I really enjoying the discussions on this site. I'm currently reading many of the DIY HVAC discussions. I'm an electrical engineer with 25 years of experience. I got my EPA Clean Air Section 608 certification a few years ago and have done basic HVAC - check charge, replace start capacitor, etc. for many years now. I'm now considering replacing my 15 year old, burnt out (compressor), 3 ton, 13 SEER, heat pump that was installed by a pro, and always serviced by a pro. Possibly with help from a pro but I'm considering doing at least the mechanical installation on my own. No doubt I'll be asking questions as I think this through. I'm looking forward to the conversations.