In the snow- tanks below freezing

Hi 2oldman,

Actually it is possible to "super cool" water to about -43.8 C (-55 f) without it turning into ice. Not likely to happen in the waste tank of an RV.

So yes, it is quite possible to have ice at 0 c and also water at 0 c.

What I was trying to point out is that to change from liquid to solid requires about 347 watts of energy to be removed from the container for every gallon of liquid. For those who are more used to a BTU measurement that works out to approximately 1184 btu's

As 750 watts is one horsepower--that is one heck of a lot of energy.

It also means that draining the tanks for a 'one night stand' with cold weather is not only fairly useless, but not even desirable. The less liquid there is the easier it is for it to freeze.

2oldman wrote:

pianotuna wrote:
The "loss" of energy to the environment is about 347 watts to turn one US gallon of water at 0 C into ice at 0 C (32 f)....The water has to give up energy to the environment for it to change phase from liquid to solid (commonly referred to as ice). Does that make it clearer?

I can understand losing energy, what doesn't seem right is the '..water at 0 C into ice at 0C. '

Water can't be both water and ice at the same time..can it? Is that a typo?

According to info from Georgia State University regarding phase change from liquid water to ice and vice versa, it takes about 80 calories per gram to change water to ice (energy given up) or ice to water (energy added). That is what I gleaned from it anyway.

Here is a link that may help: Clicky

My recollection from chemistry class is that 0c is the only temperature that water can be either liquid, solid, or gas(vapor).

pianotuna wrote:
The "loss" of energy to the environment is about 347 watts to turn one US gallon of water at 0 C into ice at 0 C (32 f)....The water has to give up energy to the environment for it to change phase from liquid to solid (commonly referred to as ice). Does that make it clearer?

I can understand losing energy, what doesn't seem right is the '..water at 0 C into ice at 0C. '

Water can't be both water and ice at the same time..can it? Is that a typo?

Hi 2oldman,

The water has to give up energy to the environment for it to change phase from liquid to solid (commonly referred to as ice). Does that make it clearer?

2oldman wrote:

pianotuna wrote:
The "loss" of energy to the environment is about 347 watts to turn one US gallon of water at 0 C into ice at 0 C (32 f).

Something not quite right about that statement.

pianotuna wrote:
The "loss" of energy to the environment is about 347 watts to turn one US gallon of water at 0 C into ice at 0 C (32 f).

Something not quite right about that statement.

Your toilet will work with rv antifreeze or salt, so winterize the entire system including the fresh water tank.

Use bottled water for drinking and washing.

That should keep the wife happy.

I'm surprised I haven't seen any mention of the dump lines. While I have never had any problems with my dump tanks freezing and cracking, on older un insulated trailers I've owned I have had the gray line freeze up and crack prior to the dump valve, with low temps only getting down to the double digit range. It's part of why I always made sure my later rigs had insulated headed underbelly's with enclosed dump valves.

You'll be OK.
Long time ago we had a 'new generation' Prowler (not built as well as the old ones), and were staying in the Grand Tetons one night. I knew the tanks were close to full, and went to get in line to dump them.

There were, no kidding, 25 rigs in line. One-holer dump station. I figured I'd be waiting there until long after dark, not my favorite time to set up - especially in an unfamiliar campground. So we found our spot and set up anyway, and just minimized our water use.

It was 50° that afternoon, and in the low 40s when we went to bed after looking at the beautiful, beautiful starry evening; I got up during the night and started the furnace because it was starting to get REALLY cold in the trailer. When I went out the next morning to walk the dogs, my nose prickled like it was REALLY cold. And it was. -2°. Holey cow.

I'd left the truck hooked up because we were going to be traveling the next day, and it was 7:30 AM when we got done with breakfast, and knowing the gray was full, we left the dishes to sit and got about leaving.

I got to the dump station and pulled the handle - NOTHING from the gray tank. Black flowed just fine. Scratched my head, said, "Well okay, can't do anything, and it'll thaw in a couple hours", so away we went.

Along about 12:30 we'd been traveling about 4 hours and the outside temperature was back in the high 40s; we found a place where we could dump the gray, and it dumped just fine. No harm done.
But I'll never try that test again... Current trailer is 4-season with enclosed and heated tanks.

First year RVing we were staying in West Yellowstone in September. The forcast was for the temperature to dip into, oh my good, the low 30's. The park hosts were new and were from Southern California... they went as far as printing out sheets of paper warning everyone of the "freeze" coming and to make sure your rig is fully winterized. :) It was very amusing.