Expert: James Ball - 2/18/2011

Question
QUESTION: We have had our chimney torn down and rebuilt.  Each brick was "cleaned" of its mortar. Also the clay tiled chimney liner was inspected and the damaged tiles were replaced.  When the tiles were set in place they were mortared in place but the excess mortar was not removed from inside the flu.  Now when I look up the chimney, I can see the mortar hanging from between each of the tiles where they meet.  Should this extending mortar be removed to make a smooth surfaced flu?  If it should be removed, how can this be done without damaging the clay tiles? We now have a secondary combustion fireplace insert venting into this chimney.

ANSWER: Hello William, yes that should be remove it some sweeps have an chisel that connects to their rods to push up or down to remove it. what is this  "secondary combustion fireplace insert venting into this chimney." do you have 2 fireplaces into one flue or os there separate flues for each?
if not your chimney might not be safe to use.
James


---------- FOLLOW-UP ----------

QUESTION: I have one fireplace with its own chimney flu.  The fireplace insert is installed into our brick fireplace. If I just leave the excess mortar, will it deteriorate enough to just fall off inside the flu without chiseling it? We furn a very hot fire that does not produce any smoke 99% of the time in this fireplace insert, so there should not be much residue deposited in the chimney.

Answer
Welcome back William, the mortar will not "fall off" on it own and will reduce the draft. What size flue is that insert running in and what size is the insert collar? if you have a 6" insert collar, going into a 7 x 7 flue you should be ok but you must have it piped to the first flue tile "Minimum"  I do not service any inserts/wood stoves that are not lined to the top with an insulated SS liner.
I would have a local Certified Chimney Sweep www.csia.org, (there you can look up by zip code to find one near you) take a first hand look at what you have, they should be able to help.
Hope this helps
James