Yes, it is safe to use vinegar to clean a brick fireplace. A vinegar and water solution alone is not strong enough to cut through the soot, but vinegar is an excellent deodorizer to help remove ...
"Use a stiff-bristled brush to gently remove loose set from the bricks. Begin at the top of the fireplace ... notice soot buildup or dark discoloration on the bricks, it’s time to clean.