Frozen Pipes.

Aridon wrote:
If you were running the furnace, there shouldn't be anything frozen downstairs unless something is borked. Most rigs have tank heaters as well so you shouldn't have frozen black / grey tanks either. Maybe a frozen exit valve if the ding dongs at the factory decided to put that on the exterior but most that i've seen put the flapper on the inside.

Now IF you are frozen, you need to drop the false wall in your storage compartment and get behind there to see what is going on when the furnace is on. You shouldn't have to leave cabinet doors open to get warm air down there. There should be some vents and heat escaping into the belly to keep it warm. If there isn't, you absolutely must make yourself a vent to keep that space heated. Pretty simple to do, any home depot or lowes will have the parts and tape.

In a pinch you can put a space heater there. While you're in there you should consider adding a smoke detector down there as well.

This is also a good spot to look and see what is going on down there. If there is Ice in the tanks or if you have a frozen water line or even a leak. You can feel the water lines, if something is iced up, you should be able to feel the difference in the line. This has been many hours now of trying to get water, it is either frozen or it isn't. Temps there will either indicate is is possible to freeze or they won't.

Otherwise, make sure your valves are working. Try and get heat to the CG water so you can test on city. Maybe your water pump blew a seal, runs but isn't actually pumping water. Maybe your valves are in the wrong position. Maybe you really do have a freeze, but you should be able to verify that if you look. Nothing beats the laws of physics, it will either be cold enough or it won't. If any pipes run near the extremities check there as well I just can't imagine the underbelly getting cold enough with the furnace running unless they forgot to open a vent down there.

Anyway, good luck tracking down the issue.