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Gas fired heating appliances produce low temperature, high moisture content flue gases which collect as acidic condensate on the inside of oversized, cold masonry chimneys. It is this acidic condensation that is the primary cause of masonry chimney deterioration, which creates a serious health hazard as well as costly repairs.
Other contributing factors are:
A. Is there coal or oil residue within the chimney flue system?
(Tip) This residue contains sulfur which is a catalyst to accelerated deterioration of the masonry chimney and liners.
B. Appliances cycle: they do not operate constantly.
(Tip) Due to this cycling, masonry chimneys seldom warm up sufficiently to prohibit condensation formation, especially if it is an exterior chimney! Light gauge metal chimney liners need very little heat to warm up above condensing temperature.
Why insulate?
There are two main reasons why we always try to insulate our liners.
1. Insulation keeps the flue gases warm, minimizing condensation formation and improving draft.
2. The insulated poly wrap keeps the aluminum liners away from the corrosive sulphuric residue inside the chimney. |