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.
How long should my HVAC system last? February 24, 2011 â Art Avent, hvac advice. Among manufacturers, you are unlikeley to find anything definitive in writing on this question, but my personal opinion is that an electric heat pump & air conditioner SHOULD last 12-15 years & a gas furnace SHOULD last 15-20 years or more. Truth is, they last anywhere between 1 â 20 years.