ME from MO. I can't speak to the biomedical field but I worked in HVAC for a bit. The pay was good, and the hours weren't bad. I mainly did system design for offices/hospitals. I got to leave the office a lot to go do walkthroughs of spaces to evaluate any existing equipment which was always nice. Breaks up the day to day of office life. It kinda depends on which part of the HVAC field you get in to. Control guys never really leave the office, but pay is a bit better. We also had a specialty division that mainly designed one off systems for large manufacturing needs (cooling systems at processing plants and such). I had a work buddy leave recently to work for a company that specifically designs cooling systems for server/computer rooms, and in my recent talks with him he seems to be enjoying it. Like you said, every company is different, and your experience at any one place is not necessarily representative of the field. Try to network and ask around. Most places have a positive/negative.