diff --git a/Source/hvac.f90 b/Source/hvac.f90
index 8bfcac63fc2..90d4457570b 100644
--- a/Source/hvac.f90
+++ b/Source/hvac.f90
@@ -1297,9 +1297,11 @@ SUBROUTINE INIT_DUCT_NODE
 USE PHYSICAL_FUNCTIONS, ONLY: GET_ENTHALPY
 USE MATH_FUNCTIONS, ONLY: EVALUATE_RAMP
 REAL(EB) :: ZZ_GET(1:N_TRACKED_SPECIES) !< Species mass fraction array.
+REAL(EB) :: VF(1:N_TRACKED_SPECIES) !< Species volunme fraction array.
 REAL(EB) :: TNOW !< Current CPU time (s) used in computing length of time spent in HVAC routines.
 INTEGER :: NN,N
 TYPE(DUCTNODE_TYPE), POINTER :: DN
+TYPE(INITIALIZATION_TYPE), POINTER :: IN
 
 TNOW = CURRENT_TIME()
 
@@ -1332,11 +1334,18 @@ SUBROUTINE INIT_DUCT_NODE
 
    INIT_LOOP: DO N = 1,N_INIT
       IF (TRIM(INITIALIZATION(N)%NODE_ID)==TRIM(DN%ID)) THEN
-         DN%ZZ0 = INITIALIZATION(N)%MASS_FRACTION
-         IF (INITIALIZATION(N)%TEMPERATURE > 0._EB) THEN
-            DN%TMP0 = INITIALIZATION(N)%TEMPERATURE
-         ELSE
-            DN%TMP0 = DN%TMP
+         IN => INITIALIZATION(N)
+         IF (IN%VOLUME_FRACTIONS_SPECIFIED) THEN
+            VF(2:N_TRACKED_SPECIES) = IN%VOLUME_FRACTION(2:N_TRACKED_SPECIES)
+            VF(1) = 1._EB - SUM(VF)
+            DN%ZZ0 = VF(1:N_TRACKED_SPECIES)*SPECIES_MIXTURE(1:N_TRACKED_SPECIES)%MW / &
+                                          SUM(VF(1:N_TRACKED_SPECIES)*SPECIES_MIXTURE(1:N_TRACKED_SPECIES)%MW)
+         ELSEIF (IN%MASS_FRACTIONS_SPECIFIED) THEN
+            DN%ZZ0(2:N_TRACKED_SPECIES) = IN%MASS_FRACTION(2:N_TRACKED_SPECIES)
+            DN%ZZ0(1) = 1._EB - SUM(DN%ZZ0(2:N_TRACKED_SPECIES))
+         ENDIF       
+         IF (IN%TEMPERATURE > 0._EB) THEN
+            DN%TMP0 = IN%TEMPERATURE
          ENDIF
          EXIT INIT_LOOP
       ENDIF