diff --git a/client/brewpi_gui.py b/client/brewpi_gui.py
index 0995e7e..4cb15fb 100755
--- a/client/brewpi_gui.py
+++ b/client/brewpi_gui.py
@@ -722,6 +722,9 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 			self.sud_state = None
 			self.sud_user_message = None
 			self._close_confirm_dialog()
+			for w in (self.Slider_temp_soll, self.doubleSpinBox_heatrate_soll,
+					  self.Slider_pwr_soll, self.Slider_speed_soll):
+				w.setEnabled(True)
 			# ambient_temp (the server's last echoed reading, shown in the
 			# status bar) is no longer trustworthy, but the spinbox itself is
 			# a client-owned setting (see closeEvent()/connect()) - leave it
@@ -912,16 +915,13 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 				if 'Temp' in submsg:
 					self.plot_temp_soll = submsg['Temp']
 					self.lcdNumber_temp_soll.display(f'{submsg["Temp"]:.1f}')
-					if self.slider_temp_soll_initial_update:
-						# blockSignals: setValue() here is just syncing the
-						# slider's display to the server's current value, not
-						# a user edit - without this it would also fire
-						# valueChanged and echo the value straight back as a
-						# command.
+					sud_running = self.sud_state in SUD_RUNNING_STATES
+					if self.slider_temp_soll_initial_update or sud_running:
 						self.Slider_temp_soll.blockSignals(True)
 						self.Slider_temp_soll.setValue(int(round(submsg['Temp'])))
 						self.Slider_temp_soll.blockSignals(False)
-						self.slider_temp_soll_initial_update = False
+						if not sud_running:
+							self.slider_temp_soll_initial_update = False
 				if 'Rate' in submsg:
 					subsubmsg = submsg['Rate']
 					for subkey in subsubmsg:
@@ -929,11 +929,13 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 							self.plot_rate_soll = subsubmsg['Current']
 							self.lcdNumber_heatrate_soll.display(f'{subsubmsg["Current"]:.1f}')
 						if "Set" in subkey:
-							if self.heatrate_soll_initial_update:
-								self.heatrate_soll_initial_update = False
+							sud_running = self.sud_state in SUD_RUNNING_STATES
+							if self.heatrate_soll_initial_update or sud_running:
 								self.doubleSpinBox_heatrate_soll.blockSignals(True)
 								self.doubleSpinBox_heatrate_soll.setValue(subsubmsg['Set'])
 								self.doubleSpinBox_heatrate_soll.blockSignals(False)
+								if not sud_running:
+									self.heatrate_soll_initial_update = False
 			if "Ist" in key:
 				submsg = msg['Ist']
 				if 'Temp' in submsg:
@@ -949,6 +951,10 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 			if "PowerSet" in key:
 				self.plot_power_set = msg['PowerSet']
 				self.lcdNumber_power_heater.display(msg['PowerSet'])
+				if self.sud_state in SUD_RUNNING_STATES:
+					self.Slider_pwr_soll.blockSignals(True)
+					self.Slider_pwr_soll.setValue(int(round(msg['PowerSet'])))
+					self.Slider_pwr_soll.blockSignals(False)
 			elif "Power" in key:
 				self.plot_power_eff = msg['Power']
 				self.lcdNumber_power_pot.display(msg['Power'])
@@ -977,11 +983,13 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 			if "Speed" in key:
 				self.stirrer_speed_ist = msg['Speed']
 				self._update_step_plates()
-				if self.slider_speed_initial_update:
+				sud_running = self.sud_state in SUD_RUNNING_STATES
+				if self.slider_speed_initial_update or sud_running:
 					self.Slider_speed_soll.blockSignals(True)
 					self.Slider_speed_soll.setValue(int(round(msg['Speed'])))
 					self.Slider_speed_soll.blockSignals(False)
-					self.slider_speed_initial_update = False
+					if not sud_running:
+						self.slider_speed_initial_update = False
 			elif "Capabilities" in key:
 				submsg = msg['Capabilities']
 				if "Power" in submsg:
@@ -1008,6 +1016,10 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 			elif "State" in key:
 				prev_state = self.sud_state
 				self.sud_state = msg['State']
+				running = self.sud_state in SUD_RUNNING_STATES
+				for w in (self.Slider_temp_soll, self.doubleSpinBox_heatrate_soll,
+						  self.Slider_pwr_soll, self.Slider_speed_soll):
+					w.setEnabled(not running)
 
 				if self.sud_state in SUD_RUNNING_STATES and self.sud_elapsed_seconds is None:
 					self.sud_elapsed_seconds = 0.0
diff --git a/web/app.js b/web/app.js
index 72ccce5..569bb14 100644
--- a/web/app.js
+++ b/web/app.js
@@ -526,6 +526,10 @@ function onHeaterChanged(msg) {
 			heaterPowerSoll = msg.PowerSet;
 			document.getElementById('lcd-power-soll').textContent = msg.PowerSet;
 			updateFireVisualization();
+			if (RUNNING_STATES.has(sudState)) {
+				document.getElementById('heater-power').value = msg.PowerSet;
+				document.getElementById('heater-power-readout').textContent = msg.PowerSet;
+			}
 		} else if (key === 'Power') {
 			heaterPowerIst = msg.Power;
 			document.getElementById('lcd-power-ist').textContent = msg.Power;
@@ -548,10 +552,11 @@ function onStirrerChanged(msg) {
 	for (const key of Object.keys(msg)) {
 		if (key === 'Speed') {
 			stirrerSpeedIst = msg.Speed;
-			if (initialSpeedSync) {
+			const sudRunningSpd = RUNNING_STATES.has(sudState);
+			if (initialSpeedSync || sudRunningSpd) {
 				document.getElementById('stirrer-speed').value = msg.Speed;
 				document.getElementById('stirrer-speed-readout').textContent = msg.Speed;
-				initialSpeedSync = false;
+				if (!sudRunningSpd) initialSpeedSync = false;
 			}
 			updateStirrerVisualization();
 			updateStepPlates();
@@ -571,9 +576,10 @@ function onTempCtrlChanged(msg) {
 			if ('Temp' in soll) {
 				plotTempSoll = soll.Temp;
 				document.getElementById('lcd-temp-soll').textContent = soll.Temp.toFixed(1);
-				if (initialTempSollSync) {
+				const sudRunning = RUNNING_STATES.has(sudState);
+				if (initialTempSollSync || sudRunning) {
 					document.getElementById('temp-soll').value = Math.round(soll.Temp);
-					initialTempSollSync = false;
+					if (!sudRunning) initialTempSollSync = false;
 				}
 				document.getElementById('temp-soll-readout').textContent = document.getElementById('temp-soll').value;
 				updatePotVisualization();
@@ -583,9 +589,10 @@ function onTempCtrlChanged(msg) {
 				if ('Current' in rate) {
 					document.getElementById('lcd-rate-soll').textContent = rate.Current.toFixed(1);
 				}
-				if ('Set' in rate && initialHeatrateSync) {
+				const sudRunningHr = RUNNING_STATES.has(sudState);
+				if ('Set' in rate && (initialHeatrateSync || sudRunningHr)) {
 					document.getElementById('heatrate-soll').value = rate.Set;
-					initialHeatrateSync = false;
+					if (!sudRunningHr) initialHeatrateSync = false;
 				}
 			}
 		}
@@ -635,6 +642,10 @@ function onSudChanged(msg) {
 			}
 			wasRunning = isRunningNow;
 			sudState = newState;
+			const sliderDisabled = RUNNING_STATES.has(sudState);
+			for (const id of ['temp-soll', 'heatrate-soll', 'heater-power', 'stirrer-speed']) {
+				document.getElementById(id).disabled = sliderDisabled;
+			}
 			if (newState === WAIT_USER_STATE && prevState !== WAIT_USER_STATE && sudUserMessage) {
 				showUserMessage(sudUserMessage);
 			} else if (prevState === WAIT_USER_STATE && newState !== WAIT_USER_STATE) {
@@ -740,6 +751,10 @@ function connect() {
 	ws = ws_;
 	statusEl.textContent = 'Connecting…';
 	ws.onopen = () => {
+		initialPowerSync = true;
+		initialSpeedSync = true;
+		initialHeatrateSync = true;
+		initialTempSollSync = true;
 		setConnected(true);
 		for (const channel of CHANNELS) {
 			ws.send(JSON.stringify({'+': channel}));
@@ -754,7 +769,12 @@ function connect() {
 		statusEl.textContent = `Could not connect to ${url}`;
 		statusEl.className = 'status-disconnected';
 	};
-	ws.onclose = () => setConnected(false);
+	ws.onclose = () => {
+		for (const id of ['temp-soll', 'heatrate-soll', 'heater-power', 'stirrer-speed']) {
+			document.getElementById(id).disabled = false;
+		}
+		setConnected(false);
+	};
 	ws.onmessage = (event) => {
 		const msg = JSON.parse(event.data);
 		for (const channel of Object.keys(msg)) {