I'm in Dallas where we are experiencing freezing temperatures. The house was built about 25 years ago, i.e. reasonably modern. My water heater (natural gas) is in my open-air attic (edit: and supplied via copper tube). I have just placed a thermometer there to check temps; I believe from feel it is not as cold as outside but it is quite cold and probably freezing temp in that space, but no wind to exacerbate the situation. (edit: yes, temp appears to be ~25°F in attic right now.)
So, the issue...my cold water is running OK everywhere in my house, but my hot water is not at all. The hot water heater fires up when I turn up the thermostat on it, so no issues with its operation. Can I conclude that the feed/pipe from some point inside my house where the line splits off cold feed to the rest of the house and up to the water heater has frozen? If so, should I be overly concerned at this point (it's 8a.m.)? Is there a smart/easy way to locate the point of the blockage if this is the case?
I'll note that if pipe is frozen it's odd because this is the first time in ~20 years this has happened, despite similar freezing conditions in year's past, e.g. the week long freezing-cold snap last year that made the news everywhere for freezing up all the wind turbines here in TX.