Is it true that you can tan more under water?

Is it true hot water pipes can freeze before cold water pipes if no water is drawn from either for a few days?

• I heard that there can be a difference in the water pressure in the two feed pipes. The cold water pipe is under more pressure than the hot water pipe and because of this, the hot water feed will freeze first. Can this theory be substantiated? It would seem that the hot water line would not be entirely hot - if it hasn't been run recently. We are concidering a kitchen sink with the cabinet doors closed. The house is new and well insulated but the indoor temp has been left at a mere 45 F. The outside temp is at -10 F. Can the pipes freeze? Which will freeze first?

• Answer:

  The answer is in the chemistry. Hot water dissolves solid micro particles to a greater degree thus changing (and lowering) the temperature at which ice crystals form. I cant really explain this to a further degree as I am not a science geek. However I am a maintenance technician for an apartment complex in Flagstaff Arizona, I have recently been gifted with an interesting first hand experience of this phenomenon. The night of Jan.1, 2011, temperatures reached approximately -20F. The combination of extreme lows for the area, and some poor insulating practices dating to original construction 15 years ago, have lead to many frozen and bursting pipes. Many tenants were out of town for the holidays and may not have reported temporarily frozen pipes. Also, all but one of the broken pipes were on the ground floor of the two story complex. Here is the approximate data: 150 apartment units total 90-100 Frozen HOT H2O pipes 50-60 Frozen COLD H2O pipes 15 HOT H2O pipes Broken 3 COLD H2O pipes Broken