crumbling sealant at flue to chimney penetration

Old 06-30-16, 11:32 AM
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crumbling sealant at flue to chimney penetration


between my boiler flue and chimney is crumbling. Should I remove the existing loose sealant and replace it with flue cement or totally remove the sealant and replace with flue cement? I've attached a link to a photo below.
Old 06-30-16, 11:35 AM
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Welcome to the forums.

Concrete wall? If so, I'd be thinking about digging it out and replacing with hydraulic cement.

Hang tight, though, as this is not my area of expertise and someone with that savvy should be by shortly.
Old 07-04-16, 12:48 PM
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I would replace it all. You can use either furnace cement or ordinary mortar mix.

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