How to Fix a Rusted Galvanized Flue

If you have a galvanized metal fireplace flue with corrosion or rust, rather than replacing the entire flue, you can repair it. Galvanized metal flues receive stress from heat as well as weather elements creeping down the chimney. Over time, these forces cause the galvanized metal flue to rust. Fortunately, you can repair your galvanized metal flue yourself in as little as one afternoon.

Things You'll Need

  • Vinegar

  • Steel wool

  • Wire brush

  • Rubber gloves

  • Phosphoric acid

  • Bucket

  • Sponge

  • Tack cloths

  • Heat-resistant paint

  • Paintbrush

Step 1

Clean the galvanized metal flue with vinegar and a steel wool pad. Try to dislodge as much rust as possible. Use a wire brush to get off any stubborn rust pieces.

Step 2

Rinse thoroughly with water to get all the vinegar off the surface of the flue.

Step 3

Put on rubber gloves and combine 1 part phosphoric acid with 9 parts water in a bucket. Sponge on the phosphoric acid/water mixture to the surface of the flue. Let soak for about 10 to 15 minutes then rinse. Repeat as necessary until you've removed all the rust from the flue.

Step 4

Apply a thick coat of heat-resistant paint to the galvanized metal flue with a paintbrush. Let the paint dry for at least 24 hours or as long as directed by the manufacturer before using your fireplace.

References & Resources