diff --git a/src/simulation/elements/HEAC.cpp b/src/simulation/elements/HEAC.cpp
index b16d6e9b2..9bdeba37d 100644
--- a/src/simulation/elements/HEAC.cpp
+++ b/src/simulation/elements/HEAC.cpp
@@ -1,3 +1,5 @@
+#include <algorithm>
+#include <functional>
 #include "simulation/Elements.h"
 #include "simulation/Air.h"
 //#TPT-Directive ElementClass Element_HEAC PT_HEAC 180
@@ -46,6 +48,79 @@ Element_HEAC::Element_HEAC()
 	Update = &Element_HEAC::update;
 }
 
+//#TPT-Directive ElementHeader Element_HEAC struct IsInsulator
+struct Element_HEAC::IsInsulator : public std::binary_function<Simulation*,int,bool> {
+  bool operator() (Simulation* a, int b) {return b && a->elements[b].HeatConduct == 0;}
+};
+//#TPT-Directive ElementHeader Element_HEAC static IsInsulator isInsulator
+Element_HEAC::IsInsulator Element_HEAC::isInsulator = Element_HEAC::IsInsulator();
+
+// If this is used elsewhere (GOLD), it should be moved into Simulation.h
+//#TPT-Directive ElementHeader Element_HEAC template<class BinaryPredicate> static bool CheckLine(Simulation* sim, int x1, int y1, int x2, int y2, BinaryPredicate func)
+template<class BinaryPredicate>
+bool Element_HEAC::CheckLine(Simulation* sim, int x1, int y1, int x2, int y2, BinaryPredicate func)
+{
+	bool reverseXY = abs(y2-y1) > abs(x2-x1);
+	int x, y, dx, dy, sy;
+	float e, de;
+	if (reverseXY)
+	{
+		y = x1;
+		x1 = y1;
+		y1 = y;
+		y = x2;
+		x2 = y2;
+		y2 = y;
+	}
+	if (x1 > x2)
+	{
+		y = x1;
+		x1 = x2;
+		x2 = y;
+		y = y1;
+		y1 = y2;
+		y2 = y;
+	}
+	dx = x2 - x1;
+	dy = abs(y2 - y1);
+	e = 0.0f;
+	if (dx)
+		de = dy/(float)dx;
+	else
+		de = 0.0f;
+	y = y1;
+	sy = (y1<y2) ? 1 : -1;
+	for (x=x1; x<=x2; x++)
+	{
+		if (reverseXY)
+		{
+			if (func(sim, sim->pmap[x][y]&0xFF)) return true;
+		}
+		else
+		{
+			if (func(sim, sim->pmap[y][x]&0xFF)) return true;
+		}
+		e += de;
+		if (e >= 0.5f)
+		{
+			y += sy;
+			if ((y1<y2) ? (y<=y2) : (y>=y2))
+			{
+				if (reverseXY)
+				{
+					if (func(sim, sim->pmap[x][y]&0xFF)) return true;
+				}
+				else
+				{
+					if (func(sim, sim->pmap[y][x]&0xFF)) return true;
+				}
+			}
+			e -= 1.0f;
+		}
+	}
+	return false;
+}
+
 //#TPT-Directive ElementHeader Element_HEAC static int update(UPDATE_FUNC_ARGS)
 int Element_HEAC::update(UPDATE_FUNC_ARGS)
 {
@@ -58,7 +133,7 @@ int Element_HEAC::update(UPDATE_FUNC_ARGS)
 		{
 			rry = ry * rad;
 			rrx = rx * rad;
-			if (x+rrx >= 0 && x+rrx < XRES && y+rry >= 0 && y+rry < YRES)
+			if (x+rrx >= 0 && x+rrx < XRES && y+rry >= 0 && y+rry < YRES && !Element_HEAC::CheckLine<Element_HEAC::IsInsulator>(sim, x, y, x+rrx, y+rry, isInsulator))
 			{
 				r = pmap[y+rry][x+rrx];
 				if (r && sim->elements[r&0xFF].HeatConduct > 0)
@@ -86,7 +161,7 @@ int Element_HEAC::update(UPDATE_FUNC_ARGS)
 			{
 				rry = ry * rad;
 				rrx = rx * rad;
-				if (x+rrx >= 0 && x+rrx < XRES && y+rry >= 0 && y+rry < YRES)
+				if (x+rrx >= 0 && x+rrx < XRES && y+rry >= 0 && y+rry < YRES && !Element_HEAC::CheckLine<Element_HEAC::IsInsulator>(sim, x, y, x+rrx, y+rry, isInsulator))
 				{
 					r = pmap[y+rry][x+rrx];
 					if (r && sim->elements[r&0xFF].HeatConduct > 0)