Cuprager wrote:
Does anyone know where i can get (or improvise!) a tool that will get
between the fins of my CH heat exchanger to clean it without damaging
it? I have used a stiff brush but it is simply not effective at getting
deep enough between the narrow gaps.

I struggled for damn ages.
Then I discovered that the crap is water soluble, when I took the heat
exhanger off, and washed it in a bucket of water.