If its a prefab steel chimney there is not much that can happen. A little bit of soot might stick to it but that is just carbon. If its masonary it might not be a bad idea to get it checked every couple years to make sure all the tiles are still in tact and all that stuff.
Unless the logs are setup totally wrong and the thing is producing massive ammounts of soot I don't see why one should ever need to get it cleaned.
they can on rare occasion, totally block a flue. However, I agree since it is virtually pure carbon, the risk is for the migration of "black stuff" into areas you don't want it such as all over the house. Since most modern houses have a little negative pressure, it is not uncommon for "soot" to fall down the chimney into the room. Once its out in the home, we call it BPM--Black Particulate Matter. Can cost $30K to clean up. That's the price of a case I'm handing right now from a VF gas logset. That price does not include the $10K to tear out the old Fp and install a new one. I'm aware of one that ran over $60K.
Thanks for the quick replies guys. This section has been a little uneventful recently with weather in the 60's. I am glad to see everyone is still around.
JTP, I rarely see a large abount of soot built up on vented logs, except in some propane units.
hearthman, that is a pretty healthy sum to clean up BPM. I have heard numbers only as high as 18k, but 3-6k is about average. What was the cause of the bpm, pet fur and lint?log placement? Why would one have to replace the whole unit?
NFPA211 says inspect annually and clean if necessary. Gas logs should not generate a lot of soot but the water vapor, released by the burning of the gas, can cause a terra cotta flue tile to disintegrate. If enough chunks of the flue tile spall off, they can block your flue.