diff --git a/applications/solvers/compressible/steadyCompressibleMRFFoam/iEqn.H b/applications/solvers/compressible/steadyCompressibleMRFFoam/iEqn.H
new file mode 100644
index 000000000..eadd3889c
--- /dev/null
+++ b/applications/solvers/compressible/steadyCompressibleMRFFoam/iEqn.H
@@ -0,0 +1,42 @@
+{
+    // Solve the rothalpy equation
+    T.storePrevIter();
+
+    // Create relative velocity
+    Urel == U;
+    mrfZones.relativeVelocity(Urel);
+
+    // Create rotational velocity (= omega x r)
+    Urot = U - Urel;
+
+    fvScalarMatrix iEqn
+    (
+        fvm::ddt(rho, i)
+      + fvm::div(phi, i)
+      - fvm::laplacian(turbulence->alphaEff(), i)
+     ==
+        // Viscous heating: note sign (devRhoReff has a minus in it)
+      - (turbulence->devRhoReff() && fvc::grad(Urel))
+    );
+
+    iEqn.relax();
+
+    eqnResidual = iEqn.solve().initialResidual();
+    maxResidual = max(eqnResidual, maxResidual);
+
+    // Calculate enthalpy out of rothalpy
+    h = i + 0.5*magSqr(Urot);
+    h.correctBoundaryConditions();
+
+    // Bound the enthalpy using TMin and TMax
+    volScalarField Cp = thermo.Cp();
+
+    h = Foam::min(h, TMax*Cp);
+    h = Foam::max(h, TMin*Cp);
+    h.correctBoundaryConditions();
+
+    // Re-initialise rothalpy based on limited enthalpy
+    i = h - 0.5*magSqr(Urot);
+
+    thermo.correct();
+}