The boiler room is where the heat of the house is made. It is read as stored pressure, drive or emotion; a hissing or overheating boiler as tension that needs a safe release.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.