Many people aren’t aware of the HVAC and plumbing links in their home. After all, what does plumbing have to do with heating and cooling? Generally, you won’t even notice HVAC and plumbing links until something goes wrong. Then, it may be hard to ignore. Here are three examples of places in your home where plumbing and HVAC intersect.

Central AC Condensation

A central air conditioner may produce more than 10 gallons of condensation daily. When everything functions correctly, water collects in a condensate drip pan beneath the air handler, then drains through a line connected to the house’s plumbing. If something goes wrong — often a clog in the drain line caused by algae growth — the drip pan overflows every time the AC cycles on. Expensive indoor water damage may occur before you become aware of the problem.

With annual preventive AC maintenance by a qualified service technician, HVAC and plumbing links, including the condensate drip pan and the drain line, are inspected. If algae growth is present, the pan will be disinfected and the drain line will get blown out. Biocide tablets placed in the drip pan will inhibit algae growth for the remainder of the season.

High-Efficiency Furnaces

Gas furnaces with AFUE (Annual Fuel Utilization Efficiency) ratings above 90 incorporate a secondary heat exchanger to extract heat from water vapors in furnace exhaust gases. This acidic water runs through a drain line into the plumbing drain system or to an outdoor discharge point. If a blockage occurs, water backing up into the furnace triggers a safety switch that automatically shuts down the unit. Until a service technician clears the blockage and resets the furnace, you’ll be without heat.


Whole-house dehumidifiers connected to HVAC ductwork in the attic is another example of HVAC and plumbing links. A blockage in the unit’s condensate drain line can cause leakage and overflow up in the attic — where you probably won’t know about it until significant water damage has occurred. Annual professional maintenance of HVAC and plumbing links helps ensure reliable dehumidifier drainage.

For more information about HVAC and plumbing links, ask the professionals at Mowery Heating, Cooling and Plumbing.