diff --git a/actuators.py b/actuators.py
index 982d93e..5dd3aab 100644
--- a/actuators.py
+++ b/actuators.py
@@ -30,7 +30,6 @@ class GPIOPin(Actuator):
 
     def enable(self, enable=True):
         GPIO.output(self.pin, self.onstate) if enable else self.disable()
-       
 
     def disable(self):
         GPIO.output(self.pin, self.offstate)
diff --git a/phasectrl.py b/phasectrl.py
index 36ec145..d869e00 100644
--- a/phasectrl.py
+++ b/phasectrl.py
@@ -175,7 +175,7 @@ class State():
         return None
 
     def phase_time(self, arg=None):
-        return (self.now() - self.envdata['current-phase-loadtime'])
+        return (self.now() - self.envdata.get('current-phase-loadtime', 0))
 
     def loadphase(self, phaseidx):
         phase = self.recipe.phases[phaseidx]
diff --git a/sensors.py b/sensors.py
index e70ef97..77f9320 100644
--- a/sensors.py
+++ b/sensors.py
@@ -4,6 +4,9 @@ from collections import deque
 import re
 from os.path import exists
 
+import RPi.GPIO as GPIO
+GPIO.setmode(GPIO.BCM)
+
 # TODO client: add a way to disable live plotting? server: stop
 # sending data periodically to everybody!
 
@@ -21,6 +24,14 @@ class Sensor():
         return (perf_counter(),
                 int((random() * (1-self.auto) + self.prevval * self.auto) * 100) / 100)
 
+class GPIOState(Sensor):
+    def __init__(self, pin, transform=lambda x: 1-x):
+        self.pin = pin
+        self.transform = transform
+
+    def read(self):
+        return self.transform(GPIO.input(self.pin))
+
 class Temperature1W(Sensor):
     def __init__(self, address):
         self.measure = 'Temperature'
@@ -61,6 +72,7 @@ class Sensors():
         self.available_sensors = {
             'T_ext': Temperature1W('28-06214252b671'),
             'T_food': Temperature1W('28-062142531e5a'),
+            'heater': GPIOState(22),
         }
 
     def list(self):