I moved my mega-stor the other day and eliminated a zone valve and relay. It's on a seperate loop with its own circulator so I figure it doesn't need a zone valve. Now it seems to be thermosiphoning. I had the aquastat turned all the way down yet the water temp was about 120*F. The supply and return piping stayed hot even though the circ. was not running. I've never dealt with this issue before. Is it common? Any input would be appreciated.