diff --git a/app.py b/app.py
index e60f9d1..c6b4c86 100644
--- a/app.py
+++ b/app.py
@@ -31,7 +31,6 @@ pio.templates["plotly_light"].layout['yaxis']['zerolinecolor'] = 'lightgray'
 ELM = {
   'name': 'tempplot',
   'filedir': './data',
-  # 'filename': './data/20260420213656.txt',
   'filename': None,
   'label_file_fmt': 'File: {filename}',
   'label_data_len_fmt': 'Data points: {num:,} (rendered) / {numa:,} (total)',
@@ -56,6 +55,8 @@ def main_cli():
     '--host', type=str, default='', help='default 127.0.0.1')
   parser.add_argument(
     '--port', type=str, default='8085', help='default 8080')
+  parser.add_argument(
+    '--dir', type=str, default='./data', help='default ./data')
   parser.add_argument(
     '-v', '--verbose', action='store_true', help='Verbose output')
   parser.add_argument(
@@ -86,7 +87,7 @@ def np2pgo(x, y, label=None):
   return res
 
 async def pick_file() -> None:
-  result = await local_file_picker.local_file_picker('./data', multiple=False)
+  result = await local_file_picker.local_file_picker(ELM['filedir'], multiple=False)
   # ui.notify(f'You chose {result}')
   if result:
     filename = result[-1]
@@ -251,12 +252,12 @@ def index():
     ui.label('Heater')
     ELM['number_heat_min'] = \
       ui.number(
-        label='min', value=None, format='%.2f', min=0, step=1.0, suffix='%') \
+        label='min', value=0, format='%.2f', min=0, step=1.0, suffix='%') \
         .props('clearable').classes('w-32').on(
           'update:model-value', lambda e: update_fig(), throttle=1.0)
     ELM['number_heat_max'] = \
       ui.number(
-        label='max', value=None, format='%.2f', min=0, step=1.0, suffix='%') \
+        label='max', value=100, format='%.2f', min=0, step=1.0, suffix='%') \
         .props('clearable').classes('w-32').on(
           'update:model-value', lambda e: update_fig(), throttle=1.0)
 
@@ -284,6 +285,7 @@ def index():
   ELM['switch_timer'].bind_value_to(ELM['timer'], 'active')
 
 def main_gui(args):
+  ELM['filedir'] = args.dir
   ui.run(
     host=args.host, port=int(args.port), title=ELM['name'],
     dark=False,