...the plumber is the man who saves 'em all!!
It turns out that what we had was a sort of "embolism" in our water pipes. When an embolism reaches the heart of a human being, death occurs.
As it turns out, when lethal air bubbles such as these reach the heart of a plumbing system, there is the same sort of result. With a lot of noisy drama, to boot. That huge water heater was rocking on its foundations, and we were terrified that not only the water pipes, but the gas line would erupt.
Many, many thanks to our plumber and his wife, who took our frantic calls at six o'clock in the morning. Many more thanks to the employee from Direct Energy, who came in out of the cold, accepted a large cup of tea, and then charged me nothing at all for re-connecting the gas and lighting the pilot for us.
There will be long, hot baths for us all this evening... how nice to be reminded of one of the great blessings, during a cold Canadian winter.