Is the recirculator pump new, on a timer, or thermostat. Have you
measured the tenants water temp, many complain, just to be sure they
are getting their rents worth. You only need 106-107 out of the shower
head to take a hot water shower at the furthest point. Im sure your gas
bill is high, your tennants don`t care, you pay for it. I would check
the temp yourself first after you cut it back to 117 or less. You need a
timer and thermostat on circulators or you are just running a heating
system. I hope all your pipes are insulated. If your faucets were
leaking I would worry. You need to be the one to determine what temp is
needed, not your tennnts, its your profit.