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.
Survey the Odds. Heating and air conditioning professionals often tell clients that under ânormalâ operating conditions, their HVAC system could last between 15 and 25 years. Furnaces tend to outlast air conditioners; cooling units can last up to 20 years, while furnaces can last up to 25 years. The all-important factor in these ranges is regular maintenance.