diff --git a/Source/main.f90 b/Source/main.f90
index 4de1104e8f6..f151d64a0a4 100644
--- a/Source/main.f90
+++ b/Source/main.f90
@@ -482,7 +482,7 @@ PROGRAM FDS
    CALL DIVERGENCE_PART_1(T_BEGIN,DT,NM)
 ENDDO
 
-IF (HVAC_SOLVE .AND. N_ZONE>0 .AND. .NOT.SOLID_PHASE_ONLY) CALL EXCHANGE_DIVERGENCE_INFO
+IF (N_ZONE>0 .AND. .NOT.SOLID_PHASE_ONLY) CALL EXCHANGE_DIVERGENCE_INFO
 
 CALL GLOBAL_MATRIX_REASSIGN(FORCE_REASSIGN=.TRUE.)
 
@@ -1816,11 +1816,11 @@ SUBROUTINE EXCHANGE_DIVERGENCE_INFO
 ! Connect zones to others which are not directly connected
 
 IF (OBST_CREATED_OR_REMOVED) THEN
-   IF (N_MPI_PROCESSES>1) CALL MPI_ALLREDUCE(MPI_IN_PLACE,CONNECTED_ZONES,(N_ZONE+1)**2,MPI_INTEGER,MPI_SUM,MPI_COMM_WORLD,IERR)
+   IF (N_MPI_PROCESSES>1) CALL MPI_ALLREDUCE(MPI_IN_PLACE,CONNECTED_ZONES,(N_ZONE+1)**2,MPI_INTEGER,MPI_MAX,MPI_COMM_WORLD,IERR)
    DO IPZ=1,N_ZONE
       CONNECTED_ZONES = MATMUL(CONNECTED_ZONES,CONNECTED_ZONES)
+      CONNECTED_ZONES = MIN(1,CONNECTED_ZONES)
    ENDDO
-   CONNECTED_ZONES = MIN(1,CONNECTED_ZONES)
 ENDIF
 
 T_USED(11)=T_USED(11) + CURRENT_TIME() - TNOW