There Is Rust In My HVAC System, Is That Bad?

We have all grown up with the impression that rust is bad and a sign of something failing or falling apart. Is that true for an HVAC system?  Baggett Heating and Cooling is here to talk about rust and what you need to know about it in terms of your system.


In Clarksville, TN there are two common applications of systems on residential homes. Packaged and split systems.  Packaged systems contain all the components in one “package” and sit entirely outside. Split systems are split into indoor and outdoor sections.

Any outdoor equipment has been designed for those conditions and during its normal life span, you aren’t likely to see rust on the exterior of the system.

However, inside the different applications of systems components can and will rust. The most common components that we may condemn or fail due to rust (or hole caused by the rust) are coils and heat exchangers. Excessive moisture and high temperatures are the most common causes of rust. But it may surprise you (it did me!) that engineers of systems actually plan for and put certain materials together so they may rust in a certain order and that rust or “galvanic corrosion” is actually protecting another metal close by.

If you are a bit technical (and nerdy like me) and want to learn more, click here.  

So, rust may not always be catastrophic. But rust is certainly an indicator of longevity and in many cases can be indicating a problem that can be repaired or resolved. 

It’s important to point out, that while rust on an indoor coil may not mean the coil is leaking refrigerant, it can most definitely mean the system is more prone to clogged condensation drains. Rust and debris from a dirty coil will absolutely flow out with the moisture the system removes and clogs a drain. Therefore if a technician informs you of corrosion on your coil but it is not leaking refrigerant, it may mean you want to keep an eye on the drains more closely. It is always wise to have routine maintenance completed (which includes drain cleaning) but it may also be wise to increase the frequency of cleanings if your coil shows signs of galvanic corrosion.

Baggett Heating & Cooling has served the Clarksville/Montgomery County area for over 40 years. Contact us by phone, text, or email.