2. At the beginning of time, Mother Nature decided that thermostatic radiator traps should last about 10 years. This is because thermostatic traps have these flexible metal bellows that open and close a gazillion times a year. Traps do the best they can, but they can't last forever. When they die, they usually do so in the wide-open position because this is the position that will cause you the most grief.

3. Mother Nature also decided that most human beings will be either too cheap, too dumb, or too lazy to repair thermostatic radiator traps. She, too, has a sense of humor.

4. Without thermostatic radiator traps the condensate gets hotter and hotter. Vacuum pumps don't like really hot condensate because they have a tough time pumping it. This is because, in a vacuum, water boils at a lower temperature than it does under atmospheric conditions. Since vacuum pumps produce vacuum (hence the name!), they have a good reason to be concerned about really hot condensate.

5. The red-hot condensate slugs into the vacuum pump, and flashes into great puffs of expansive steam as it hits the pump's impeller thereby causing the pump to run dry. In a few hours, the pump's mechanical seal cracks and spews lava-like condensate across the boiler room floor.

6. The building superintendent shuts off the vacuum pump, and opens the bypass line in hopes that the condensate will be smart enough to return to the boiler by itself. The superintendent has no problem making this decision because he sees no need for any system component he doesn't fully understand. He would bypass the boiler if he could.

7. The condensate now takes its sweet time returning to the boiler. It may make it back by next June if all goes well. Meanwhile, there's a lot of water hammer in the building, which everyone considers normal. It's a steam system, right?

8. The boiler goes off on low water.

9. The superintendent curses under his breath, and then adds raw, icy water to the boiler. If he's a real superintendent, he'll also convince management they should hire a plumber to install an automatic water feeder. With this device, he figures he'll have one less thing to do, and the tenants just might stop banging on his door in the middle of the night.

10. The automatic water feeder does its job, maintaining a safe, minimum water line inside the boiler. The boiler continues to run, sending steam up toward the undersized pipes that continue to hold back the condensate. At some point, the condensate stacks up high enough in the system to build the pressure it needs to return. When it does, it floods the boiler.

11. The superintendent curses the automatic water feeder. He drains water from the boiler and goes back to bed. Within minutes, the cycle begins again, and before you can say "oxygen corrosion" the boiler grows holes big enough to toss a tomcat through.

12. You get hired to install a new boiler. Naturally, you chose a modern, highly efficient, low-water-content steam boiler. Thirty seconds after you start it up, it goes off on low-water. The superintendent calls you a bad name in a foreign language and your sphincter muscle begins to do the mambo.