Alvin, when there is more noticeable progress, I'll report. Still busy building, and working a full-time job.
Mikesolar, Yes, mostly winter, but also for DHW preheat for the rest of the year.
Also, thanks for the pump link. A question: are the pumps usually that expensive? I'm a little nervous about the price considering that I haven't calculated my return.
I do realize that if the cost was factored over 10 years, then it's not so much.