Its like Carrier and their 96.7% furnace, only one is 96.7% efficient,
the smallest unit a 38000 btu unit, which few need such a small size,
they acheive it by adding 20 lb or so of metal than the next higher
output size.

Ok so 19.5 is the highest in that line but the real point was Wes
thought 14 seer was Tranes most efficient line up when in fact there are
several better than 14 seer