High winds, sleet and plain old corrosion can cause a rain cap to break apart, rattle and leak water into your home. If you feel comfortable climbing up on your roof, you can replace the old one yourself for about $40. That’ll save about $150 in labor from an HVAC service company.
You can buy a new rain cap and a sheet metal crimping tool at any home center. Flues are usually 5 or 6 in. in diameter, so buy both size caps and return the unused one. You’ll also need three hex-head or Phillips self-drilling 1-in. sheet metal screws and a drill and bit.
Remove the old rain cap and toss it. Select the correct cap and check the fit (Photo 1). Then secure the new cap (Photo 2).