A family member has developed health problems including anemia and thyroid problems that cause them to feel cold all the time.
As a result we have to keep the heat at between 78 to 80°. When this first started a couple years ago the furnace heat exchanger cracked within six months of turning the heat to this level.
This was on a 90,000 btu 80% natural gas furnace. After that happened we got a 95% efficiency natural gas furnace and about a year after running it we have noticed problems with it.
Is there a type of furnace that is designed to withstand these demanding heating needs without breaking? Our home is 1700 ft. Two stories.