Myst Island -- The cabin. What does boiler do?

There are large cracking noises when the boiler is fully powered. Where are they coming from? Inside or outside the cabin? Look up?

There are two different noises. One when the boiler is powered up. An another when the boiler was powered up and is now powered down.

Try to figure out what sound goes with what reaction.

Go back to Myst Island -- The cabin. Boiler lit.