Closed loop system using glycol antifreeze, has 6 zone valves. Set pressure to 15# and within a week it drops to 10#. Set to 15# again and drops to 10# again.No visible leaks, but some pipes in wall and under a slab of cement. Is their a sealer I can put in the system?

Keith Nergaard, September 2009

Get some one who can put pressure test on system.
not recomened to add leak seal to your system

joe, September 2009