diff --git a/Source/smokeview/menus.c b/Source/smokeview/menus.c
index 08b9c24c0f..1c021f06ab 100644
--- a/Source/smokeview/menus.c
+++ b/Source/smokeview/menus.c
@@ -2005,7 +2005,12 @@ void RenderState(int onoff){
   int scale = 1;
 
   if(onoff==RENDER_ON){
+    int n;
+
     if(render_status == RENDER_ON)return;
+    for(n = 0; n < nglobal_times; n++){
+      render_frame[n] = 0;
+    }
     render_status = RENDER_ON;
     render_firsttime = YES;
     update_screeninfo = 1;
diff --git a/Source/smokeview/update.c b/Source/smokeview/update.c
index a0f7f0360c..7207b12f70 100644
--- a/Source/smokeview/update.c
+++ b/Source/smokeview/update.c
@@ -635,6 +635,7 @@ void UpdateShow(void){
   }
   if(showsmoke==1||showpatch==1||showslice==1||showvslice==1||showzone==1||showiso==1)RenderTime=1;
   if(showtours==1||show3dsmoke==1||touring==1||showvolrender==1)RenderTime=1;
+  if(showhvacflag == 1)RenderTime = 1;
   if(showshooter==1)RenderTime=1;
   if(plotstate==STATIC_PLOTS&&nplot3dloaded>0&&plotn>0&&plotn<=numplot3dvars)showplot3d=1;
   if(showplot3d==1){