We rely on HVAC professionals to clean and tune-up our heating and air conditioning systems. Most homeowners know they have to periodically replace their HVAC filters. Very few owners know they have to flush condensate lines monthly during the summer. This is a surprise to new homeowners in Florida. Learn what a condensate line does. Then you'll know why it's so important to keep it clean.
What Does the Condensate Line Do?
Your HVAC system cools and/or heats the air in your home. When you're cooling your house, the coils in the air handler get cold. This causes the humidity in the air surrounding the coils to condense on the outside.
The condensation (water) has to go somewhere and that's the role of the condensate line. It's also called a condensate drain line or condensate drain because it sends excess moisture outside your house. Make sure you know where your condensate line releases water outside your house … so you can spot problems easily. Read The Main Reason for Condensation in an Air Conditioner if you want to learn more.
Amazingly I spotted this clogged condensate line while today while walking around my neighborhood. The owners are from Pennsylvania so they're not familiar with cleaning out this drain line. Fortunately it's pretty obvious here that there's gunk in the pipe. But clogs can also be hidden where you can't see them.
What Happens When the Condensate Line Gets Clogged?
Truthfully, each time I write a new article I learn something new. It's a level of detail that didn't come up when I wrote anatomy of a central air conditioner.
Today I realized I didn't understand how the water condensing on the coils got into the condensate line. There's a pan under the coils that collects the water and from there, the condensate line carries the water to one of two places. The pipe (typically made from PVC) can go directly to the outside of your house. Alternatively, the condensate line can send the water into one of your home's drainage pipes that's part of your plumbing system.
Often (but not in my Florida house) there is a second drainage pan under the entire air handler unit. If the pan under the coil fills up due to a blocked drain, the second pan will catch the overflow and hopefully drain properly. This is especially critical when the air conditioning system is in the attic. With my handyman business, we had several jobs where the secondary drain pan failed. Repairs here can be extensive from replacing the drip pan and wood supporting it, plus drywall on the ceiling and walls and other water damage.
If your air conditioning unit is in the attic, you'll find lots of useful information about HVAC drain pans here (there photo above) …
How to Avoid a Clogged Condensate Line
There is a safety switch, called a float switch (watch video), that will shut your air conditioner off if the condensate line doesn't drain. When that happens, you might be able to clean the drain … or you might need to place a service call to your HVAC company.
To avoid this emergency, you should flush out your condensate line each month (do it when you change your filters). It's pretty easy but PLEASE don't use bleach like this video recommends because it can eat away critical materials in your system. My HVAC contractor who just completed my bi-annual cleaning and tune-up, recommended a half gallon of hot water plus two cups of white vinegar.
All you need to buy is white (cleaning) vinegar and a funnel. My recommendation is to use a different color funnel (blue shown here, less than $2 on Amazon) that your kitchen ones, and keep it in the HVAC closet.
Trust me, cleaning the condensate line is a lot less work that cleaning up after a water leak. While staying at my best friend's condo, I came home after a weekend away and ran to the toilet. Sitting there I noticed there was water on the floor. You guessed it. The condensate line was plugged up and the drip pan overflowed spilling water all over the floor.
It was late that night so I emptied the drip pan and hoped it wouldn't fill up overnight. The next morning I headed off to Home Depot and purchased the following:
- DampRid to help absorb moisture … helpful but not a total solution.
- 1/4 HP Air Mover Blower Fan … for water damage restoration (roughly $100).
Why did I spend this money? I could easily see that the water had already climbed up the HVAC closet door, the door jambs, the drywall plus the baseboard. If I didn't dry everything out quickly, it would all have to be removed and replaced.
Funny looking back now, I was able to dry this small area out and minimal repairs were needed. But I wasn't nearly as lucky with my own house that flooded last year. We did have to replace all the doors, door jambs, drywall and baseboard … a nightmare you don't want to go through!
PS Want to learn more about your HVAC or air conditioning system?
- Anatomy of a Central Air Conditioner (or HVAC system).
- HVAC Installation & Attention to Detail
- Ductwork Delivers Heat & Cool Air
- How Many Types of Air Conditioners Are There?