ccu4flow: improve ma7 release nv hack

tcl/drivers/ccu4flow.tcl

@@ -405,7 +405,7 @@ proc ccu4flow::ctrl {} {
         set regstate 0
       }
     } else {
-      if {[silent 0 sct release_blocked]} {
+      if {[silent 0 sct release_blocked] && $ist > $soll + $tol} {
         # hack for releasing n.v. at MA7
         setstate closed
         set closecnt [silent 1 sct closecnt]