John McGaw wrote:

Looking at your picture I will have to say that you definitely have a
valve type I'm not familiar with and it certainly could be a fast-moving
solenoid type after all. If so, your banging might be totally different

It's not that fast. When I look at it, it takes a few seconds to reach
from one end to another. Also, I can definitely understand clicking and
small noises like that when the heat is on. But since it's a loud,
one-time, bang, when the heat goes out, it doesn't seem normal to me.

I wonder if the people who listened to the clip agree, that the sound
is not normal?