Expert: James Ball - 6/23/2011

Question
QUESTION: We have a wood burning insert that was installed about 10 years ago, at the same time we had a flu liner placed in the chimney. The chimney sweep who came today found that several parts in the insert had rusted and need to be replaced.  The insert is in a basement level that is finished and regularly heated and air conditioned.  We run 2 portable dehumidifiers down there in the summer-- Large room.  The humidity is usually between 40 and 50%. The adjoining chimney flu is for a fireplace on the middle level and it has a heatalator with glass doors.  There is often condensation on the fireplace side of the glass doors on humid days with the AC set at 73.  What is causing this humidity and is there anything we can do to prevent damage to the fireplace units? Thank you.

ANSWER: Hello Emily, during the winter you are using the unit so it heats the area around it, in the summer you are not, if this is below grade then the all the brick and masonry will be cold and damp.
you might have a leak some where in the chimney system, it might be ground water seeping up. 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


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

QUESTION: That sounds reasonable regarding the basement level, but the glass doors on the above ground level fireplace show condensation on the inside,,,I think both fireplaces issues are caused by the same thing. What could that be?

ANSWER: Welcome back Emily, once moisture gets into the masonry  it will, effect the fireplace above it as it is the same structure, you might have to install "weeping drains" out side to channel the water from the house.
James

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

QUESTION: We have weeping drains around the entire house that were installed when we built.  There is drain tile with gravel under and around it. It drains away from the house on two different corners, so I don't think that is the problem.  Can you think of any other cause other than ground water? We don't think ground water is the problem. Thanks!

Answer
Well, if it is not coming from the ground then it must be coming down from the top (or another area of the roof) into the chimney, you may need to remove the stove and look, you may need to run a hose in the gutters to their under ground drains, then clog and over flow the gutters, then slowly move up the roof to the top of the chimney and watch so see if the water comes in. (moving the hose after running full blast for 20 minutes or more in each area and only moving it 3-5 feet up at a time.
last, are you heating with natural gas? you could have a blockage that is backing up the moisture, get a certified sweep in there to inspect it
hope this helps
James