The rating is a ratio, not a grade
HSPF and SEER are both a measure of heat moved against electricity spent. A higher number means the compressor is pulling more heat out of the outside air for the same watt-hour, not that the unit is bigger or stronger. Two systems can heat the same house to the same temperature and still land on opposite ends of that ratio, because one compressor is doing the job with less electricity than the other.







