From 331bae2f48a7dbce7429074026ced52c7887f296 Mon Sep 17 00:00:00 2001
From: Jason Floyd <drjfloyd@gmail.com>
Date: Sat, 14 Mar 2026 08:58:20 -0400
Subject: [PATCH] FDS Source: Fix order of operations issue with prior commit.

---
 Source/hvac.f90 | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/Source/hvac.f90 b/Source/hvac.f90
index 28ed9c307b..a9e7a31b78 100644
--- a/Source/hvac.f90
+++ b/Source/hvac.f90
@@ -1442,8 +1442,8 @@ SUBROUTINE HVAC_CALC(T,DT,FIRST_PASS)
    DO NN=1,N_DUCTNODES
       DUCTNODE(NN)%ZZ_OLD = DUCTNODE(NN)%ZZ
    ENDDO
-   CALL ADJUST_LEAKAGE_AREA
    CALL FIND_NETWORKS(CHANGE,T) ! calls determined fixed elements (which calls update fan for fixed fans)
+   CALL ADJUST_LEAKAGE_AREA
    IF (N_NETWORKS == 0) RETURN
    IF (HVAC_QFAN .OR. HVAC_MASS_TRANSPORT) CALL FIND_DUCTRUNS(CHANGE)
 ELSE FIRST_PASS_IF !Not FIRST_PASS, reset variables to old solution
@@ -2816,6 +2816,7 @@ SUBROUTINE FIND_NETWORKS(CHANGE,T)
 DO ND = 1, N_DUCTS
    IF(DUCT_COUNTER(ND) > 0) NETWORK(DUCT_COUNTER(ND))%N_DUCTS = NETWORK(DUCT_COUNTER(ND))%N_DUCTS + 1
 ENDDO
+
 DO NN = 1, N_DUCTNODES
    IF(NODE_COUNTER(NN) > 0) NETWORK(NODE_COUNTER(NN))%N_DUCTNODES = NETWORK(NODE_COUNTER(NN))%N_DUCTNODES + 1
 ENDDO
@@ -2847,6 +2848,7 @@ SUBROUTINE FIND_NETWORKS(CHANGE,T)
 
 END SUBROUTINE FIND_NETWORKS
 
+
 !> \brief For each HVAC network the routine defines which ducts and nodes belowng to which element of the HVAC matrix
 
 SUBROUTINE SETUP_SOLUTION_POINTERS
@@ -3695,6 +3697,7 @@ SUBROUTINE ADJUST_LEAKAGE_AREA
 DO ND=1,N_DUCTS
    DU => DUCT(ND)
    IF (.NOT.DU%LEAKAGE .AND. .NOT.DU%LOCALIZED_LEAKAGE) CYCLE
+   IF (DU%AREA<TWENTY_EPSILON_EB) CYCLE
    DELTA_P = ABS(DUCTNODE(DU%NODE_INDEX(1))%P-DUCTNODE(DU%NODE_INDEX(2))%P)
    IF (DU%LOCALIZED_LEAKAGE) THEN
       DELTA_P_REF = DU%LEAK_REFERENCE_PRESSURE
@@ -3705,7 +3708,7 @@ SUBROUTINE ADJUST_LEAKAGE_AREA
       N = P_ZONE(DUCTNODE(DU%NODE_INDEX(2))%ZONE_INDEX)%LEAK_PRESSURE_EXPONENT(DUCTNODE(DU%NODE_INDEX(1))%ZONE_INDEX)
       C_D = P_ZONE(DUCTNODE(DU%NODE_INDEX(2))%ZONE_INDEX)%DISCHARGE_COEFFICIENT(DUCTNODE(DU%NODE_INDEX(1))%ZONE_INDEX)
    ENDIF
-   DU%AREA = C_D * DU%AREA_INITIAL * (DELTA_P/DELTA_P_REF)**(N-0.5_EB)
+   DU%AREA = C_D * DU%AREA * (DELTA_P/DELTA_P_REF)**(N-0.5_EB)
 ENDDO
 
 END SUBROUTINE ADJUST_LEAKAGE_AREA