In newer homes, HVAC condensate drains are tied most often to bathroom drains.
Common drain lines inside your home include in your bathrooms (sinks, shower or tub, toilet), kitchen (sink, water line to your freezer), laundry room, and water heater. In new homes, city codes require drain lines from the air conditioner’s condensate line which are often located in the attic to tie in or be plumbed to the home’s plumbing system. Typically, those 3/4″ pipes are plumbed into a bathroom sink’s drain that is on average 1-1/4″ or 1-1/2″ in diameter. The thinking is that any water that is collected by the condensate drain can be swiftly and efficiently drained out of the home through progressively larger pipes as it exits your home through the sewer line. The trap in the bathroom sink also prevents the sewer gasses from coming into your home and into your air conditioning system.
In older homes, condensate lines located in the attic where the evaporator coil is busy removing humidity and cooling the air with refrigerant-charged lines are not tied to a home’s plumbing system. They may have a separate exit point from the home. Whether your HVAC system is tied to your plumbing or not, when drains get clogged, they are a messy business.
Maintaining drains and your home’s HVAC system
It pays to be vigilant when it comes to keeping your home drain lines clear of clogs. Plumbers often recommend regular maintenance by adding a biological/enzymatic cleaner that can organically remove sludge, algae, slime, and gunk. Skip harsh chemical-based drain clearing products, like Drano or Liquid Plumr, which can damage fixtures and pipes and is dangerous to people and the environment. If you have a slow drain anywhere in the house, fix it or have it fixed right away. If the drain is in your bathroom sink, you can remove the p-trap (curved pipe underneath the sink) to clean out any clogs pretty easily.
If you have a slow-draining sink or other drain anywhere in the home and your home’s HVAC system is tied into your plumbing system, it can cause problems in the form of water leaking where it shouldn’t be when water backs up through the system. Sinks or other drains that are not used often are at particular risk of causing these problems.
If you are in an older home, a plumbing clog in the house won’t affect the condensate drain, but the condensate drain is still at risk of clogs too if not regularly maintained. It is easy for homeowners to maintain an HVAC condensate drain by pouring vinegar down the drain on a quarterly basis.
Locating your HVAC condensate drain