The ways rain affects an HVAC system are mostly indirect. After all, the only outdoor portion of your heating/cooling system is the outside condenser coil and compressor unit of the air conditioner, typically situated just behind or to the side of the house. That component is designed and engineered resist normal rainfall. The remainder of the air conditioner and all of the furnace are indoors. Nevertheless, there are still some ways rain affects an HVAC system. It’s a good idea to be aware of them if water-related issues occur.
Flooded Condenser Unit
While the outside half of the central air conditioner is rain-resistant, it’s not designed to be submerged in water. Localized flooding due to unusually heavy rains can swamp residential areas with standing water. Generally speaking, if flood water exceeds a depth of 15 inches, it may damage internal electrical components including circuit boards and connectors inside the external condenser/compressor unit of the central A/C. Moving flood waters may also undermine the concrete pad on which the outdoor unit is mounted.
Heavy rain can also inundate HVAC ductwork if it floods the crawl space under the house where system ductwork is often routed. Ductwork is typically not waterproof. Water entering the ducts may remain contained inside duct segments long after the flood itself has receded. This water will deteriorate ductwork as well as form an environment for toxic mold growth inside the ducts.
Roof leaks during rainfall can occur unnoticed in the attic for some time. Chronic leakage into the attic can seep into HVAC ductwork installed there. This ongoing moisture will rust and corrode ducts as well as trigger mold growth. Rain leakage into the attic also saturates attic insulation, severely reducing its insulating properties. Insulation compromised by moisture allows increased heat transfer into and out of the attic and causes your furnace and air conditioner to run longer cycles to compensate.
For more info about how rain affects an HVAC system, contact the professionals at Roth Heating & Cooling.