diff --git a/restoration/source410/BT/HEAT.CPP b/restoration/source410/BT/HEAT.CPP
index 2a361ff7..48af947d 100644
--- a/restoration/source410/BT/HEAT.CPP
+++ b/restoration/source410/BT/HEAT.CPP
@@ -946,3 +946,138 @@ void
 		DEBUG_STREAM << flush;
 	}
 }
+
+//###########################################################################
+//#########################   AggregateHeatSink   ###########################
+//###########################################################################
+
+Derivation
+	AggregateHeatSink::ClassDerivations(
+		HeatSink::ClassDerivations,
+		"HeatSinkBank"
+	);
+
+AggregateHeatSink::SharedData
+	AggregateHeatSink::DefaultData(
+		AggregateHeatSink::ClassDerivations,
+		HeatSink::MessageHandlers,
+		Subsystem::AttributeIndex,
+		Subsystem::StateCount
+	);
+
+//
+//#############################################################################
+// The heat-sink bank (binary ctor @4ae8d0): the aggregate count scales the
+// conductance (0.1 x count, byte-verified), the ambient setpoint defaults
+// 300 K (the mission's [mission] temperature overwrites it in the PlayerLink
+// pass -- that override joins the Mech-PlayerLink wave), and a master runs
+// the RADIATOR Performance instead of the base heat step.
+//#############################################################################
+//
+AggregateHeatSink::AggregateHeatSink(
+	Mech				*owner,
+	int					subsystem_ID,
+	SubsystemResource	*subsystem_resource,
+	SharedData			&shared_data
+):
+	HeatSink(owner, subsystem_ID, subsystem_resource, shared_data)
+{
+	Check(owner);
+	Check_Pointer(subsystem_resource);
+
+	heatSinkCount		= subsystem_resource->heatSinkCount;
+	ambientTemperature	= 300.0f;
+
+	thermalConductance = 0.1f * (Scalar)heatSinkCount * thermalConductance;
+
+	if (getenv("BT_POWER_LOG"))
+	{
+		DEBUG_STREAM << "[bank] '" << GetName()
+			<< "' heatSinkCount=" << heatSinkCount
+			<< " conductance=" << thermalConductance << endl << flush;
+	}
+
+	if (owner->GetInstance() != Entity::ReplicantInstance)
+	{
+		SetPerformance(&AggregateHeatSink::RadiatorSimulation);
+	}
+
+	Check_Fpu();
+}
+
+AggregateHeatSink::~AggregateHeatSink()
+{
+}
+
+Logical
+	AggregateHeatSink::TestClass(Mech &)
+{
+	return True;
+}
+
+Logical
+	AggregateHeatSink::TestInstance() const
+{
+	return IsDerivedFrom(ClassDerivations);
+}
+
+//
+//#############################################################################
+// RadiatorSimulation -- the bank's per-frame step (binary @4ae73c), replacing
+// the base HeatSinkSimulation: under the heat-model gate, absorb + recompute
+// the load, then the AMBIENT RADIATOR -- relax the bank toward the setpoint
+// target (300 - (300 - ambient) x 3) with rate k = conductance x (1 - own
+// damage) x (coolant/capacity) x flowScale / mass.  This is the system's ONLY
+// heat exit.  Tail: top the bank's coolant up from the attached store via the
+// DrawCoolant virtual (the reservoir-attach routing joins that wave; the base
+// supplies 0 until then, a harmless no-op).
+//#############################################################################
+//
+void
+	AggregateHeatSink::RadiatorSimulation(Scalar time_slice)
+{
+	Check(this);
+
+	if (HeatModelActive())
+	{
+		heatEnergy         += pendingHeat;
+		currentTemperature  = heatEnergy / thermalMass;
+		UpdateHeatLoad();
+		pendingHeat         = 0.0f;
+
+		Scalar target = 300.0f - (300.0f - ambientTemperature) * 3.0f;
+		Scalar decay = 1.0f - (Scalar)exp(
+			(double)(-(time_slice * thermalConductance
+				* (1.0f - GetSubsystemDamageLevel())
+				* (coolantLevel / thermalCapacity) * coolantFlowScale)
+				/ thermalMass)
+		);
+		Scalar shed = -((currentTemperature * massScale - target)
+			* thermalMass * decay);
+		pendingHeat += shed;
+
+		if (getenv("BT_HEAT_LOG"))
+		{
+			static Scalar bankAccum = 0.0f;
+			bankAccum += time_slice;
+			if (bankAccum >= 5.0f)
+			{
+				bankAccum = 0.0f;
+				DEBUG_STREAM << "[heat-t] " << GetName() << " (bank)"
+					<< " T=" << currentTemperature
+					<< " shed=" << shed
+					<< " cool=" << coolantLevel << "/" << thermalCapacity
+					<< " load=" << heatLoad << endl << flush;
+			}
+		}
+	}
+
+	//
+	// Coolant top-up from the attached store.
+	//
+	Scalar deficit = thermalCapacity - coolantLevel;
+	if (deficit > 1.0e-4f)
+	{
+		coolantLevel += DrawCoolant(deficit);
+	}
+}
diff --git a/restoration/source410/BT/HEAT.HPP b/restoration/source410/BT/HEAT.HPP
index fb61bcb5..f01e0c7f 100644
--- a/restoration/source410/BT/HEAT.HPP
+++ b/restoration/source410/BT/HEAT.HPP
@@ -423,4 +423,71 @@
 		Scalar	refrigerationFactor;
 	};
 
+//###########################################################################
+//#####################   AggregateHeatSink Resource   ######################
+//###########################################################################
+
+	struct AggregateHeatSink__SubsystemResource:
+		public HeatSink__SubsystemResource
+	{
+		int		heatSinkCount;
+	};
+
+//###########################################################################
+//#########################   AggregateHeatSink   ###########################
+//###########################################################################
+//
+// The mech's heat-sink BANK (binary classID 0x0BBE -- the value our VDATA
+// enum names HeatSinkClassID; there is no streamed plain-HeatSink class).
+// Holds the aggregate heat-sink count and the ambient-temperature setpoint,
+// and runs the AMBIENT RADIATOR -- the only place heat ever LEAVES the mech.
+//
+	class AggregateHeatSink:
+		public HeatSink
+	{
+	public:
+		static Derivation ClassDerivations;
+		static SharedData DefaultData;
+
+		static Logical
+			TestClass(Mech &);
+		Logical
+			TestInstance() const;
+
+	public:
+		typedef AggregateHeatSink__SubsystemResource SubsystemResource;
+
+		AggregateHeatSink(
+			Mech						*owner,
+			int							subsystem_ID,
+			SubsystemResource			*subsystem_resource,
+			SharedData					&shared_data = DefaultData
+		);
+		~AggregateHeatSink();
+
+	//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+	// The radiator (binary @4ae73c) -- replaces the base HeatSinkSimulation on
+	// the bank: absorb, then relax toward the ambient setpoint (the heat EXIT),
+	// then top the bank's coolant up from the attached store.
+	//
+	public:
+		typedef void
+			(AggregateHeatSink::*Performance)(Scalar time_slice);
+		void
+			SetPerformance(Performance performance)
+				{
+					Check(this);
+					activePerformance = (Simulation::Performance)performance;
+				}
+		void
+			RadiatorSimulation(Scalar time_slice);
+
+		int
+			GetHeatSinkCount() const	{ Check(this); return heatSinkCount; }
+
+	protected:
+		int		heatSinkCount;
+		Scalar	ambientTemperature;
+	};
+
 #endif
diff --git a/restoration/source410/BT/HEAT.NOTES.md b/restoration/source410/BT/HEAT.NOTES.md
index 820c49ee..74aaf105 100644
--- a/restoration/source410/BT/HEAT.NOTES.md
+++ b/restoration/source410/BT/HEAT.NOTES.md
@@ -200,3 +200,26 @@ VERIFIED: spawn shares 6 x 0.166667; one MoveValve press -> Condenser1
 valve=5 flow=0.5, the others 0.1 (valve/sum exactly); the flush arms via the
 real button message; NOVICE: both presses swallowed by the lockout (valve
 lines stay spawn-only, zero flush).  Zero Fail throughout.
+
+## The heat-sink BANK (Phase 5.3.14, 2026-07-24)
+
+**AggregateHeatSink reconstructed** -- the binary's 0x0BBE class (the value our
+VDATA enum names HeatSinkClassID; there is NO streamed plain-HeatSink -- the
+walk now builds the bank).  Ctor (@4ae8d0): heatSinkCount from res +0xFC
+(bhk1 = 6, matching its six condensers), thermalConductance x 0.1 x count
+(231000 -> 138600), ambient setpoint 300 (the mission-temperature overwrite
+joins the Mech-PlayerLink wave).
+
+**RadiatorSimulation** (@4ae73c) replaces the base heat step on the bank --
+THE system's only heat exit: relax toward the ambient target with rate
+k = conductance x (1 - damage) x (coolant/capacity) x flowScale / mass, then
+top the bank's coolant from the attached store via the DrawCoolant virtual
+(base 0 until the reservoir attach wave).  VERIFIED signed-correct: the bank
+warms 77 -> 300 from the cold start (shed positive, absorbing toward
+ambient), then flips negative (-48K.. -167K/step) as fired heat pushes it
+past ambient -- actively radiating the mech's heat away.
+
+**Reservoir master rescale**: capacity = 0.05 x bankCount x streamed
+(0.05 x 6 x 20 = 6 -- the authentic tank), coolant refilled to it.
+
+Zero Fail; the full expert economy regression stays green.
diff --git a/restoration/source410/BT/MECH.CPP b/restoration/source410/BT/MECH.CPP
index f4c3efcb..e873228a 100644
--- a/restoration/source410/BT/MECH.CPP
+++ b/restoration/source410/BT/MECH.CPP
@@ -239,7 +239,12 @@ Mech::Mech(
 			made = new Condenser(this, id, (Condenser::SubsystemResource *)seg);
 			break;
 		case HeatSinkClassID:
-			made = new HeatSink(this, id, (HeatSink::SubsystemResource *)seg);
+			//
+			// The 0x0BBE stream class is the mech's heat-sink BANK
+			// (AggregateHeatSink) -- there is no streamed plain-HeatSink; our
+			// VDATA enum name simply predates that discovery.
+			//
+			made = new AggregateHeatSink(this, id, (AggregateHeatSink::SubsystemResource *)seg);
 			break;
 		case HeatWatcherClassID:
 			made = new HeatWatcher(this, id, (HeatWatcher::SubsystemResource *)seg);
diff --git a/restoration/source410/BT/RESERVR.CPP b/restoration/source410/BT/RESERVR.CPP
index c78fa6c3..8cea36c8 100644
--- a/restoration/source410/BT/RESERVR.CPP
+++ b/restoration/source410/BT/RESERVR.CPP
@@ -101,6 +101,28 @@ Reservoir::Reservoir(
 	if (owner->GetInstance() != Entity::ReplicantInstance)
 	{
 		SetPerformance(&Reservoir::CoolantSimulation);
+
+		//
+		// The authentic master path scales the tank by the bank's aggregate
+		// heat-sink count: capacity = 0.05 x count x streamed (binary
+		// @4af408, CoolantCapacityScale byte-verified 0.05).  The linked sink
+		// (from the resource) IS the bank.  (The bank-side Attach that routes
+		// its DrawCoolant top-ups here joins the attach wave.)
+		//
+		HeatSink *link = (HeatSink *)linkedSinks.Resolve();
+		if (link != NULL
+			&& link->IsDerivedFrom(AggregateHeatSink::ClassDerivations))
+		{
+			Scalar masterScale =
+				(Scalar)((AggregateHeatSink *)link)->GetHeatSinkCount();
+			thermalCapacity = 0.05f * masterScale * thermalCapacity;
+			coolantLevel    = thermalCapacity;
+			if (getenv("BT_POWER_LOG"))
+			{
+				DEBUG_STREAM << "[resv] capacity rescaled by bank count -> "
+					<< thermalCapacity << endl << flush;
+			}
+		}
 	}
 
 	Check_Fpu();