diff --git a/components/actor/hendiCtrl.py b/components/actor/hendiCtrl.py
index b8af436..0fa175f 100755
--- a/components/actor/hendiCtrl.py
+++ b/components/actor/hendiCtrl.py
@@ -9,7 +9,6 @@ from contextlib import contextmanager
 class HendiException(Exception):
 	pass
 
-class HendiCtrl:
 class HendiCtrl:
 	def __init__(self, port, speed):
 		self.ser = serial.Serial(port, speed)
diff --git a/utils/replay_sim.py b/utils/replay_sim.py
index 566d53f..8c713cf 100644
--- a/utils/replay_sim.py
+++ b/utils/replay_sim.py
@@ -69,7 +69,7 @@ def _infer_heatrate_soll_set(samples):
     return max(candidates, default=1.0) or 1.0
 
 
-def run_replay(samples, pid_params, heatrate_soll_set, plant_params, ambient, max_power, dt):
+def run_replay(samples, pid_params, heatrate_soll_set, plant_params, ambient, max_power, heater_efficiency, dt):
     """Closed-loop simulation: controller drives plant, plant feeds temp back.
 
     The plant is seeded at the real starting temperature from the log so the
@@ -94,7 +94,7 @@ def run_replay(samples, pid_params, heatrate_soll_set, plant_params, ambient, ma
         tc.set_heatrate_soll(heatrate_soll_set)
         tc.process()
 
-        power_watts = max(0.0, tc.get_power() * max_power)
+        power_watts = max(0.0, tc.get_power() * max_power * heater_efficiency)
         plant.set_power(power_watts)
 
         out.append({
@@ -186,6 +186,8 @@ def main():
                         help='Heat loss coefficient [W/(kg·K)] (default: %(default)s)')
     parser.add_argument('--plant-Td', type=float, default=30.0,  metavar='s',
                         help='Transport delay [s] (default: %(default)s)')
+    parser.add_argument('--heater-efficiency', type=float, default=1.0, metavar='0-1',
+                        help='Fraction of rated heater power delivered to the plant (default: %(default)s)')
 
     for section, prefix in (('Hold', 'hold'), ('Heat', 'heat'), ('Cool', 'cool')):
         for gain in ('kp', 'ki', 'kd', 'kt'):
@@ -234,15 +236,15 @@ def main():
     print('Log:    {} ({} samples, dt={:.1f} s)'.format(name, len(samples), dt))
     print('Power:  max={:.0f} W'.format(max_power))
     print('Rate:   heatrate_soll_set={:.2f} K/min'.format(rate_soll))
-    print('Plant:  M={M} kg  C={C} J/kgK  L={L} W/kgK  Td={Td} s  ambient={amb} °C'.format(
-        amb=ambient, **plant_params))
+    print('Plant:  M={M} kg  C={C} J/kgK  L={L} W/kgK  Td={Td} s  ambient={amb} °C  heater_efficiency={eff}'.format(
+        amb=ambient, eff=args.heater_efficiency, **plant_params))
     print('Params: {}'.format('overridden' if any_override else 'from config'))
     print()
     for section in ('Hold', 'Heat', 'Cool'):
         p = pid_params[section]
         print('  {}: kp={kp}  ki={ki}  kd={kd}  kt={kt}'.format(section, **p))
 
-    replay = run_replay(samples, pid_params, rate_soll, plant_params, ambient, max_power, dt)
+    replay = run_replay(samples, pid_params, rate_soll, plant_params, ambient, max_power, args.heater_efficiency, dt)
     plot_replay(samples, replay, name, max_power, params_label)
     plt.show()