I did the same thing I did once before: I turned the valve the wrong way.
Instead of closing it I opened it so much that water flowed so freely that it made no noise and it shook not at all. It sounded and felt closed. Then I tried to go to bed. But soon after, how long I can't say, I heard dripping.
I wanted to dismiss it as rain, but it was too localized. When I realized where it was coming from I sprinted to the furnace room. The water wasn't coming from there. The water was coming, disturbingly quickly, from above.
At first I misjudged, I thought maybe I'd screwed up something in the bathtub/shower and that was overflowing. I sprinted up stairs and ran into the bathroom to find that everything was fine.
Across the hall, in the bedroom I grew up in, the radiator was spewing water.
A steam heated radiator system isn't designed to handle anything but gas. The furnace always heats steam to the same temperature. That's a problem in the summer because it needs to stay at a constant heat of really fucking hot (internal heat) and entropy says that it will cool so the laws of physics themselves stipulate that it will burn oil and put out heat (not a lot of heat, but some) even when it doesn't actually need to heat anything. That's why once it's warm enough we turn it off.
A newer system built on the same principles would account for the fact that we've gotten much better at heating water, and thus don't really need it ready at a moment's notice every second because it can get ready at close to a moment's notice anyway, and not have the summer problem. But it still wouldn't be designed to handle anything but gas.
When I turned the valve the wrong way I flooded the furnace. Once the furnace was flooded the water had nowhere else to go but where the gas was supposed to escape. That takes it to a network of pipes that end, eventually, at the radiators. They immediately fill up with water. Then it's a simple matter of pressure building up until the water can force itself out of the vents intended to vent excess gas.
At that point they become sprinklers. Dirty sprinklers as I recall.
Turning the valve the right way (which also happens to be the right way, if you do the motion across the top assuming you're facing the same direction as the valve reasoning that brought us "lefty loosey") was the easy part. Most of what I've just finished doing involved running around my house looking for large containers and asking the questions "Is it waterproof?" and "Can I move it?"
I got the heating system to stop spewing water, I'm pretty sure, but clean up is another matter. Tomorrow I was supposed to tell my tale of medication-problems woe to a teacher in hopes of leniency regarding some stuff. Instead I'll be spending tomorrow visting every radiator in the house, wreaking wanton destruction on the area around each, and trying to salvage what can be salvaged and discard the rest in hopes that water damage doesn't turn into a mold infestation.
The other time I made this mistake I was still in high school. I had to leave for school and so my mother was left with the clean up. I don't envy her, and I don't look forward to going through what she had to go through the last time.