Thank you for the useful basic information... much better than raving
'experts' who take the time for flame, but don't themselves provide
useful information.

A continues search found:
http://www.energyoutlet.com/res/heat...fficiency.html
which states:
snip
"A heat pump with an HSPF of 6.8 has an "average COP" of 2 for the
heating season. To estimate the average COP, divide the HSPF by 3.4.
"Don't assume the HSPF will be an accurate predictor of your actual
installed performance. HSPF assumes specific conditions that, are
unlikely to coincide with your climate. "
snip

I assume the COP is equal to the AFUE (except the AFUE is normally
expressed in terms of %). Is that fairly accurate?