Intense fire

Now lets make this fire a little bit more intense.

Duplicate the "new FIRE" layer
Layer -> Duplicate Layer
Rename the newly duplicated layer to "strong fire".



 
Bring up the Hue/Saturation dialog once again
Image -> Adjustment -> Hue/Saturation

This time, make sure "Colorize" is NOT checked.
Set Hue to -20 Saturation and Lightness both at 0.

Set the layer blend mode to "Overlay".