You may not want to hear form me again, but I say, I can't tell from the photo, it hasn't plugged up, that's for sure. If the black is shinny and hard, is likely creosote and it may need to be "power cleaned", and if you have an airtight installed with a stainless steel chimney liner, they'll likely clean the chimney first, then seal that part off. That should be included in any installation estimate, but ask before signing. A hot fire can ignite creosote, and cause a chimney fire, have it inspected by a licensed chimney service before using is my recommendation.

Hello Forum, I've got a 2-flue chimney, with fireplaces in my basement, and directly above that on the 1st floor. 1st floor is in use as a wood-burning fireplace. The basement fireplace has been closed up, and the flue has been used for the past 40 years as exhaust for the boiler. I'm replacing the boiler with a direct vent unit which will be vented directly to the side of the house. I will no longer need that flue for the boiler. We can close up the hole in the side of the chimney. Can I re-open the basement fireplace that used to be served by that flue, and use it? I don't mean do the work myself; I'd have a professional do it. My question is more based on code (I'm in NY state) and the safety of such an arrangement - are dual-flue chimneys up to code in the modern era, or are they just grandfathered in if they are still working? It would matter because we would be re-opening a fireplace that's already closed, so it would probably require a permit. Thanks in advance, Nelson

I wouldn't make a big deal about it. Probably less than $1000 fix. I heard they have a sponge technique where they put a sponge on a pole full of cement like paste and seal up any cracks or holes. This guy will "sell" you his services. He'll probably tell you its best to do it now before the sale of the estate. Just keep in back of your mind that you can use it as a negotiating point in the sale. Offer the buyer to fix the flu liner (if there's a real problem).

Thanks. I think the gap is a bit too wide for caulk, so I'm considering foil tape. It's 4' away from the water heater and might not be too hot at that point. Not sure if that's too half-baked of a solution.