diff --git a/py/hexagram/thermo.py b/py/hexagram/thermo.py
index f7429cb..aefba1d 100644
--- a/py/hexagram/thermo.py
+++ b/py/hexagram/thermo.py
@@ -59,7 +59,7 @@ class ThermoGauge(Dial):
         self.draw_value(cr, 0.78,  0, "C", 0, 5)
 
         cr.set_source_rgb(1, 0, 0)
-        self.draw_value(cr, 0.75, self.MAX_VALUE - self.MIN_VALUE, "H", -5, 5)
+        self.draw_value(cr, 0.75, self.MAX_VALUE - self.MIN_VALUE, "H", -20, 10)
 
         cr.set_line_width(6.0)