TIL you can spot a bad flue tile by tapping it with a screwdriver handle, not a metal tool
Was on a job in Boise last week, a 1920s house with a fireplace the owner swears they never use. I tapped each flue tile with the plastic end of my screwdriver and one of them gave off this dull thud instead of the sharp ring, turns out it had a hairline crack about 5 inches long. If I had used my metal scraper like I used to, I probably would have smashed right through it and made a small problem into a $2,000 liner job. My old boss taught me the metal tool trick 12 years ago and I never questioned it, but a cracked tile sounds completely different from a solid one when you tap it soft. Anyone else use the handle tap method or do you have a better way to check tiles without a camera?
Back in 2019 I was doing a chimney sweep in Nampa and the homeowner had a stack of old brick from a 1940s rebuild sitting in the yard, so I practiced tapping both kinds of tile side by side for an hour. The dull thud on a cracked one is so obvious once you hear the difference, it sounds dead compared to the ring on a good one. I'd been using the metal end of my brush rod for years before that and cringed thinking about how close I came to breaking tiles on old flues. One thing I'd add is tap in a few spots, not just the middle, because a crack near the joint won't show up where you'd expect. Also go easy around the smoke shelf, those bottom tiles take a beating and crumble if you get rough. Handle tap plus a flashlight down the flue gets me through most jobs without dragging out the camera.