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.
Air source heat pumps can be expected to achieve 12-18 years while A/C units may last 15-20 years. Ground source heat pumps should achieve an 18-25 year life. Gas and oil furnaces will likely have life expectancies of 15-25 years. Boilers may range from 15 years to well over 30 plus years. The area the units are installed (basements, craw space, attic, etc) will play a factor as well as the demand and usage placed on the equipment. The most important aspect to long life is the quality of the initial installation of the equipment. more.