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.
A well manufactured machine that lasted, with an average life of 17-19 years. The machine was very simple, operating with knobs, buttons, belts and they were easily serviced. Appliances now last about half that time for a variety of reasons. First is energy efficiency. In the 1980s, California initiated the first energy efficiency laws. In order for products to be sold, they would meet certain requirements. That program would morph into todays national EnergyStar program.