Understanding Drains & Your Home’s HVAC System

Plumbing systems in a home are a major modern innovation. They keep our neighborhoods clean, help us dispose of waste, keep our home’s interior dry, and even supply hot and cold water on demand. Keeping a home’s plumbing system properly maintained can go a long way toward averting leaks and destructive spills. Understanding how your home’s HVAC system may tap into your plumbing system can also help you identify which professional to call, the plumber or the HVAC technician, if you have a leak.

Drain lines in your home

Bathroom drain

In newer homes, 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.

Drain maintenance

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 condensate drain

Outdoor condensate drain on an older home.

Older homes may have condensate drains that drain to the outside.

If you have water pouring from your ceiling, the leak could be from a clog in your plumbing system or it could be your HVAC condensate drain overflowing because it is stopped up. One way to tell is to locate your condensate drain, which will usually be sitting above an open drain pan in your attic. It will be pretty easy to tell from looking at the pan and the drain if that is the source of the problem.

We recommend “ceiling saver” switches that turn off the air conditioner if the drain pan becomes dangerously close to overflowing. By cutting the power, the HVAC system will stop working. This will give you time to call an HVAC technician to come out and diagnose the problem. If you already know what the problem is, it can make it that much faster to solve. During the hotter months, which is most of the year in our area, condensate drains can easily become clogged because of the growth of algae and slime because they are located in a humid environment where the air conditioner is actively removing water from the air. Installation of an ultraviolet lamp in your evaporator coil can slow this process down quite a bit, and the ceiling saver switch is also a bit of extra insurance. We can also install an algicide pad in your drain which can last up to six months and which continuously releases an ammonia-based quat, a sanitizing compound that help prevent the build up of slime in your system.

Give us a call

If your condensate drain is draining water down your ceiling, give the Rob and Kenny at Terry’s A/C and Heating a call at 281-495-7830 for quick help! We can help you locate your condensate drain so you can do the maintenance yourself and install switches so surprise water leaks caused by your air conditioner will be a thing of the past.  If it turns out you do need a plumber, we have several we can recommend who we use for our own homes and customers. Find out what our customers say about us, and what makes us different from other HVAC technicians in the West Houston, Fulshear, Katy, Richmond, Meyerland, and Rosenberg area.