Guy who trained me in 2019 said never brush a hot flue, and I broke that rule twice this winter
When I got into this trade, the old timer who showed me the ropes in Cincinnati drilled one thing into my head over and over: never run a brush up a flue until it has cooled down, no matter how backed up your schedule is. He had 30 years in and I figured he knew what he was talking about, so I stuck to it for years even when it meant telling customers I had to come back the next day. Then this winter I had a rental property with four fireplaces and the owner breathing down my neck to get it done in one visit, so I brushed two of them while they were still warm. Nothing bad happened. No cracked tile, no damage I could see. Now I'm second guessing a rule I followed for five years. Part of me says he was right and I just got lucky, and the other part says flue tile is tougher than the old guys give it credit for. Any of you brush warm flues on the regular, or do you all wait it out like I used to?