Myth #2 I have a carbon monoxide alarm so I'll just wait until that goes off to determine when it's time for a new furnace. Okay, then wait until your smoke detectors go off before you fix those faulty wires in your wall. Many times a heat exchanger that has areas of concern or a crack will not emit CO. However, according to the AGA (American Gas Association) any visible failure is reason to repair or replace.
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