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.
Heat Output. The most direct way to compare the heating capability of a propane furnace is to refer to the heat-output ratings. These ratings are given in British Thermal Units, and they measure how much heat the furnace can produce per hour. Output ratings generally range from about 40,000 BTU to 120,000 BTU per hour.he most direct way to compare the heating capability of a propane furnace is to refer to the heat-output ratings.