Drain Pans - how to handle


How do you handle rusty drain pans?

How do you handle a rusty, corroded condensate pan? The only sure thing is that if isn’t handled, major problems can follow. Unless it is falling to pieces, in which case the only option is to replace the pan, it can usually be coated or treated to extend its service life.

But what to do? Machado has explored a number of options and products, each of which has its advantages and drawbacks. The advantages include effectiveness and durability, ease of application, low cost. The drawbacks include low effectiveness and durability, difficult, labor intensive application and high cost.

Rusty Drain Pan

It does not do to simply wire brush the pan and then paint it with an off the shelf rust resistant paint or roofing tar. Condensate pans are almost constantly under water, particularly in larger commercial air handling units, and coatings not designed for continuous submersion will peel and flake over time often causing worse conditions than before.

The solutions range from replacing the pan to simply wire brushing the pan and keeping it clean. Replacement is not only very expensive, it is sometimes virtually impossible without major reconstruction.

But when it comes to coating and/or treating the pans there are several products we have tried.


The “king of the hill” in pan coatings is generally considered to be a product called Pancrete, by Controlled Release Technologies, Inc. According to their website, “Pancrete refurbishes corroded HVAC condensate pans. Compliant with NFPA 90A. Its water repellant surface and uniform leveling prevent water buildup in HVAC condensate pans. It prevents further corrosion on HVAC surfaces including condensate pans, interior and exterior side-walls, structural members, fan blower enclosures, inlet and outlet plenums, corroded chilled water piping, and other HVAC system components such as the interior and exterior of ducts.""

The final product is truly impressive and the treatment will last for years, possibly much longer than the design life of the pan. The material is self-leveling and actually creates a thick (up to ¼) new surface that is hard as steel and as you can see, it looks good. It is very expensive, but possibly the least expensive in the long run.

  Before and After Pan Lining

Another product we have used is called “Flex Guard” by Thermoguard. (above pictures) Flex Guard is an epoxy material that is applied to the prepped surface and creates a 1/16”-1/8” thick layer that can adhere to the sides of the pan. The result is actually a whole new “pan” within the existing pan. Again, this is a very impressive product that is very effective, long lasting and it looks good as well.

The high gloss surface makes it easy to clean years after installation.

The application of this product requires several steps and is very labor intensive, but the final product is totally worth it.

  Before and After Pan Lining

A recent product we have experimented with is called “Corlar 2.1-ST” by DuPont. This is, according to the literature, “a satin gloss, high build epoxy mastic…that is a high performance direct-to-metal coating or topcoat on carbon steel, galvanized steel, aluminum, concrete, concrete block and wood…” So it is quite versatile. We found the ease of application and necessary prep time is less than either Pancrete or FlexGuard. The thickness of the coating is adjustable according to what is required. From our initial observations, the Corlar dries to a steel hard surface that appears to be extremely effective. And the cost is considerably lower than either of the other. Will the longevity rival that of Pancrete or FlexGuard? Only time will tell on that one.

Cost comparison for a pan 2’ x 8’ (typical of a commercial built-up unit)

  Drain Pan Chart

The labor costs will vary depending upon how much prep is needed to get the pan in a condition to coat, access to the unit and logistics considerations.

Bottom line? We have applied all three and are satisfied with the results in all cases. Where cost is a consideration, the Corlar will be a viable solution.

But the real bottom line is that when a condensate pan is rusted, leaking and in need of attention, do not wait! The result may be major leaks and the possible need to replace rather than repair the pan.

Machado has a proven track record in addressing corroded condensate pans – call us now and we’ll do it for you!

Tom Pula