Open undebelly - trying to keep the tanks from freezing

[jcussen]

10 minutes ago, Big5er said:

Say what??

The Principles of Evaporative Cooling

As water is evaporated, energy is lost from the air, reducing the temperature. Two temperatures are important when dealing with evaporative cooling systems.

Dry Bulb Temperature

• This is the temperature that we usually think of as air temperature, measured by a regular thermometer exposed to the air stream.

Wet Bulb Temperature

• This is the lowest temperature that can be reached by the evaporation of water only.

When considering water evaporating into air, the wet-bulb temperature, as compared to the air's dry-bulb temperature, is a measure of the potential for evaporative cooling. The dry and wet bulb temperature can be used to calculate the relative humidity.

Evaporation will take place when the humidity is below 100% and the air begins to absorb water. Any given volume of air can hold a certain amount of water vapour and the degree of absorption will depend on the amount it is already holding.

The term humidity describes how much water is already in the air; relative to the amount it is capable of holding. Air is saturated when it cannot hold any more water. Imagine it as a sponge, if the sponge held half as much water as it was capable of holding, it would be 50% saturated. In the case of air, we would describe the Relative Humidity as being 50%.

Pretty much exactly what I said. Thanks for affirming it.

[Barbaraok]

It is all HEAT TRANSFER.   Heat flows from HOT to COLD.   In still area, a little heat will be transferred from inside the pipe to outside (assuming water in pipe is above 0 C, 32F) of the pipe to the air around the pipe.  If the air is still that extra heat will slowly move on to other air molecules around it, But if you have wind blowing, that heat moves away quickly, meaning more heat from the water moves through the pipe and out quicker than if the air was still.  Now if you have the water inside the pipe at a constant trickle, then the heat sink of the water will constantly be replaced by more water above freezing, but if the water isn't moving, it will cool a little quicker if the wind is blowing.

[bigjim]

YaaaRome never says stuff like that and remember this guy is a sailor like Kirk, They might actually do it.l

I have faired pretty well up here. It is not always as bad as tonight and tomorrow night but it is still a little nerve wracking when it gets down and stays down for extended periods.  Sunshine in the day can make a big difference in what happens even if it is still pretty cold.  I did make the mistake of almost letting the black tank get too full a few years ago and I was sweating it as there was not an alternative but a 5 gal. bucket.  If it has been cold long I try to give it a day or 2 to loosen up before I try dumping. I have  use an old hair dryer on the valves if I was in doubt.  The hair dryer gave out as did the hair and I bought a cheap heat gun from Harbor Freight that I use occaisionally in a pinch but they can get pretty hot so I use the lower setting mostly and am careful since I hate damaging stuff when I am trying to make it work.  I am double socking it in the bed tonight with the long johns.  This has been my experience so far which just a little over 20 or so years but sometimes I have worried a little. Heck if I didn't have an appt. w/Dr. on Jan 2, I would try to be at least as far south as you. I did winter 7 times voluntering at Cedar Hill SP just outside of Dallas and never had any big issue until tornado season kicked it.

 

I forgot to tell about a fresh water under the bed in a TT in the mountains outside of Albq. that was half full an sat there over 5 years in an unheated uncooled TT an never busted the tank.  I don't know about any of the lines or pump though.  I know this first hand not annecdotally. They just sold this trailer this fall.

[Big5er]

56 minutes ago, jcussen said:

Pretty much exactly what I said. Thanks for affirming it.

You need to go re-read your own posts. You said swamp coolers do not add humidity to the air. I say they do...and suddenly you agree. Way to switch sides in mid argument. I guess now that you agree with me we are done. 

Btw: you never answered my other question. Will your swamp cooler keep my ice cream frozen? I assume, since you won't answer, that you know they will not. Wind chill will also not freeze pipes when the ambient temp is not below freezing.

[Kirk W]

12 hours ago, DavidCD said:

I've put a couple of gallons of the pink RV antifreeze in each of my tanks but it sounds like that's not going to be very effective once we put in several gallons of waste water.

Diluting of antifreeze does impact the freezing temperature of it but your addition of the "pink stuff" would still lower the freezing temperature but how much is hard to know. I suspect that adding it with your tanks empty would put a much higher concentration of antifreeze into the pipes next to the valves and that it probably would not mix as much with what goes into the tanks and so should lower the temperature that your valves would freeze. It should also mean that if they should freeze it will be less difficult to thaw things out. If you can go several days without dumping you should be OK anyway as it looks like this will be over by Wednesday. 

[Kirk W]

11 hours ago, Barbaraok said:

It is all HEAT TRANSFER.

And any time that liquid changes into a gas it must absorb energy in the form of heat. That means if water evaporates it always removes heat from whatever it is in contact with. That is the reason that evaporative coolers & RV refrigerators work. It is also the reason that bridges on a wet highway sometimes freeze and are icy with the air temperature remaining above 32° F. 

[bigjim]

Big BTW.  1st. what Kirk said about adding pink liquid to tank after dumping is what I do just to get it down in the valve area. I only use much when it is going to be extreme like tonight.  All of this is mainly for the black tank unless I am traveling and boondocking enroute.

The big BTW is don't drip the faucets unless you are on a sewer hook up. That should go without saying but humans will screw up at times.  I got real close on this once. I have the sort of deep shower and the water was about halfway up when I caught it. Much more and it would have started to flood the TT.    13 degrees on the in/out thermomter when I made the early am restroom break and at 12.9F just a minute ago. Supposed to be 8F tonight w/0 degree wind chill and only in the 20's tomorrow.  Gonna be a cold walk across the VA parking lot when I finally find a parking spot. Hopefully the south 40 will have a spot without too much trouble vs trying to snatch one of the close in spots.

 

[Pat & Pete]

41 minutes ago, bigjim said:

The big BTW is don't drip the faucets unless you are on a sewer hook up.

You really should add the fact that a sewer hook up will do little good if the valve is closed . 

 

43 minutes ago, bigjim said:

That should go without saying but humans will screw up at times.

That^ .

[bigjim]

Surely you don't expect me to remember everything all at once.  heck I am just happy I found the bathroom at the 4am call of nature this morning.

[Pat & Pete]

1 minute ago, bigjim said:

Surely you don't expect me to remember everything all at once.  heck I am just happy I found the bathroom at the 4am call of nature this morning.

LOL ... I guess we can let it slide , being it's New Years day morning and all . 

[Barbaraok]

In order for water to 'freeze' the temperature lowers so that the H2O molecules slow down enough to line up correctly.  For H2O, the structure can be represented by /\ with the O at the top of the triangle and a H at each end.   The trick is that the oxygens then rotate so that they look at a H end of the next water molecule, and every hydrogen will line up to only look at an oxygen. This is called hydrogen bonding, and in order to do it, they must move around and apart - which is why water EXPANDS as it freezes, why it forms six-sided snow flakes, why ice floats, and why life exists on this planet.  If you introduce other molecules into the mix, it disturbs the water molecules, they can't line up correctly and the temperature at which they slow down enough to become a solid must drop.    Anything can be used to 'disrupt' (we use NaCl on sidewalks and roads) the hydrogen bonds.  Organic glycols work well in things like radiators and tanks.     Alcohols also work well and all body fluids  like urea also will lower the freezing point.

OK - class dismissed