Why do hot water pipes ALWAYS freeze before cold water pipes ?

Question

First I thought it had to do with usage, but even if the last water used for the day is hot, those pipes will freeze before the cold water......and now my friends are seeing the same thing.....

Answer 1

They don't if they are both exposed evenly to the cold. If you are having this problem, then I would say that the hot water pipe is exposed or closer to the cold source. Remember, in most cases there isn't hot water in the pipes ready to use when you demand it. The water in the pipes cools between demand. This is why when you turn on the hot water tap it takes a few seconds to start getting warm.

Answer 2

The water heater is fed directly from the cold water line, so both systems recieve equal water pressure. As far as the hot water line reaching the same temperature as the cold water line, yes, depending on the insulation, the hot water pipe, if no water is drawn through it, will eventually reach ambient temperature. The local radio station has been advising people to leave their cupboard doors open to allow heat to get to the wall where the pipes are, but I am kind of taking this with a grain of salt. It is true that any little bit helps, but if cabinet doors were good insulation, we would be lining our walls with them. as far as one pipe freezing before the other, I would almost think that if a person is going to put pipe insulation on only ONE pipe, they would put it on the hot line and not the cold line, which would give it more freezing protection. I would think that with a new, well insulated house, in weather that is not unusually cold for the region, there would not be a great deal of danger, though you say that you are letting the interior temperature stay cooler than is usual for an inhabited house; and that invites the possibility of a freeze-up. sounds like you may be away from the house? I'd suggest if you have an emergency contact, you think about having them boost the temperature a bit, and run some water from each tap, just to check for a frozen pipe.

Answer 3

even if it is a hot water pipe, with no water flowing through it at the moment, it becomes a 'cold' water pipe fast. most this is caused if because there isnt any pipe insulation on the pipe and if you live in a trailer the hot water line runs near the outside and in the closet the tank sits in which gets almost as cold as the outside.

check the insulation on the pipes, you can also try heat tape.

Answer 4

Yes, hot water pipes will freeze before cold. You are right.

That is because the Oxygen in the water itself is driven off when heated It goes to the highest level in the tank and it is removed constantly by usage. Thus that compressibility of that oxygen is gone and it will freeze and crack before its cold water cousin(which still contains some oxygen) right next to it that experiences the same coldness.

Answer 5

If we assume the same sizes of pipes ,we will find that mass(amount) of water is less in hot pipes, occupying the volume equal to that of cold water.While cooling water occupies more volume,which becomes readily available in Hot pipes.compared to cold pipes.

Answer 6

Scientific answer from College Physics Prof. when I was in Engineering School :
Water gives off heat at a variable rate, increasing steadily as the heat of the water temperature rises. therefore, hot water loses heat faster than cold water. Result: hot water pipes freeze first, and ice cube trays filled with warm to hot water will freeze faster than those filled with cold water.

Answer 7

The Scientist or Scietifically educated person would be correct , all answers are good and a good explanation but the transition from hot to cold is faster than that from cold to colder....

Answer 8

Excellent answers

Answer 9

It's good

Answer 10

They don't.
It is a myth.