I moved into my current house August 15th. Tom and I lived there for about a month alone, without any real problems. Jeffrey moved in about that time and started complaining that he had no hot water. Though it occasionally wasn't super hot for me, I didn't really think it was a problem. So after looking at the water heater one day, realizing I couldn't see the pilot light, and clicking the button a few times, I left it alone. However, the new roommates moved in this week, turned the a/c down fifteen degrees, and my shower was very cold suddenly. I knew that they hadn't showered for hours so I thought about it more that day.
About two in the morning last night Jeffrey and I took a look at the water heater. I discovered shortly that I could see the pilot light if I slid this little piece of metal over. Then I made the discovery that if I moved the little dial to "on" instead of "pilot" a lot more fire came out.
This morning the shower was just a little better.