Part 4/9:
To gather evidence of just how oversized their furnace was, the homeowner conducted an experiment using smart thermostats and energy monitoring devices. They documented how long the furnace needed to run during exceptionally cold weather. An efficient gas furnace, while robust in its capabilities, showed that for most of the winter, it operated for only a small fraction of its potential. One instance revealed that on the coldest of days, it only needed to run for 6 out of 24 hours, suggesting a demand of merely 25% of its capacity—even when temperatures were dangerously low.