Originally Posted By: pbolliger
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Keep this in mind also, that any natural / propane gas burning appliance “should” not be (connected) mixed with any wood burning appliance to chimneys. I hope this chimney is lined with a flue liner.
Since natural/ propane burns at a lower temp then wood. Moisture (condensate) from the combustion products accumulate inside the unlined (perhaps oversize too) chimney and behaves as an acid to the mortar holding the bricks.. Can you say chimney failure. ![icon_sad.gif](upload://nMBtKsE7kuDHGvTX96IWpBt1rTb.gif)
In general a "smoke pipe" (some call it a flue pipe or stove pipe) should slope upward 1/4" per foot up to chimney.
As for the gap that various smoke pipes should have , a class "b" vent (double wall) is 1-2 " inches where as a single wall is 6" inches of clearance to combustible material.
I trained at the local gas company regarding natural gas burning appliances and found that many installation can be dangerous with respect to CO generation.
The room size (general idea) and type of appliance (category) should always be checked as should the "smokepipe / flue" . We can't see chimney liners at times but should you suspect that a "change" in heating equipment was done it would be worth while to look at more closely..