re doing more than one thing to the air.
Water In The Air
Humidity is essentially just gaseous water in the air. It weighs nothing, so it literally just floats around. This is good and bad. On the one hand, water in the air creates our weather. On the other, it makes the air feel hot and sticky, we just struggle to cool ourselves down. This poses an even bigger problem in industrial settings.
Water in the air is readily absorbed by things like paper in printing presses. At one point in time, this could cause tens of thousands of dollars in lost productivity. Old color printings were done one color at a time. The paper was run through the equipment, printed with blue ink. Then yellow could be printed over that to create shades of green, and so on. Paper that absorbs water however, changes its size slightly. Over the course of a mile long roll, the small changes in length were enough to ruin prints. This is where we got the first air conditioner: a really big dehumidifier.
Water condenses on a cool surface. By passing air over a freezing, or near-freezing object, the gaseous water becomes liquid water. Varying air conditioner designs allow us to have different amounts of dehumidification, but the end result remains about the same: drier air, cooler air, and working printing presses.
Managing the Water
Once the water condenses, it needs to be taken care of. There are literally gallons of water in the air, so we can’t just let it drip off the evaporator cool onto the floor or interior casing. For a larger facility, this could be dozens to even hundreds of gallons. Even a small home office can produce a good five gallons of liquid water from dehumidification in just a few hours.
To handle this mess, we have Drip Pans. Pan designs vary by air conditioner, but they are pretty much exactly what they sound like. They’re huge, metal pans that sit under a coil. These are usually several inches deep to avoid any risk of overflowing and have a drain connection on them. Ideally, the drain water is routed into a grey water system, garden, or the local rain water run off collector.
Other configurations don’t always work on that same principle. Window mounted air conditioners have little drip pans, but in large part, they just hope that the water evaporates outside or drips down somewhere harmless, though this isn’t always the case.
If you have a window unit, it’s pretty common to see water dripping off of it. Anything else however? You have a problem. Leaking condensers generally have one of a few things gone wrong:
- Blocked drain
- Rusted drain pan
- Something else leaking onto it
The drain can become blocked by any number of things. Sometimes it’s mold, chipped paint, dirt that’s built up and been washed down by the condensation, or even rust when a unit starts to really age. Your hvac professional can pretty quickly and easily clean out the drain. This might involve a plumbing snake or other specialized tools, but it’s not a system-ending repair.
A failed drainpain however, has the potential to be more expensive. This varies by the design and scale of your condenser, but may involve removing a cool, case, and frame components. Due to the constant exposure to water, it’s not uncommon for a drain pain to eventually fail from rust or corrosion after many years of hard service. Still, this is not an ‘end of unit’ complication, even if a drain pan has failed, your existing system may have many years of useful life left to run.
Drainpans are one of those components that make it essential to regularly inspect your air conditioner. Your HVAC professional should check on your system perhaps three times a year: Spring before first start up, middle of the summer, and Fall after final shutdown. Water damage from drain pan and other issues can be particularly damaging to your building and needs to be caught as early as possible.