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Open undebelly - trying to keep the tanks from freezing


DavidCD
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OK - We're currently staying at an RV park in College Station, Texas ;  apparently we didn't go south far enough to avoid the freezing weather - the forecast is for nighttime temps in the upper teens/low twenties for the next 3-5 days.

Our Puma travel trailer does not have an enclosed underbelly nor, insulated tanks and we're trying to make use of the onboard plumbing.   I've encased the water supply hose in insulating foam tubes and wrapped the fresh water and lowpoint drains.   I have read comments on from campers who have used their exposed tanks and valves during freezing weather by pouring a gallon of the pink RV antifreeze in each tank after each dump and storing their dump hose in a plastic bag inside the RV to keep it from freezing and getting brittle.    

So, the local weather guys are now saying it might get a bit colder for a bit longer than they originally forecast (I want their job - they can say anything an still have a job the next day).   The label on the antifreeze bottle (the pink, SuperTech antifreeze from Walmart) says it is "formulated to provide complete protection to -50°F.  Some slush may appear at approximately 0°F, but this is not harmful to your water system."

The wording on the label makes it sound like I'll be OK; however, I have just read some comments saying that the pink antifreeze looses its freeze protection when it gets mixed with water (although water is one of its ingredients) .   That being the case, then there must be some dilution factor beyond which the pink stuff no longer provides any freeze protection -  does anybody know the ratio of pink antifreeze/water that will still provide freeze protection to 20°F   ?

Has anyone else used their exposed tanks during freezing weather by adding antifreeze to the tanks?

Thanks for any feedback.

DavidCD

Edited by DavidCD
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Heat tape would work for the valves and other items. Don't see anything wrong with putting in the pink stuff either. We also use incandescent light bulbs to keep things warm.

Are the campground faucets insulated? If not, let them drip all night. We have been in TX campgrounds when there is an unexpected freeze where the campground water is turned off.

Good luck...............

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David, this chart may be of some help to you: http://mystarbrite.com/public/pdf/PG_Antfreeze_Dilution_Chart.pdf

You would be surprised as to how well your trailer does for the temps expected. I wound up staying inmy2006 Dutchmen that had exposed tanks in temperatures that ranged from about 40 during the day down to about 25 at night. I even left the furnace off while I slept and had no problem with anything freezing.

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Thanx for your feedback SWharton -

Yeah, the RV park is leaving their water systems turned on but, I insulated their faucet & supply pipe at my site and enclosed the connection in a cardboard box (the connection is under a slideout so the box should stay dry).

So, all the RV supply stores are closed for the weekend and it's a too late to order anything online so, the only thing I have to work with is the the pink RV antifreeze and, if everything gets frozen, my wife's hair dryer.

DCD

 

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Mntom:

Thanks for the AF dilution chart - yep, it does look like the stuff goes flat pretty quick when it gets mixed with water -

We also have stayed in our TT in temps down to the mid 20s and didn't have a problem but, the weather guys are now talking about temps in the upper teens with 25 mph winds - I suspect those temps & wind chill will go below the safe limit.

Well, it may be a long, cold week ...

Thanks again.

DCD

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MnTom :  Thanx for the "open sites" report - I'd like to head that way but, we're holding in here for grand parenting requirements.    I used to work out of Port O'Connor years ago (offshore crewboat skipper) - how did PO hold up under the hurricane this year?   I heard that Rockport & Fulton really got trashed.

DCD

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I doubt you will have any big issues where you are.  For 2 reasons I would not let the gray and black tanks get too full.  I usually like to dump with fuller tanks but in this situation I want them to have room to expand and also allows time for the valves and piping to thaw before I try to dump. Also if you get to full and cannot dump till things thaw a bit where will you take care of business.  I have been in much worse with no issue but I am sweating it a little for the next few days at least as it is going to be somewhat worse than usual here near the Navy base at Memphis. I have wintered here for at least 5 years and so far no problem. My tanks are not covered or insulated at all. I do use a heat tape on the water hose under the foam insulation and haven't had any issues. My fresh tank is inside under the couch.  I have had a couple of freeze ups of the line somewhere going to the kitchen faucet several times when I didn't leave the low cabinet doors open enough and leave a slight drip overnight. I had one earlier this week when I forgot the open cabinet door and drip. I will say Hooray for pex plumbing.  It seems to have saved me more than once.  Today I may go to Lowes an get a second heat tape to wrap around the dump valves since it seems like it may be worse that usually.

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1 hour ago, DavidCD said:

MnTom :  Thanx for the "open sites" report - I'd like to head that way but, we're holding in here for grand parenting requirements.    I used to work out of Port O'Connor years ago (offshore crewboat skipper) - how did PO hold up under the hurricane this year?   I heard that Rockport & Fulton really got trashed.

DCD

POC seemed to come through Harvey pretty good. Other than a few sheds falling over and a lot of roofs it looks like last year! Yea, Rockport and even Port Lavaca got hammered.

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Actually, that isn’t true.  Unless you have insulation covering exposed hose/tank there will be flow of heat from water to hose/tank to the surrounding air, and if wind is blowing, surrounding air will move away and increase heat lost from surface.   It will not be rapid, but it will occur faster than if no wind moves across the surface.  

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44 minutes ago, Barbaraok said:

Actually, that isn’t true.  Unless you have insulation covering exposed hose/tank there will be flow of heat from water to hose/tank to the surrounding air, and if wind is blowing, surrounding air will move away and increase heat lost from surface.   It will not be rapid, but it will occur faster than if no wind moves across the surface.  

Very true and pipes can actually freeze above 32 F if they are wet by evaporative cooling.http://articles.chicagotribune.com/2011-11-22/news/ct-wea-1122-asktom-20111122_1_chill-evaporative-cooling-mortar

Edited by jcussen
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53 minutes ago, jcussen said:

Very true and pipes can actually freeze above 32 F if they are wet by evaporative cooling.http://articles.chicagotribune.com/2011-11-22/news/ct-wea-1122-asktom-20111122_1_chill-evaporative-cooling-mortar

Then explain to me when you would have a situation where you will have evaporative cooling on your rv water hose or tanks. We are not talking about every conceivable possibility, just as it pertains to RVs.

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29 minutes ago, Mntom said:

Then explain to me when you would have a situation where you will have evaporative cooling on your rv water hose or tanks. We are not talking about every conceivable possibility, just as it pertains to RVs.

I am just stating a fact, not implying it applies to every rv. But I will tell you I had a camper that had a fw tank under it, with maybe a 1/2" of fiberglass insulation. Definitely not enough to insulate tank against freezing. Went to change a leaky water pump and found all the insulation soaking wet!  Never froze on me, but this a situation where evaporative cooling could happen. Probably could not happen to OP because his tanks are exposed. Not very likely to happen in an rv, but it is conceivable.

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So, if wind is capable of lowering the temperature below the ambient air temp does that mean as long as it is 40 degrees or so, I can turn off my freezer and take my ice cream and ice cubes outside and just let a fan blow on them?

I'm no scientist but according to NOAA:

Does humidity or being near a large water body affect on wind chill?

When NWS tested the new Wind Chill Temperature Index (WCTI), NWS researchers applied the new index to 12 test subjects. The results of the tests showed that relative humidity was an insignificant weather parameter, affecting the outcome to less than 1 degree. To simplify the calculation, relative humidity was left out of the formula.

http://www.nws.noaa.gov/om/winter/faqs.shtml

Edited by Big5er
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Swamp coolers work by adding humidity into the air. They are more than just "wind". They also do not work in already humid climates. The air is so humid here that you can't add much more and all a swamp cooler does is blow water on everything. Your video also says they work best in HOT, dry climates. That alone suggests that a swamp cooler would not make 40 degrees into 20 degrees or even turn 50 into 30. If it were 35 degrees would your swamp cooler keep my ice cream frozen? I think not. There is a reason you buy an RV with air conditioners and not swamp coolers. 

But I digress, since we were talking wind chill and not air conditioners, swamp coolers or other machinery.

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52 minutes ago, Big5er said:

Swamp coolers work by adding humidity into the air. They are more than just "wind". They also do not work in already humid climates. The air is so humid here that you can't add much more and all a swamp cooler does is blow water on everything. Your video also says they work best in HOT, dry climates. That alone suggests that a swamp cooler would not make 40 degrees into 20 degrees or even turn 50 into 30. If it were 35 degrees would your swamp cooler keep my ice cream frozen? I think not. There is a reason you buy an RV with air conditioners and not swamp coolers. 

But I digress, since we were talking wind chill and not air conditioners, swamp coolers or other machinery.

You are talking about wind chill. Original poster was talking about his tank freezing. And I added that it does not have to be below 32 f for something to freeze. You might look at Kirks attachment. Unless it is raining, water will evaporate at any temp above freezing. When it stops raining, even when fairly cold and humid,  the water on the road goes somewhere. It evaporates. The swamp cooler video was for people who may not understand evaporative cooling. This is pretty basic, when water evaporates it uses heat to do it, no matter what the temp or humidity is, and the surface it is on, becomes cooler. I am not saying this always or even does happen on an rv but it is basic physics and does happen. By the way, swamp cooler do not work by adding humidity,  they work because the water evaporates and cools the air passing over the media the water is on.

Edited by jcussen
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7 hours ago, bigjim said:

I doubt you will have any big issues where you are...    I have been in much worse with no issue ...  here near the Navy base at Memphis.    I have wintered here for at least 5 years and so far no problem.    My tanks are not covered or insulated at all.

Hey BigJim,

Thanks for your reply.   If you're up there near Memphis I'm sure you get much colder temps than we do down here in Texas.  

So, have you been able to use your grey/black tanks all the way through the winter?     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.

DCD

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53 minutes ago, jcussen said:

 By the way, swamp cooler do not work by adding humidity,  they work because the water evaporates and cools the air passing over the media the water is on.

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%.

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Wind chill only effects people, animals and plants, ie. things with moisture.  It will effect pipes IF the pipes are wet.  The wind will increase the heat transfer, but will not lower the temperature by cooling due to evaporation unless there is moisture to evaporate..  If the surface is dry, it will not be any lower than the ambient temperature.  

Spent my career in applied heat transfer and thermodynamics and that is the way it works.

Ken

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