I have no cold water upstairs. [Hot and Warm] I went down to kitchen and ran it. It went: cold - warm - and then cold again. The same thing happened in the downstairs bathroom and on the first floor laundry sink. The cold line in the garage is warm as well. The cold line on top of the gas water heater is warm, but where it tees off to the downstairs bathroom is cold. No leaks anywhere. The line into the house is cold.

It is 65 degrees outside and has been over 50 for four days. Not likely a frozen pipe. Or could this by the after effect of a frozen pipe that didn't burst, but merely thawed?
I hope I have given you enough to come up with a place for me to start.

Do you have a recirculator on your hot water line, like a Demand system?

Well... the problem is solved now. I shall post details though, as they may help someone else. I got a little curious after writing my first post... something about the idea of cold then warm then cold[er] again made me think in my automotive knowledge, of something needing to be bled. I went down to the spigot in the garage again. It felt cold now. I opened the valve on the line and heard/felt a loud bang. As I knew this to be a sign of air in the line, I hooked up the garden hose and ran the water. Cool at first... spit a few times... cold. I drained the hose again as winter isn't over, and then I drained from the valve to the spigot. Ever since, Every sink in the house is cold as it should be... hot works well too.

Soooo... next question of course... What causes air in water lines? How can I stop it? Do I need to do anything more now?

Thanks in advance

Do you have a recirculator on your hot water line, like a Demand system?

Not that I know of. Hey, I used to work in Wheaton. It was Jones Spacelink then but who knows what now. [1996] Small world. :cool:

Another question... sewer lines and fresh water lines are completely separate right? No risk of that air coming from sewer gas is there?