diff --git a/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/constant/gas/fvModels b/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/constant/gas/fvModels
index 6888b483cd..770c1d1159 100644
--- a/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/constant/gas/fvModels
+++ b/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/constant/gas/fvModels
@@ -14,23 +14,6 @@ FoamFile
 }
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-ignition
-{
-    type            heatSource;
-
-    selectionMode   cellSet;
-    cellSet         ignition;
-
-    q
-    {
-        type        scale;
-        scale       squarePulse;
-        start       0;
-        duration    1;
-        value       5e7;
-    }
-}
-
 radiation
 {
     type    radiation;
diff --git a/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/system/gas/fvConstraints b/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/system/gas/fvConstraints
new file mode 100644
index 0000000000..f4231c1dfc
--- /dev/null
+++ b/tutorials/heatTransfer/chtMultiRegionFoam/reverseBurner/system/gas/fvConstraints
@@ -0,0 +1,35 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Version:  dev
+     \\/     M anipulation  |
+\*---------------------------------------------------------------------------*/
+FoamFile
+{
+    format      ascii;
+    class       dictionary;
+    location    "constant";
+    object      fvConstraints;
+}
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+ignition
+{
+    type            fixedTemperatureConstraint;
+
+    selectionMode   cellSet;
+    cellSet         ignition;
+
+    mode            uniform;
+
+    temperature     2000;
+
+    fraction
+    {
+        type            table;
+        values          ((0 0) (0.1 0) (0.2 1) (0.4 1) (0.5 0));
+    }
+}
+
+// ************************************************************************* //