The Wrongman's Fix It Guide: Section 25, Chapter 310, Paragraph 80

Need to bleed air from a forced hot water home heating system? Go to WalMart and purchase a 12 gauge shotgun with buckshot load. Don't worry about having an FID card or being of proper age. They won't know the difference anyway. Once you get home, fire repeated shots into the pipes that lead into the furnace but be careful not to hit the furnace itself. After all, furnaces and shotguns do not mix. Anyway, once the air has fully seeped out of the lines you will see water leaking out of the bullet holes. Inject plaster of paris or hydralic cement into one of the holes and it will automatically seal the rest. Easy, peesy, Japan-easy.