Another thing that people often point to as a negative thing about ketosis is that people can suffer symptoms such as headaches and dizziness in the first few days of a ketogenic diet. Also, athletic performance can suffer until the body adapts to using fat for energy instead of glucose.
Forced air furnace heat exchangers have an average life expectancy of 15 years, with a range typically between 13 and 20 years. Most heat exchangers used in models today today will last between 15 and 25 years and are usually made from aluminized or stainless steel.
Time's Up. Generally speaking, a furnace can be expected to last between 15 and 20 years. This average varies, of course, based on the quality of the unit, how it's used and whether it has been properly maintained.ime's Up. Generally speaking, a furnace can be expected to last between 15 and 20 years. This average varies, of course, based on the quality of the unit, how it's used and whether it has been properly maintained.