[Ron342]

Reading AC's earth tube success story makes me wonder if the basic earth tube idea would work for the outside unit of an existing air supply heat pump?? Or A/C unit. Please excuse the attached drawing!
One would simply need to trench in a wagonwheel pattern (or whatever would fit around your existing heat pump or A/C) of buried 4" or 6" earth tubes leading to the bottom of an annular jacket fitted completely around the outside of your then encircled heat pump condenser/evap fins. Most outside units are round or rounded squares so not too hard. Seal the annular top of the jacket, slope the earth pipes for condensate drains and your existing outside unit fan would pull its air only thru the heat tubes, into the bottom of the annular jacket and up thru it, thru the existing fins and out its existing center exit both winter and summer.
Nothing new inside your house, no mold/mildew worries, no hvac lines to break & move, a days trencher rent (or a teenager you need to keep busy!), $200 of maybe 4" Schedule 20 pvc pipe and a day to make the jacket - assuming no rocks! Would have to be better than exchanging with 20 degree outside air in winter and 90 degree in summer?????

My next project, I think.