Over the last couple of weeks I have installed the solar hot water piping runs from the third floor drain-back tank room to the mechanical room on the first floor. The drain back tank is on the third floor in its own little mechanical room to improve the electrical efficiency of the system. The pump has to work harder to restart the system after it has drained back and the shorter the distance between the drain back tank and the panels the less the pump has to work.
Installing the pipes was quite easy with the help of my plumber’s ProPress. Rather than soldering all of the fittings this tool–along with its associated specialized fittings uses rubber O-rings and compression to make a seal.

Solar hot water pipe run under third floor stairs. The aren't parallel because I ran out of soft copper. I was creating 60 degree bends whereas you can only purchase 45 and 90 fittings. We had the soft copper for use in the area where the pipe ran through the roof insulation--this way we avoided any fittings in an area that we don't want to ever have to disassemble.

Before we take down the staging to the solar hot water panels or cover any of the pipes with insulation, we wanted to make sure there were no leaks. We capped off one end and put this gauge/schrader valve combination on the other. The panel loop held 80 psi for several days (an hour would have sufficed). It was neat to see it oscillate between 70 psi at night and 80 during the day.