Silver lining for chimney a good idea for new furnaces

Here’s a relatively new product that’s vital for a safe and comfortable home.

I’m referring to what’s called a flexible chimney liner. Flue or chimney liners protect masonry chimneys from the corrosive effects of flue gases. Flue gases are acidic and eat away the mortar joints of unlined chimneys.

While driving through your neighborhood, you may notice a few of these poking up out of the chimney tops. Those are usually neighbors who have recently installed a new, higher efficiency furnace. Here’s why these are so important.

If a furnace is vented into a potentially oversized and unlined masonry chimney, exhaust gases can cool quickly and condense on the inside walls. The acidic gases will, in time, eat away (or deteriorate if you feel more comfortable with that term) the masonry chimney — causing health hazards and costly repairs. In layman’s terms, the mortar between the bricks rot away, and resulting in blockages or complete chimney failure.

This flexible metal lining protects the chimney by actually creating a new chimney within the old one. It travels from the top all the way down to the basement or area where the furnace is. The furnace and/or the water heater are then joined together in a T shape and attached to the chimney liner, creating a new exhaust portal that prevents damage to your existing masonry.

Chimney liners like these have been required by state code for almost 15 years now. The only ones exempt are houses that already have steel-type chimneys, called b-vent, or if a masonry chimney is not being used by either a furnace or a water heater.

A chimney liner can save you money — and it can save your health.

Joel Wensley is a licensed mechanical contractor in the state of Michigan, a WJBK-TV Fox2 Detroit news contributor and president of Mechanical Heating & Cooling in Dearborn Heights.