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.
Furnace Lifespan. The average service life of a new furnace is 15 to 20 years. Most furnace parts that fail during that span are replaceable at a cost that makes repair a better call than replacing the entire furnace. The exception is the heat exchanger, a furnace's single most expensive component.ew air conditioning and heating equipment lasts longer than ever. The end of a furnace's or air conditionerâs service life depends on more than just chronological age. Energy-efficiency issues and the price of any necessary repairs versus the cost of upgrading to a new unit all enter into that determination.