diff --git a/Utilities/Matlab/FDS_verification_dataplot_inputs.csv b/Utilities/Matlab/FDS_verification_dataplot_inputs.csv
index 537d74d33c8..0b401951b0a 100644
--- a/Utilities/Matlab/FDS_verification_dataplot_inputs.csv
+++ b/Utilities/Matlab/FDS_verification_dataplot_inputs.csv
@@ -465,6 +465,8 @@ d,ns2d_8_nupt1,NS_Analytical_Solution/ns2d_8_nupt1_git.txt,NS_Analytical_Solutio
 d,ns2d_16_nupt1,NS_Analytical_Solution/ns2d_16_nupt1_git.txt,NS_Analytical_Solution/ns2d_16_nupt1_exact.csv,1,2,Time,u-vel,Analytical (u-vel),k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,NS_Analytical_Solution/ns2d_16_nupt1_devc.csv,2,3,Time,UVEL,FDS (UVEL),k--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Velocity (ns2d\_16\_nupt1),Time (s),Velocity (m/s),0,7,1,0.3,2.4,1,no,0.05 0.90,NorthEast,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/ns2d_16_nupt1,Convergent Series,end,0,NS Analytical Solution,kd,k,TeX
 d,ns2d_32_nupt1,NS_Analytical_Solution/ns2d_32_nupt1_git.txt,NS_Analytical_Solution/ns2d_32_nupt1_exact.csv,1,2,Time,u-vel,Analytical (u-vel),k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,NS_Analytical_Solution/ns2d_32_nupt1_devc.csv,2,3,Time,UVEL,FDS (UVEL),k--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Velocity (ns2d\_32\_nupt1),Time (s),Velocity (m/s),0,7,1,0.3,2.4,1,no,0.05 0.90,NorthEast,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/ns2d_32_nupt1,Convergent Series,end,0,NS Analytical Solution,kd,k,TeX
 d,ns2d_64_nupt1,NS_Analytical_Solution/ns2d_64_nupt1_git.txt,NS_Analytical_Solution/ns2d_64_nupt1_exact.csv,1,2,Time,u-vel,Analytical (u-vel),k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,NS_Analytical_Solution/ns2d_64_nupt1_devc.csv,2,3,Time,UVEL,FDS (UVEL),k--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Velocity (ns2d\_64\_nupt1),Time (s),Velocity (m/s),0,7,1,0.3,2.4,1,no,0.05 0.90,NorthEast,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/ns2d_64_nupt1,Relative Error,mean,0.01,NS Analytical Solution,kd,k,TeX
+d,obst_activation_ulmat,Pressure_Solver/obst_activation_ulmat_git.txt,Pressure_Solver/obst_activation_exact.csv,1,2,Time,TEMP,Analytical (TEMP),k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pressure_Solver/obst_activation_ulmat_devc.csv,2,3,Time,TEMP,FDS (ULMAT),k--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Temperature (obst\_activation),Time (s),Max Temperature (°C),0,2,1,19.5,20.5,1,no,0.05 0.90,SouthEast,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/obst_activation,Absolute Error,max,0.5,Pressure Solver,kd,k,TeX
+f,obst_activation_default,Pressure_Solver/obst_activation_default_git.txt,Pressure_Solver/obst_activation_exact.csv,1,2,Time,TEMP,Analytical (TEMP),k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pressure_Solver/obst_activation_default_devc.csv,2,3,Time,TEMP,FDS (FFT),ko--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Temperature (obst\_activation),Time (s),Max Temperature (°C),0,2,1,19.5,20.5,1,no,0.05 0.90,SouthEast,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/obst_activation,Absolute Error,max,0.5,Pressure Solver,kd,k,TeX
 d,obst_coarse_fine_interface,Pressure_Effects/obst_coarse_fine_interface_git.txt,Pressure_Effects/obst_coarse_fine_interface_exact.csv,1,2,Time,DP,Analytical (DP),k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pressure_Effects/obst_coarse_fine_interface_devc.csv,2,3,Time,DP,FDS (DP),k--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Background Pressure (obst\_coarse\_fine\_interface),Time (s),Pressure (Pa),0,10,1,-10,10,1,no,0.05 0.90,NorthEast,,1,linear,FDS_User_Guide/SCRIPT_FIGURES/obst_coarse_fine_interface,Absolute Error,end,2,Pressure Effects,kd,k,TeX
 d,opening_ulmat,Pressure_Solver/opening_ulmat_git.txt,Pressure_Solver/opening_pressure_error.csv,1,2,Time,Pressure Tolerance,Ideal (Pressure Tolerance),ko--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pressure_Solver/opening_ulmat_devc.csv,2,3,Time,perr-max,FDS (p err max),k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pressure Error (opening\_ulmat),Time (s),Pressure Error (Pa),0,10,1,0,1.00E-06,1,no,0.05 0.90,SouthEast,,1,semilogy,FDS_User_Guide/SCRIPT_FIGURES/opening_ulmat,Absolute Error,tolerance,1.00E-10,Pressure Solver,k+,k,TeX
 d,parabolic_profile,Flowfields/parabolic_profile_git.txt,Flowfields/parabolic_profile.csv,1,2,Time,Pressure,Exact (Pressure),ko,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Flowfields/parabolic_profile_devc.csv,2,3,Time,pres,FDS (pres),k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pressure (parabolic\_profile),Time (s),Pressure (Pa),0,60,1,0,2500,1,no,0.05 0.90,SouthEast,,1,linear,FDS_User_Guide/SCRIPT_FIGURES/parabolic_profile,Relative Error,end,0.01,Pressure Effects,k+,k,TeX
diff --git a/Verification/FDS_Cases.sh b/Verification/FDS_Cases.sh
index 0545ce9ba32..eaa1f90ea07 100755
--- a/Verification/FDS_Cases.sh
+++ b/Verification/FDS_Cases.sh
@@ -405,6 +405,7 @@ $QFDS -p 8 -d Pressure_Solver pressure_iteration3d_uglmat.fds
 $QFDS -p 16 -d Pressure_Solver random_obstructions_fft.fds
 $QFDS -p 4 -d Pressure_Solver stairwell.fds
 $QFDS -p 2 -d Pressure_Solver ulmat_2zone.fds
+$QFDS -p 4 -d Pressure_Solver obst_activation_default.fds
 $QFDS -p 4 -d Pressure_Solver obst_activation_ulmat.fds
 
 $QFDS -d Pyrolysis cable_11_insulation_mcc.fds
diff --git a/Verification/Pressure_Solver/obst_activation_default.fds b/Verification/Pressure_Solver/obst_activation_default.fds
new file mode 100644
index 00000000000..0d1ef17ee7e
--- /dev/null
+++ b/Verification/Pressure_Solver/obst_activation_default.fds
@@ -0,0 +1,49 @@
+&HEAD CHID='obst_activation_default', TITLE='Test of various obst activation situations for default FFT Poisson solver.' /
+
+&MESH IJK=16,1,16, XB=0.0,0.8,-0.001,0.001,0.0,0.8 /
+&MESH IJK=16,1,16, XB=0.8,1.6,-0.001,0.001,0.0,0.8 /
+&MESH IJK=16,1,16, XB=1.6,2.4,-0.001,0.001,0.0,0.8 /
+&MESH IJK=16,1,16, XB=2.4,3.2,-0.001,0.001,0.0,0.8 /
+
+&TIME T_END=2.0 /
+
+&PRES CHECK_POISSON=T /
+
+&MISC SIMULATION_MODE='DNS', STRATIFICATION=.FALSE. /
+&RADI RADIATION=F /
+
+&SPEC ID='LJ AIR', VISCOSITY=1.2E-5, BACKGROUND=.TRUE. /
+
+&SURF ID='WALL', FREE_SLIP=.TRUE., DEFAULT=.TRUE. /
+&SURF ID='PLATE', NO_SLIP=.TRUE. /
+
+&DEVC ID='clock_1', XYZ=0,0,0, QUANTITY='TIME', SETPOINT=0.3, INITIAL_STATE=F /
+&DEVC ID='clock_2', XYZ=0,0,0, QUANTITY='TIME', SETPOINT=0.5, INITIAL_STATE=T /
+&DEVC ID='clock_3', XYZ=0,0,0, QUANTITY='TIME', SETPOINT=0.8, INITIAL_STATE=F /
+&DEVC ID='clock_4', XYZ=0,0,0, QUANTITY='TIME', SETPOINT=1.0, INITIAL_STATE=T /
+&DEVC ID='clock_5', XYZ=0,0,0, QUANTITY='TIME', SETPOINT=1.2, INITIAL_STATE=F /
+&DEVC ID='clock_6', XYZ=0,0,0, QUANTITY='TIME', SETPOINT=1.5, INITIAL_STATE=T /
+
+&OBST XB=0.1,0.2,-0.001,0.001,0.3,0.5, SURF_ID='PLATE', DEVC_ID='clock_1' /
+&OBST XB=1.4,1.6,-0.001,0.001,0.2,0.4, SURF_ID='PLATE', DEVC_ID='clock_2' /
+&OBST XB=2.4,2.5,-0.001,0.001,0.4,0.6, SURF_ID='PLATE', DEVC_ID='clock_3' /
+&OBST XB=3.0,3.2,-0.001,0.001,0.3,0.5, SURF_ID='PLATE', DEVC_ID='clock_4' /
+&OBST XB=0.6,1.0,-0.001,0.001,0.5,0.7, SURF_ID='PLATE', DEVC_ID='clock_5' /
+&OBST XB=1.9,2.1,-0.001,0.001,0.0,0.1, SURF_ID='PLATE', DEVC_ID='clock_6' /
+
+&SURF ID='BLOW', VEL=-0.5 /
+
+&VENT PBX=0.0, SURF_ID='BLOW' /
+&VENT PBX=3.2, SURF_ID='OPEN' /
+
+&SLCF PBY=0.,QUANTITY='PRESSURE', VECTOR=T /
+&SLCF PBY=0.,QUANTITY='DIVERGENCE', CELL_CENTERED=T /
+&SLCF PBY=0.,QUANTITY='ZONE PRESSURE SOLVER TYPE', CELL_CENTERED=T /
+
+&DEVC ID='TEMP', XB=0.0,3.2,-0.001,0.001,0.0,0.8, QUANTITY='TEMPERATURE', SPATIAL_STATISTIC='MAX', TEMPORAL_STATISTIC='INSTANT VALUE'/
+
+&DUMP DT_DEVC=0.5, SIG_FIGS=6 /
+  
+&TAIL /
+
+
diff --git a/Verification/Pressure_Solver/obst_activation_exact.csv b/Verification/Pressure_Solver/obst_activation_exact.csv
new file mode 100644
index 00000000000..2a335eed96b
--- /dev/null
+++ b/Verification/Pressure_Solver/obst_activation_exact.csv
@@ -0,0 +1,6 @@
+Time,TEMP
+0.0,20.0
+0.5,20.0
+1.0,20.0
+1.5,20.0
+2.0,20.0
diff --git a/Verification/Pressure_Solver/obst_activation_ulmat.fds b/Verification/Pressure_Solver/obst_activation_ulmat.fds
index 59e9eb7a050..dd17b0717d3 100644
--- a/Verification/Pressure_Solver/obst_activation_ulmat.fds
+++ b/Verification/Pressure_Solver/obst_activation_ulmat.fds
@@ -1,4 +1,4 @@
-&HEAD CHID='obst_activation_ulmat', TITLE='Test of various obst activation situations for inseparable ULMAT' /
+&HEAD CHID='obst_activation_ulmat', TITLE='Test of various obst activation situations for inseparable ULMAT.' /
 
 &MESH IJK=16,1,16, XB=0.0,0.8,-0.001,0.001,0.0,0.8 /
 &MESH IJK=16,1,16, XB=0.8,1.6,-0.001,0.001,0.0,0.8 /
@@ -10,6 +10,7 @@
 &PRES CHECK_POISSON=T, SOLVER = 'ULMAT' /
 
 &MISC SIMULATION_MODE='DNS', STRATIFICATION=.FALSE. /
+&RADI RADIATION=F /
 
 &SPEC ID='LJ AIR', VISCOSITY=1.2E-5, BACKGROUND=.TRUE. /
 
@@ -39,6 +40,10 @@
 &SLCF PBY=0.,QUANTITY='DIVERGENCE', CELL_CENTERED=T /
 &SLCF PBY=0.,QUANTITY='ZONE PRESSURE SOLVER TYPE', CELL_CENTERED=T /
 
+&DEVC ID='TEMP', XB=0.0,3.2,-0.001,0.001,0.0,0.8, QUANTITY='TEMPERATURE', SPATIAL_STATISTIC='MAX', TEMPORAL_STATISTIC='INSTANT VALUE'/
+
+&DUMP DT_DEVC=0.5, SIG_FIGS=6 /
+  
 &TAIL /