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6 Tips For Successfully Coating HVAC Systems/Ductwork

  

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Coating HVAC systems and ductwork can be a challenge sometimes.  In talking with contractors and helping them solve their coating challenges I’ve found that many times it’s the little things that cause problems.  Here are 6 tips to help minimize problems and insure a successful coating project.

1. Make sure the surface you are coating has been cleaned first.  This may sound obvious but unfortunately some contractors cut corners and don’t clean the surface first.  You can coat a dirty surface and it may hold up for a while but eventually the coated dirt will separate from the duct and that coating project will fail and need to be redone.  Every coating manufacturer stresses the need for a clean surface prior to coating.  Many recommend a primer in cases where the surface can’t be cleaned as well as it should be.  The primer bonds with the imperfect surface and the coating then bonds with the primer for a long lasting coating project. 
2. Make sure your airless sprayer is the right size for the coating you are applying.  There are many coatings on the market with a wide range of viscosity and fiber content.  An airless sprayer and a cart spray/robotic system that work well with an average viscosity coating may not work well with a coating that has a thicker viscosity.  Average viscosity coatings need an airless sprayer that has 1.4 hp motor and a .7 gpm pump while a thicker viscosity coating will nee an airless spray that has 2.0 hp motor and a .95 gpm pump.  An undersized airless sprayer is one of the most common problems on coating projects. 
3. Thoroughly mix and strain your coating before applying. This step should eliminate or at least drastically reduce the chance of your spray tips getting clogged on the project.   There is nothing worse than having to stop a coating project to clean out spray tips and screens.  It really reduces your productivity and profits. 
4. Coat a trial section first.  We highly recommend doing a trial section of ductwork first because it gives you a chance to:
   • Determine if your airless sprayer works well with your cart spray system and coating.
   • Determine what retrieval/spraying rate gives you’re the level of coating you want on the project.
   • Determine with the building owner/representative on what is an adequate coating thickness before you coat the whole project.  You don’t want disagreements after you are all done coating.  
5. Inspect your work.  Inspect your work as soon as can to see if anything was accidentally missed or needs a little more coating.  Insulated surfaces on a project may not necessarily be in the same condition throughout the HVAC system so some areas may need more or less coating.   
6. Clean the spraying equipment.  The final step in any spraying project is cleaning the airless spray equipment and any cart/robotic spray system used.   You typically run warm soapy water through all the spraying components until clean. And then you take the spray tips apart to make sure the tips and any  screens are clean.  Once the coating dries it is very difficult and time consumming to clean the spraying equipment.  Plus, you want to be ready to go for the next project.

It’s the little things that you do or don’t do that will determine your success when applying coatings in HVAC systems/ductwork.  Many times, the up front preparation and cleanup afterwards will take more time than the actual spraying.   Please feel free to call me at 800-597-3955 or 952-808-1619 if you have any questions about coatings, airless sprayers and cart/robotic spray systems. 

If you want more information on coating HVAC systems we recommend our Introduction to Coating HVAC Systems Guidelines.   It includes a chart on popular coatings and their characteristics along with a chart on coating and airless sprayer compatibility.