Not happy with my plumbing. I got up this noon to find that I didn't have any hot water pressure. My washer's cold water spigot was also dry, and that's on the same pipe as the hot water heater, and so it seemed to be related to the earlier problems I'd had with that same pipe.

Perhaps it froze? But last night was not a record low.. And it was still not working at 1 pm. But it's working fine now at 3:30. Hrm.

I hope my plumber has an idea of how to debug this. If it were me, I'd have to wait and get some more data on whether it's reproducible after another cold night, or try to put in a preventative fix like improving the insulation on that pipe.