Energy Star puts typical duct losses at 20 to 30 percent of the air moving through the system. Why that mimics an undersized system, how to tell whether to fix the ducts or replace the equipment, and what a real assessment involves.
AFUE and HSPF2 are different units and cannot be compared directly. What actually decides between a heat pump, a gas furnace and dual fuel: design temperature, the local fuel price ratio, and what is already in the house.
SEER2 is not a worse SEER. It is the same idea under a harder test. What changed in 2023, the regional minimums, how to tell whether a higher-efficiency upcharge pays back, and what breaks the math.
A refrigerant rule changed this decision in 2025, and not because the equipment changed. What the AIM Act phasedown actually requires, why the failed component matters more than the system age, and the arithmetic.
Most maintenance lists give no indication of which items matter. Two prevent the failures that strand people in August, several are homeowner jobs, and a maintenance plan is a retention product. Sorted by consequence.
Oversizing is a very common installation fault in American homes, it is invisible on the invoice, and it makes a house less comfortable. What short-cycling does, what a Manual J calculation is, and how to tell whether you are getting one.
