What's The Deal With Your HVAC System Leaking Water?

2 June 2016
 Categories: , Articles


It's no fun coming home to a soaked patch of carpet or visible puddles on your floor, but it might not be your home's plumbing that's the culprit. Believe it or not, your HVAC system could be springing a leak. HVAC water leaks aren't uncommon, and they can be a bit of a pain to deal with. But before you pick up the phone and call your HVAC technician, take a look at how you can put a stop to those leaks on your own.

It's All About Condensation

Condensation is a natural occurrence during the air conditioning process. As the evaporator coil on your A/C system absorbs latent heat from the surrounding air, it also lowers the relative humidity of the air, reducing its ability to hold large amounts of water vapor. That water vapor condenses into liquid droplets that eventually end up in the condensate drip tray. The water that winds up in the drip tray is eventually drained elsewhere, usually outdoors or through a floor drain located near the unit. But issues with this system may cause leaks. 

Common Causes for HVAC Water Leaks

There are plenty of reasons why your A/C system may suddenly spring a water leak:

  • Clogged drain line - A clogged drain line can cause water to back up in the condensate drip tray, eventually causing the water to cascade over the tray edge.
  • Cracked or rusted drip tray - Damage to the drip tray itself can also lead to water leaks.
  • Cracks, loose joints and fittings and other damage - A cracked drain line or a line with loose pipe fittings can allow water to seep through.
  • Absent P-trap - P-traps are usually added to the condensate drain line to prevent air from entering the line and blocking water flow. It's not unusual for HVAC contractors to forget this crucial step, which could set the stage for a future water leak.
  • Frost/ice formation - Excessive frost buildup on the evaporator coil can create excess water when melted, resulting in the drip tray and drain being overwhelmed by the excess.

Taking Care of Water Leaks

Before you do anything else, you'll want to clean up the mess made by your leaking A/C system. A wet/dry shop vacuum or a good quality mop can quickly take care of any major puddles. If there's any water in hard-to-reach crevices, you can use an absorbent cloth or sponge to coax the water out.

If the cause of your A/C system's water leak stems from a clog in the drain line, you can put your shop vacuum's suction to good use by placing the nozzle over the drain inlet. The force of the vacuum should pull most clogs out. For more stubborn clogs, you may need to use a small plumber's snake to break up the clog before removal.

If your water leak stems from the condensate drip tray, you'll want to inspect it up close for any stress cracks or chips that could let water seep through. For trays made from steel, you'll want to check for signs of rust or corrosion. It's a good idea to completely replace the tray if there are any signs of damage, but minor damage can be temporarily fixed using a two-part epoxy or water sealant.

For damaged drain pipes, you'll want to look closely for any cracks, chips and loose joints or fittings. Depending on the severity of the damage, you may be able to repair the damage with high-quality PVC glue. Also make sure the P-trap is present on the drain line. If not, you may want to have your HVAC technician install one for you.

For water leaks caused by excessive frost buildup, dealing with the underlying cause of the frost buildup (such as a dirty evaporator coil, low refrigerant charge or a clogged air filter) usually takes care of the water leak. In the meantime, it's important to keep an eye on water levels within the drip tray and remove any excess water as the coil is thawed out.

You could try these out, or call HVAC contractors or a plumber for more information and assistance. 


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