The Low Hum Below

I scrambled down the bottom rungs of the fire escape and slipped straight through the cracked basement window into the boiler room. It's warm down here! Rows of fat green pipes crisscross along the ceiling, and the big water heater gave a steady, rhythmic rumble. Right near the drainage valve, I spotted a tiny brass pressure gauge with its glass face fogged up. I pulled a clean cotton rag from my pocket and wiped it down until the needle showed clear as day—right in the safe green zone! Everything's ticking along just fine.