draft decreased over time in metalbestos chimney

Bill,
is the chimney located on the gable side of the gambrell roof or the tin side?
do you have windy conditions creating air currents swirling at the chimney top causing down drafts?
I know, but pictures do help answer many questions. do you have someone to help show you how to load pics.

I get the impression that the original poster has lost draft over time which leads me to think that we are missing something. I think that chimney needs a thorough going over to look for breeches, pin holes, a clog, something that gradually diminished his draft. Is there a clean out that could be rotton or not sealed??

Does the top of the chimney rise above the height of the cupola?
If the house has opened up over time the cupola is fighting the chimney for draft...
Once the chimney is top dog it will once again draft properly...
Run a bright light down the chimney on a dark night just bto be sure...
The cleanout on the TEE going into the house has a cremovable plate...
It tends to rot and would be a good place to check...

o.k.
the chimney is on the tin side of the gambrell roof and no the chimney does not stand taller than the cupola and i did disasemble and inspect the chimney i even replaced a 4 foot section due to a minor buckle in the side wall creosote at one time must have ignighted to cause a buckle like that so the chimney is in A1 shape and now for wind the prevailing wind comes from the west and briskly most of the time it blows past me down into the valley below at the lake as i mostly see the smoke heading east its interesting that the height of the chimney never was a problem not being higher than the cupola before i started having the problem again it seems that an inducer will clear the problem up i just don,t know if you need a baro with the inducer and if you do does the inducer go before or after the baro as my greatest fear is co gas as with my wood stove i have been woken up to a house full of smoke once and awhile its scary and damn it I don,t wan,t to end up a cold smoked ham!!!

With the venting system under your metal roofing, it would be interesting to see what readings a manometer would give holding the manommeter outdoors with the tube inserted into the inside of the building.

Wind pressures outside around a building can have some amazing effects. And like the wind...pressures are not always the same. One end could have positive wind pressure while the opposite end could be experiencing negitive at the same time...but both not always equal in strenth.

put a 4' extension on it, make sure your cleanout and joints are sealed tightly and you won't need a draft inducer. after thermal cycling, sometimes the stainless chimney's don't seal well at the joints; yet another reason not to use stainless. make sure the stack is higher than the highest portion of the home. A properly built chimney of the proper height will NEVER need a draft inducer. Fix the problem(s) don't apply a bandaid.

Metal chimney .... coal ash .... outdoors ....

My bet is on holes up & down the chimney from corrosion, cleaned or not.