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.
What Is the Life Span of a Furnace? Have you been limping an aging heating system along for a couple of heating seasons and racking up high heating bills? The average furnace life span is approximately 15 years, though it can range from 13 to 20 years. While the equipment may last that long, itâs likely that your heating bills are higher than they need to be, since furnaces lose efficiency as they age.