diff --git a/src/foam/Make/files b/src/foam/Make/files
index d506e7a3f..f0f928e7d 100644
--- a/src/foam/Make/files
+++ b/src/foam/Make/files
@@ -141,6 +141,7 @@ $(StringStreams)/StringStreamsPrint.C
 
 Pstreams = $(Streams)/Pstreams
 $(Pstreams)/Pstream.C
+$(Pstreams)/PstreamReduceOps.C
 $(Pstreams)/PstreamCommsStruct.C
 $(Pstreams)/PstreamGlobals.C
 $(Pstreams)/IPstream.C
diff --git a/src/foam/db/IOstreams/Pstreams/Pstream.C b/src/foam/db/IOstreams/Pstreams/Pstream.C
index e87e9836d..cb78615d0 100644
--- a/src/foam/db/IOstreams/Pstreams/Pstream.C
+++ b/src/foam/db/IOstreams/Pstreams/Pstream.C
@@ -32,21 +32,11 @@ License
 #include "OSspecific.H"
 #include "PstreamGlobals.H"
 #include "SubList.H"
-#include "allReduce.H"
 
 #include <cstring>
 #include <cstdlib>
 #include <csignal>
 
-#if defined(WM_SP)
-#   define MPI_SCALAR MPI_FLOAT
-#elif defined(WM_DP)
-#   define MPI_SCALAR MPI_DOUBLE
-#elif defined(WM_LDP)
-#   define MPI_SCALAR MPI_LONG_DOUBLE
-#endif
-
-
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
 defineTypeNameAndDebug(Foam::Pstream, 0);
@@ -548,8 +538,6 @@ Foam::label Foam::Pstream::procNo
 }
 
 
-
-
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 
@@ -680,230 +668,6 @@ void Foam::Pstream::abort()
 }
 
 
-void Foam::reduce
-(
-    bool& Value,
-    const andOp<bool>& bop,
-    const int tag,
-    const label comm
-)
-{
-    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
-    {
-        Pout<< "** reducing:" << Value << " with comm:" << comm
-            << " warnComm:" << Pstream::warnComm
-            << endl;
-        error::printStack(Pout);
-    }
-
-    // Note: C++ bool is a type separate from C and cannot be cast
-    // For safety and compatibility with compilers, convert bool to int
-    // to comply with MPI types.  HJ, 23/Sep/2016
-
-    int intBool = 0;
-
-    if (Value)
-    {
-        intBool = 1;
-    }
-
-    allReduce(intBool, 1, MPI_INT, MPI_LAND, bop, tag, comm);
-
-    if (intBool > 0)
-    {
-        Value = true;
-    }
-    else
-    {
-        Value = false;
-    }
-}
-
-
-void Foam::reduce
-(
-    bool& Value,
-    const orOp<bool>& bop,
-    const int tag,
-    const label comm
-)
-{
-    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
-    {
-        Pout<< "** reducing:" << Value << " with comm:" << comm
-            << " warnComm:" << Pstream::warnComm
-            << endl;
-        error::printStack(Pout);
-    }
-
-    // Note: C++ bool is a type separate from C and cannot be cast
-    // For safety and compatibility with compilers, convert bool to int
-    // to comply with MPI types.  HJ, 23/Sep/2016
-
-    int intBool = 0;
-
-    if (Value)
-    {
-        intBool = 1;
-    }
-
-    allReduce(intBool, 1, MPI_INT, MPI_LOR, bop, tag, comm);
-
-    if (intBool > 0)
-    {
-        Value = true;
-    }
-    else
-    {
-        Value = false;
-    }
-}
-
-
-void Foam::reduce
-(
-    scalar& Value,
-    const minOp<scalar>& bop,
-    const int tag,
-    const label comm
-)
-{
-    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
-    {
-        Pout<< "** reducing:" << Value << " with comm:" << comm
-            << " warnComm:" << Pstream::warnComm
-            << endl;
-        error::printStack(Pout);
-    }
-    allReduce(Value, 1, MPI_SCALAR, MPI_MIN, bop, tag, comm);
-}
-
-
-void Foam::reduce
-(
-    scalar& Value,
-    const maxOp<scalar>& bop,
-    const int tag,
-    const label comm
-)
-{
-    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
-    {
-        Pout<< "** reducing:" << Value << " with comm:" << comm
-            << " warnComm:" << Pstream::warnComm
-            << endl;
-        error::printStack(Pout);
-    }
-    allReduce(Value, 1, MPI_SCALAR, MPI_MAX, bop, tag, comm);
-}
-
-
-void Foam::reduce
-(
-    scalar& Value,
-    const sumOp<scalar>& bop,
-    const int tag,
-    const label comm
-)
-{
-    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
-    {
-        Pout<< "** reducing:" << Value << " with comm:" << comm
-            << " warnComm:" << Pstream::warnComm
-            << endl;
-        error::printStack(Pout);
-    }
-
-    allReduce(Value, 1, MPI_SCALAR, MPI_SUM, bop, tag, comm);
-}
-
-
-void Foam::reduce
-(
-    vector2D& Value,
-    const sumOp<vector2D>& bop,
-    const int tag,
-    const label comm
-)
-{
-    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
-    {
-        Pout<< "** reducing:" << Value << " with comm:" << comm
-            << " warnComm:" << Pstream::warnComm
-            << endl;
-        error::printStack(Pout);
-    }
-    allReduce(Value, 2, MPI_SCALAR, MPI_SUM, bop, tag, comm);
-}
-
-
-void Foam::sumReduce
-(
-    scalar& Value,
-    label& Count,
-    const int tag,
-    const label comm
-)
-{
-    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
-    {
-        Pout<< "** reducing:" << Value << " with comm:" << comm
-            << " warnComm:" << Pstream::warnComm
-            << endl;
-        error::printStack(Pout);
-    }
-    vector2D twoScalars(Value, scalar(Count));
-    reduce(twoScalars, sumOp<vector2D>(), tag, comm);
-
-    Value = twoScalars.x();
-    Count = twoScalars.y();
-}
-
-
-void Foam::reduce
-(
-    scalar& Value,
-    const sumOp<scalar>& bop,
-    const int tag,
-    const label comm,
-    label& requestID
-)
-{
-#ifdef MPIX_COMM_TYPE_SHARED
-    // Assume mpich2 with non-blocking collectives extensions. Once mpi3
-    // is available this will change.
-    MPI_Request request;
-    scalar v = Value;
-    MPIX_Ireduce
-    (
-        &v,
-        &Value,
-        1,
-        MPI_SCALAR,
-        MPI_SUM,
-        0,              // root
-        PstreamGlobals::MPICommunicators_[comm],
-        &request
-    );
-
-    requestID = PstreamGlobals::outstandingRequests_.size();
-    PstreamGlobals::outstandingRequests_.append(request);
-
-    if (debug)
-    {
-        Pout<< "Pstream::allocateRequest for non-blocking reduce"
-            << " : request:" << requestID
-            << endl;
-    }
-#else
-    // Non-blocking not yet implemented in mpi
-    reduce(Value, bop, tag, comm);
-
-    requestID = -1;
-#endif
-}
-
-
 Foam::label Foam::Pstream::nRequests()
 {
     return PstreamGlobals::outstandingRequests_.size();
diff --git a/src/foam/db/IOstreams/Pstreams/PstreamReduceOps.C b/src/foam/db/IOstreams/Pstreams/PstreamReduceOps.C
new file mode 100644
index 000000000..1ccf5ed27
--- /dev/null
+++ b/src/foam/db/IOstreams/Pstreams/PstreamReduceOps.C
@@ -0,0 +1,357 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | foam-extend: Open Source CFD
+   \\    /   O peration     | Version:     4.0
+    \\  /    A nd           | Web:         http://www.foam-extend.org
+     \\/     M anipulation  | For copyright notice see file Copyright
+-------------------------------------------------------------------------------
+License
+    This file is part of foam-extend.
+
+    foam-extend is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by the
+    Free Software Foundation, either version 3 of the License, or (at your
+    option) any later version.
+
+    foam-extend is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with foam-extend.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "mpi.h"
+
+#include "label.H"
+#include "Pstream.H"
+#include "PstreamReduceOps.H"
+#include "allReduce.H"
+
+// Check type of label for use in MPI calls
+#if defined(WM_INT)
+#   define MPI_LABEL MPI_INT
+#elif defined(WM_LONG)
+#   define MPI_LABEL MPI_LONG
+#elif defined(WM_LLONG)
+#   define MPI_LABEL MPI_LONG_LONG
+#endif
+
+// Check type of scalar for use in MPI calls
+#if defined(WM_SP)
+#   define MPI_SCALAR MPI_FLOAT
+#elif defined(WM_DP)
+#   define MPI_SCALAR MPI_DOUBLE
+#elif defined(WM_LDP)
+#   define MPI_SCALAR MPI_LONG_DOUBLE
+#endif
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+// Optimizing template specialisations using MPI_REDUCE
+void Foam::reduce
+(
+    bool& Value,
+    const andOp<bool>& bop,
+    const int tag,
+    const label comm
+)
+{
+    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
+    {
+        Pout<< "** reducing:" << Value << " with comm:" << comm
+            << " warnComm:" << Pstream::warnComm
+            << endl;
+        error::printStack(Pout);
+    }
+
+    // Note: C++ bool is a type separate from C and cannot be cast
+    // For safety and compatibility with compilers, convert bool to int
+    // to comply with MPI types.  HJ, 23/Sep/2016
+
+    int intBool = 0;
+
+    if (Value)
+    {
+        intBool = 1;
+    }
+
+    allReduce(intBool, 1, MPI_INT, MPI_LAND, bop, tag, comm);
+
+    if (intBool > 0)
+    {
+        Value = true;
+    }
+    else
+    {
+        Value = false;
+    }
+}
+
+
+void Foam::reduce
+(
+    bool& Value,
+    const orOp<bool>& bop,
+    const int tag,
+    const label comm
+)
+{
+    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
+    {
+        Pout<< "** reducing:" << Value << " with comm:" << comm
+            << " warnComm:" << Pstream::warnComm
+            << endl;
+        error::printStack(Pout);
+    }
+
+    // Note: C++ bool is a type separate from C and cannot be cast
+    // For safety and compatibility with compilers, convert bool to int
+    // to comply with MPI types.  HJ, 23/Sep/2016
+
+    int intBool = 0;
+
+    if (Value)
+    {
+        intBool = 1;
+    }
+
+    allReduce(intBool, 1, MPI_INT, MPI_LOR, bop, tag, comm);
+
+    if (intBool > 0)
+    {
+        Value = true;
+    }
+    else
+    {
+        Value = false;
+    }
+}
+
+
+void Foam::reduce
+(
+    label& Value,
+    const minOp<label>& bop,
+    const int tag,
+    const label comm
+)
+{
+    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
+    {
+        Pout<< "** reducing:" << Value << " with comm:" << comm
+            << " warnComm:" << Pstream::warnComm
+            << endl;
+        error::printStack(Pout);
+    }
+    allReduce(Value, 1, MPI_LABEL, MPI_MIN, bop, tag, comm);
+}
+
+
+void Foam::reduce
+(
+    label& Value,
+    const maxOp<label>& bop,
+    const int tag,
+    const label comm
+)
+{
+    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
+    {
+        Pout<< "** reducing:" << Value << " with comm:" << comm
+            << " warnComm:" << Pstream::warnComm
+            << endl;
+        error::printStack(Pout);
+    }
+    allReduce(Value, 1, MPI_LABEL, MPI_MAX, bop, tag, comm);
+}
+
+
+void Foam::reduce
+(
+    label& Value,
+    const sumOp<label>& bop,
+    const int tag,
+    const label comm
+)
+{
+    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
+    {
+        Pout<< "** reducing:" << Value << " with comm:" << comm
+            << " warnComm:" << Pstream::warnComm
+            << endl;
+        error::printStack(Pout);
+    }
+
+    allReduce(Value, 1, MPI_LABEL, MPI_SUM, bop, tag, comm);
+}
+
+
+void Foam::reduce
+(
+    scalar& Value,
+    const minOp<scalar>& bop,
+    const int tag,
+    const label comm
+)
+{
+    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
+    {
+        Pout<< "** reducing:" << Value << " with comm:" << comm
+            << " warnComm:" << Pstream::warnComm
+            << endl;
+        error::printStack(Pout);
+    }
+    allReduce(Value, 1, MPI_SCALAR, MPI_MIN, bop, tag, comm);
+}
+
+
+void Foam::reduce
+(
+    scalar& Value,
+    const maxOp<scalar>& bop,
+    const int tag,
+    const label comm
+)
+{
+    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
+    {
+        Pout<< "** reducing:" << Value << " with comm:" << comm
+            << " warnComm:" << Pstream::warnComm
+            << endl;
+        error::printStack(Pout);
+    }
+    allReduce(Value, 1, MPI_SCALAR, MPI_MAX, bop, tag, comm);
+}
+
+
+void Foam::reduce
+(
+    scalar& Value,
+    const sumOp<scalar>& bop,
+    const int tag,
+    const label comm
+)
+{
+    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
+    {
+        Pout<< "** reducing:" << Value << " with comm:" << comm
+            << " warnComm:" << Pstream::warnComm
+            << endl;
+        error::printStack(Pout);
+    }
+
+    allReduce(Value, 1, MPI_SCALAR, MPI_SUM, bop, tag, comm);
+}
+
+
+void Foam::reduce
+(
+    UList<label>& Value,
+    const sumOp<UList<label> >& bop,
+    const int tag,
+    const label comm
+)
+{
+    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
+    {
+        Pout<< "** reducing:" << Value << " with comm:" << comm
+            << " warnComm:" << Pstream::warnComm
+            << endl;
+        error::printStack(Pout);
+    }
+
+    allReduce(*Value.begin(), Value.size(), MPI_LABEL, MPI_SUM, bop, tag, comm);
+}
+
+
+void Foam::reduce
+(
+    vector2D& Value,
+    const sumOp<vector2D>& bop,
+    const int tag,
+    const label comm
+)
+{
+    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
+    {
+        Pout<< "** reducing:" << Value << " with comm:" << comm
+            << " warnComm:" << Pstream::warnComm
+            << endl;
+        error::printStack(Pout);
+    }
+    allReduce(Value, 2, MPI_SCALAR, MPI_SUM, bop, tag, comm);
+}
+
+
+void Foam::sumReduce
+(
+    scalar& Value,
+    label& Count,
+    const int tag,
+    const label comm
+)
+{
+    if (Pstream::warnComm != -1 && comm != Pstream::warnComm)
+    {
+        Pout<< "** reducing:" << Value << " with comm:" << comm
+            << " warnComm:" << Pstream::warnComm
+            << endl;
+        error::printStack(Pout);
+    }
+    vector2D twoScalars(Value, scalar(Count));
+    reduce(twoScalars, sumOp<vector2D>(), tag, comm);
+
+    Value = twoScalars.x();
+    Count = twoScalars.y();
+}
+
+
+void Foam::reduce
+(
+    scalar& Value,
+    const sumOp<scalar>& bop,
+    const int tag,
+    const label comm,
+    label& requestID
+)
+{
+#ifdef MPIX_COMM_TYPE_SHARED
+    // Assume mpich2 with non-blocking collectives extensions. Once mpi3
+    // is available this will change.
+    MPI_Request request;
+    scalar v = Value;
+    MPIX_Ireduce
+    (
+        &v,
+        &Value,
+        1,
+        MPI_SCALAR,
+        MPI_SUM,
+        0,              // root
+        PstreamGlobals::MPICommunicators_[comm],
+        &request
+    );
+
+    requestID = PstreamGlobals::outstandingRequests_.size();
+    PstreamGlobals::outstandingRequests_.append(request);
+
+    if (debug)
+    {
+        Pout<< "Pstream::allocateRequest for non-blocking reduce"
+            << " : request:" << requestID
+            << endl;
+    }
+#else
+    // Non-blocking not yet implemented in mpi
+    reduce(Value, bop, tag, comm);
+
+    requestID = -1;
+#endif
+}
+
+
+// ************************************************************************* //
diff --git a/src/foam/db/IOstreams/Pstreams/PstreamReduceOps.H b/src/foam/db/IOstreams/Pstreams/PstreamReduceOps.H
index 65970bf88..d81dc8487 100644
--- a/src/foam/db/IOstreams/Pstreams/PstreamReduceOps.H
+++ b/src/foam/db/IOstreams/Pstreams/PstreamReduceOps.H
@@ -159,6 +159,33 @@ void reduce
     const label comm = Pstream::worldComm
 );
 
+
+// Insist there are specialisations for the common reductions of labels
+
+void reduce
+(
+    label& Value,
+    const sumOp<label>& bop,
+    const int tag = Pstream::msgType(),
+    const label comm = Pstream::worldComm
+);
+
+void reduce
+(
+    label& Value,
+    const minOp<label>& bop,
+    const int tag = Pstream::msgType(),
+    const label comm = Pstream::worldComm
+);
+
+void reduce
+(
+    label& Value,
+    const maxOp<label>& bop,
+    const int tag = Pstream::msgType(),
+    const label comm = Pstream::worldComm
+);
+
 // Insist there are specialisations for the common reductions of scalars
 
 void reduce
@@ -211,6 +238,34 @@ void reduce
 );
 
 
+// Insist there are specialisations for the common reductions of
+// lists of labels
+
+void reduce
+(
+    UList<label>& Value,
+    const sumOp<UList<label> >& bop,
+    const int tag = Pstream::msgType(),
+    const label comm = Pstream::worldComm
+);
+
+void reduce
+(
+    UList<label>& Value,
+    const minOp<UList<label> >& bop,
+    const int tag = Pstream::msgType(),
+    const label comm = Pstream::worldComm
+);
+
+void reduce
+(
+    UList<label>& Value,
+    const maxOp<UList<label> >& bop,
+    const int tag = Pstream::msgType(),
+    const label comm = Pstream::worldComm
+);
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Foam
diff --git a/src/foam/db/IOstreams/Pstreams/allReduceTemplates.C b/src/foam/db/IOstreams/Pstreams/allReduceTemplates.C
index 13b6eddfc..89a2597e9 100644
--- a/src/foam/db/IOstreams/Pstreams/allReduceTemplates.C
+++ b/src/foam/db/IOstreams/Pstreams/allReduceTemplates.C
@@ -44,155 +44,155 @@ void Foam::allReduce
         return;
     }
 
-    if (Pstream::nProcs(comm) <= Pstream::nProcsSimpleSum)
-    {
-        if (Pstream::master(comm))
-        {
-            for
-            (
-                int slave = Pstream::firstSlave();
-                slave <= Pstream::lastSlave(comm);
-                slave++
-            )
-            {
-                Type value;
+//     if (Pstream::nProcs(comm) <= Pstream::nProcsSimpleSum)
+//     {
+//         if (Pstream::master(comm))
+//         {
+//             for
+//             (
+//                 int slave = Pstream::firstSlave();
+//                 slave <= Pstream::lastSlave(comm);
+//                 slave++
+//             )
+//             {
+//                 Type value;
 
-                if
-                (
-                    MPI_Recv
-                    (
-                        &value,
-                        MPICount,
-                        MPIType,
-                        slave,
-                        tag,
-                        PstreamGlobals::MPICommunicators_[comm],
-                        MPI_STATUS_IGNORE
-                    )
-                )
-                {
-                    FatalErrorIn
-                    (
-                        "void Foam::allReduce\n"
-                        "(\n"
-                        "    Type&,\n"
-                        "    int,\n"
-                        "    MPI_Datatype,\n"
-                        "    MPI_Op,\n"
-                        "    const BinaryOp&,\n"
-                        "    const int\n"
-                        ")\n"
-                    )   << "MPI_Recv failed"
-                        << Foam::abort(FatalError);
-                }
+//                 if
+//                 (
+//                     MPI_Recv
+//                     (
+//                         &value,
+//                         MPICount,
+//                         MPIType,
+//                         slave,
+//                         tag,
+//                         PstreamGlobals::MPICommunicators_[comm],
+//                         MPI_STATUS_IGNORE
+//                     )
+//                 )
+//                 {
+//                     FatalErrorIn
+//                     (
+//                         "void Foam::allReduce\n"
+//                         "(\n"
+//                         "    Type&,\n"
+//                         "    int,\n"
+//                         "    MPI_Datatype,\n"
+//                         "    MPI_Op,\n"
+//                         "    const BinaryOp&,\n"
+//                         "    const int\n"
+//                         ")\n"
+//                     )   << "MPI_Recv failed"
+//                         << Foam::abort(FatalError);
+//                 }
 
-                Value = bop(Value, value);
-            }
-        }
-        else
-        {
-            if
-            (
-                MPI_Send
-                (
-                    &Value,
-                    MPICount,
-                    MPIType,
-                    Pstream::masterNo(),
-                    tag,
-                    PstreamGlobals::MPICommunicators_[comm]
-                )
-            )
-            {
-                FatalErrorIn
-                (
-                    "void Foam::allReduce\n"
-                    "(\n"
-                    "    Type&,\n"
-                    "    int,\n"
-                    "    MPI_Datatype,\n"
-                    "    MPI_Op,\n"
-                    "    const BinaryOp&,\n"
-                    "    const int\n"
-                    ")\n"
-                )   << "MPI_Send failed"
-                    << Foam::abort(FatalError);
-            }
-        }
+//                 Value = bop(Value, value);
+//             }
+//         }
+//         else
+//         {
+//             if
+//             (
+//                 MPI_Send
+//                 (
+//                     &Value,
+//                     MPICount,
+//                     MPIType,
+//                     Pstream::masterNo(),
+//                     tag,
+//                     PstreamGlobals::MPICommunicators_[comm]
+//                 )
+//             )
+//             {
+//                 FatalErrorIn
+//                 (
+//                     "void Foam::allReduce\n"
+//                     "(\n"
+//                     "    Type&,\n"
+//                     "    int,\n"
+//                     "    MPI_Datatype,\n"
+//                     "    MPI_Op,\n"
+//                     "    const BinaryOp&,\n"
+//                     "    const int\n"
+//                     ")\n"
+//                 )   << "MPI_Send failed"
+//                     << Foam::abort(FatalError);
+//             }
+//         }
 
 
-        if (Pstream::master(comm))
-        {
-            for
-            (
-                int slave = Pstream::firstSlave();
-                slave <= Pstream::lastSlave(comm);
-                slave++
-            )
-            {
-                if
-                (
-                    MPI_Send
-                    (
-                        &Value,
-                        MPICount,
-                        MPIType,
-                        slave,
-                        tag,
-                        PstreamGlobals::MPICommunicators_[comm]
-                    )
-                )
-                {
-                    FatalErrorIn
-                    (
-                        "void Foam::allReduce\n"
-                        "(\n"
-                        "    Type&,\n"
-                        "    int,\n"
-                        "    MPI_Datatype,\n"
-                        "    MPI_Op,\n"
-                        "    const BinaryOp&,\n"
-                        "    const int\n"
-                        ")\n"
-                    )   << "MPI_Send failed"
-                        << Foam::abort(FatalError);
-                }
-            }
-        }
-        else
-        {
-            if
-            (
-                MPI_Recv
-                (
-                    &Value,
-                    MPICount,
-                    MPIType,
-                    Pstream::masterNo(),
-                    tag,
-                    PstreamGlobals::MPICommunicators_[comm],
-                    MPI_STATUS_IGNORE
-                )
-            )
-            {
-                FatalErrorIn
-                (
-                    "void Foam::allReduce\n"
-                    "(\n"
-                    "    Type&,\n"
-                    "    int,\n"
-                    "    MPI_Datatype,\n"
-                    "    MPI_Op,\n"
-                    "    const BinaryOp&,\n"
-                    "    const int\n"
-                    ")\n"
-                )   << "MPI_Recv failed"
-                    << Foam::abort(FatalError);
-            }
-        }
-    }
-    else
-    {
+//         if (Pstream::master(comm))
+//         {
+//             for
+//             (
+//                 int slave = Pstream::firstSlave();
+//                 slave <= Pstream::lastSlave(comm);
+//                 slave++
+//             )
+//             {
+//                 if
+//                 (
+//                     MPI_Send
+//                     (
+//                         &Value,
+//                         MPICount,
+//                         MPIType,
+//                         slave,
+//                         tag,
+//                         PstreamGlobals::MPICommunicators_[comm]
+//                     )
+//                 )
+//                 {
+//                     FatalErrorIn
+//                     (
+//                         "void Foam::allReduce\n"
+//                         "(\n"
+//                         "    Type&,\n"
+//                         "    int,\n"
+//                         "    MPI_Datatype,\n"
+//                         "    MPI_Op,\n"
+//                         "    const BinaryOp&,\n"
+//                         "    const int\n"
+//                         ")\n"
+//                     )   << "MPI_Send failed"
+//                         << Foam::abort(FatalError);
+//                 }
+//             }
+//         }
+//         else
+//         {
+//             if
+//             (
+//                 MPI_Recv
+//                 (
+//                     &Value,
+//                     MPICount,
+//                     MPIType,
+//                     Pstream::masterNo(),
+//                     tag,
+//                     PstreamGlobals::MPICommunicators_[comm],
+//                     MPI_STATUS_IGNORE
+//                 )
+//             )
+//             {
+//                 FatalErrorIn
+//                 (
+//                     "void Foam::allReduce\n"
+//                     "(\n"
+//                     "    Type&,\n"
+//                     "    int,\n"
+//                     "    MPI_Datatype,\n"
+//                     "    MPI_Op,\n"
+//                     "    const BinaryOp&,\n"
+//                     "    const int\n"
+//                     ")\n"
+//                 )   << "MPI_Recv failed"
+//                     << Foam::abort(FatalError);
+//             }
+//         }
+//     }
+//     else
+//     {
         Type sum;
 
         MPI_Allreduce
@@ -206,7 +206,7 @@ void Foam::allReduce
         );
 
         Value = sum;
-    }
+//     }
 }
 
 
diff --git a/src/foam/matrices/lduMatrix/solvers/AMG/interfaces/ggiAMGInterface/ggiAMGInterface.C b/src/foam/matrices/lduMatrix/solvers/AMG/interfaces/ggiAMGInterface/ggiAMGInterface.C
index 95e389e84..cd7dd75a1 100644
--- a/src/foam/matrices/lduMatrix/solvers/AMG/interfaces/ggiAMGInterface/ggiAMGInterface.C
+++ b/src/foam/matrices/lduMatrix/solvers/AMG/interfaces/ggiAMGInterface/ggiAMGInterface.C
@@ -97,7 +97,7 @@ void Foam::ggiAMGInterface::initFastReduce() const
     // Note: reduce with a comm will only be present on processors containing
     // master or slave faces.  Other processors created a dummy map above
     // HJ, 20/Sep/2016
-    reduce(zoneProcID, maxOp<labelField>(), tag(), comm());
+    reduce(zoneProcID, maxOp<UList<label> >(), tag(), comm());
 
     // Find out where my zone data is coming from
     labelList nRecv(Pstream::nProcs(), 0);
@@ -340,7 +340,6 @@ Foam::ggiAMGInterface::ggiAMGInterface
     // On the fine level, addressing is made in a labelListList
     if (fineGgiInterface_.fineLevel())
     {
-        Info<< "fineGgiInterface start: " << lTime_.elapsedCpuTime() << endl;
         // This addressing defines how to interpolate for all zone faces
         // across the interface
         const labelListList& fineAddr = fineGgiInterface_.addressing();
@@ -348,6 +347,10 @@ Foam::ggiAMGInterface::ggiAMGInterface
 
         // Perform analysis only for local faces
         // HJ, 22/Jun/2016
+
+        label curMasterProc, curSlaveProc;
+        long curMaster, curSlave;
+
         forAll (fineZa, fineZaI)
         {
             // Get the local face (from zone) to analyse
@@ -358,10 +361,10 @@ Foam::ggiAMGInterface::ggiAMGInterface
 
             forAll (curFineNbrs, nbrI)
             {
-                long curMaster = -1;
-                label curMasterProc = -1;
-                long curSlave = -1;
-                label curSlaveProc = -1;
+                curMaster = -1;
+                curMasterProc = -1;
+                curSlave = -1;
+                curSlaveProc = -1;
 
                 // Note.  Signalling in global clustering requires
                 // me to recognise clustering from separate
@@ -527,24 +530,27 @@ Foam::ggiAMGInterface::ggiAMGInterface
                 }
             } // end for all current neighbours
         } // end for all fine faces
-        Info<< "fineGgiInterface end: " << lTime_.elapsedCpuTime() << endl;
     }
     else
     {
         // Coarse level, addressing is stored in faceCells
         // This addressing defines which faces from zone are local
-        Info<< "coarseGgiInterface start: " << lTime_.elapsedCpuTime() << endl;
+
         // Perform analysis only for local faces
         // HJ, 22/Jun/2016
+
+        label curMasterProc, curSlaveProc;
+        long curMaster, curSlave;
+
         forAll (fineZa, fineZaI)
         {
             // Get the local face (from zone) to analyse
             const label ffI = fineZa[fineZaI];
 
-            long curMaster = -1;
-            label curMasterProc = -1;
-            long curSlave = -1;
-            label curSlaveProc = -1;
+            curMaster = -1;
+            curMasterProc = -1;
+            curSlave = -1;
+            curSlaveProc = -1;
 
             // Note.  Signalling in global clustering requires
             // me to recognise clustering from separate
@@ -709,7 +715,6 @@ Foam::ggiAMGInterface::ggiAMGInterface
                 nAgglomPairs++;
             }
         } // end for all fine faces
-        Info<< "coarseGgiInterface end: " << lTime_.elapsedCpuTime() << endl;
     } // end of else in fine level (coarse level)
 
     // Since only local faces are analysed, lists can now be resized
@@ -721,7 +726,7 @@ Foam::ggiAMGInterface::ggiAMGInterface
     // In order to assemble the coarse global face zone, find out
     // how many faces have been created on each processor.
     // Note that masters and slaves both count faces so we will
-    //  only ask master sizes to count
+    // only ask master sizes to count
     labelList nCoarseFacesPerProc(Pstream::nProcs(), 0);
 
     nCoarseFacesPerProc[Pstream::myProcNo()] = nCoarseFaces;
@@ -731,7 +736,10 @@ Foam::ggiAMGInterface::ggiAMGInterface
     // contact with the GGI interface will have zero zone size.
     // This needs to be handled separately in the initFastReduce
     // HJ, 20/Sep/2016
-    reduce(nCoarseFacesPerProc, sumOp<labelList>(), tag(), comm());
+
+    // Optimised comm: Wait for info from previous processor, add your
+    // number of coarse faces and pass to next processor
+    reduce(nCoarseFacesPerProc, sumOp<UList<label> >(), tag(), comm());
 
     // Coarse global face zone is assembled by adding all faces from proc0,
     // followed by all faces from proc1 etc.
diff --git a/src/foam/primitives/ints/label/label.H b/src/foam/primitives/ints/label/label.H
index bdbfee903..89de13388 100644
--- a/src/foam/primitives/ints/label/label.H
+++ b/src/foam/primitives/ints/label/label.H
@@ -55,6 +55,9 @@ Description
 # undef  FOAM_LABEL_MAX
 # define FOAM_LABEL_MAX INT_MAX
 
+// Define identifier for label type for int
+# define WM_INT
+
 # include "int.H"
 # include "long.H"
 # include "longLong.H"
@@ -80,6 +83,9 @@ namespace Foam
 # undef  FOAM_LABEL_MAX
 # define FOAM_LABEL_MAX LONG_MAX
 
+// Define identifier for label type for long
+# define WM_LONG
+
 # include "int.H"
 # include "long.H"
 
@@ -105,6 +111,9 @@ namespace Foam
 # undef  FOAM_LABEL_MAX
 # define FOAM_LABEL_MAX LLONG_MAX
 
+// Define identifier for label type for long long
+# define WM_LLONG
+
 # include "int.H"
 # include "long.H"
 # include "longLong.H"