94 replies to this topic

[ramblinChet]

Very interesting thread - thanks to all who have shared first-hand information.

 

My question is how to design a water system that is operational below freezing?

 

It seems as if we have two different parties to consider - those who will leave heat on all night and those who will not. There also seems to be two primary areas to consider. Area one would be the water tank itself while area two would include all the water lines, valves, pump, fittings, etc.

 

Maybe a simple solution for area two (water lines, pump, etc.) would be to have the ability to drain or pump the entire system back into area one (water tank) so now we are only fighting one battle. I am not familiar with plumbing so please excuse my suggestions but maybe this is a simple as having some sort of valve at the lowest point just above the tank that will permit the system to vent and drain all the water back into the main tank? Or maybe a valve that would prevent more water from being picked up from the main tank and now use the pump to pump all of the water back into the tank through a purge line?

 

Provided we are successful with draining all of the water back into the main tank now we no longer are worried about the pump, water lines, fittings, etc. since they are filled with air. So let's look at the most energy efficient way to prevent the main tank from freezing. We know that water will not freeze if it is moving so maybe some type of aeration system? Farmers use windmill driven aerators to keep ponds from freezing. The marine industry uses bubbles along the hulls of ships to keep that area from freezing and crushing the steel hull. If I have an air system onboard already with a five gallon tank at 150 PSI maybe I could have an aeration system plumbed into my main tank and use a slow release of bubbles to prevent the tank from freezing?

 

Not sure how many hours a system like that would last or how many bubbles are actually required for a given volume of water or maybe surface area is the key metric? I have no doubt that this area has been researched and many experiments have been performed so the information is out there. Maybe even a very small low draw DC powered water pump inside the main tank just to keep the water moving - like a fountain spraying up inside the tank itself?

 

My goal is to build a water system that can be used during freezing conditions when needed. Once I am done using it the system can be placed back into a hibernation mode where it consolidates all the fluid and keeps it from freezing. I spend much time in freezing conditions and I would like to design and build a water system that can be used below freezing temperatures.

 

BTW - I know many take external and internal temperatures but is anyone actually taking the temperature of the water inside the tank? That is critical information to have. Maybe a trigger that when the water temperature drops below 35 degree Fahrenheit the system becomes operational.

Edited by ramblinChet, 23 January 2022 - 04:14 AM.

[Wallowa]

Aeration I believe has been discussed...interesting approach.  Just my take.  FWCs do not have sufficient insulation of water system to prevent freezing in severe low temps...below zero.  And to my knowledge getting all the water out of all the plumbing is damn near impossible; most of it yes, but in the wrong spot and ruptures occur.  Even blowing it out does not clear of water.  Next my hot water tank holds 6 gallons, main tank holds 20 gallons; if you intend to drain the hot water tank into the main tank there must be 5+ gallons of room [hot water tank plumbing only allows 5+ gallons to gravity drain]; so your capacity is 20+ gallons if you want to consolidate all water into the main tank.

 

Grandmother's expression seems apt here:  "You can't make a silk purse out of a sow's ear".  It boils down in my mind to risk vs benefit vs construction design.  Unless you engineer a very effective foolproof system that prevents freezing of the system under all conditions; you run the risk of rupturing plumbing and flooding the camper.   In my view, the resulting damage is just not worth the gain of turning on a faucet for water. 

 

IF, big IF...You have a source of internal heating in the FWC for the entire time during seriously low temps, then maintaining the water system intact is feasible.  BUT you need to also not only maintain the heat when you are in the camper or out of the camper when it is set up but when driving.  Some folks run their propane furnace when driving and when stopped to prevent freezing pipes but personally I think while driving is very risky.  Bottom line is energy. You need electrical reserves and/or propane reserves for any heating.  Winter normally does not offer much solar panel input, so you need massive battery banks, or 110/120 hook-up [small electrical heater great with 110] or run the vehicle with DC/DC charger to keep the battery [s] SOC up to the needs.

 

I have no idea how much current is needed for the use of heated wire wraps; a la the internal heating element in my BB battery.  May not be feasible; again an energy budget issue.

 

So for me with so many variables on a ski trip, I opt for carboy [7 gallon] jugs of water and conserve on usage.  Trading convenience for freedom of worry and protection of my Hawk from a major disaster just does not add up.

 

Just me and I could be wrong.  Would love to see a truly feasible solution that allows use of water system at below zero temps.

Edited by Wallowa, 23 January 2022 - 04:54 AM.

[rando]

This is another case of not trying to reinvent the wheel.   There are plenty of folks on here who regularly use their FWCs  and water system below freezing (myself included).   The solution is the obvious one - you need to heat your water system to keep it above freezing.  There are other folks who aren't comfortable with the necessary attention and risk this entails, and they choose not to use their water system in the winter. 

 

The easiest way to do this is with the furnace and hot water heater.    If you have a shell and are designing your own water system, you are at an advantage - put all your water infrastructure in one cabinet (like in the flatbed models) and then insulate that cabinet.   In this case the hot water heater will provide plenty of waste heat to keep the water system un-frozen as well as lots of thermal ballast.  Even if you need to turn it off for several hours, you will be fine - 6 gallons of water at 140F contains a lot of energy.    Even with the stock FWC (which is only minimally insulated) this works down to the low teens (F), which is about as low as I have tried it.   If you were to add an inch of poly-iso to the water cabinet, then I am sure you would be OK down in the single digits.   At night, when you are running the heater, open the doors to the water cabinet to keep that warm too.   

 

Just be aware that if you loose the ability to heat, you need to be prepared to winterize on the spot or you risk significant damage. 

[Wallowa]

 

Just be aware that if you loose the ability to heat, you need to be prepared to winterize on the spot or you risk significant damage. 

 

 

Agree with Rando's assessment...but for me I need to prepare for sub-zero temps not just into the teens...again 24/7 even when driving to different locations..hence why I also have a heated BB battery so the solar can charge it regardless of how low the temp.

 

All about assumption of risk....

[rando]

Agree with Rando's assessment...but for me I need to prepare for sub-zero temps not just into the teens...again 24/7 even when driving to different locations..hence why I also have a heated BB battery so the solar can charge it regardless of how low the temp.

 

All about assumption of risk....

 

Agreed, I wouldn't try to use the water system in sub-zero (F) temperatures either.   

[rando]

And just to clear up one other misconception - water freezes at the same temperature, moving or not.   Aerating or agitating your water tank won't help the situation (except for the tiny amount of kinetic energy you are introducing into the system).   The reason that famers use an aerator in a pond (or an aerator on a boats hull) is to bring warmer, denser, water from lower in the pond/ocean to the surface to stop the surface freezing - it doesn't actually reduce the freezing temperature of the water. 

[Wallowa]

Ok...but moving water in rivers drops below freeze [ Decades ago I did a dive for Sheriff in Truckee River to retrieve a firearm water was 28 *F and water froze on mask glass when you surfaced]...so moving water, like leaving a pipe dripping, seems to forestall the water from freezing up to a point then you get frozen water falls...kinetic energy?  But moving water can go below freezing.

 

Saw this not a scientific article....

 

 

It is more accurate to say that fast-moving water will not freeze at 32 degrees. The action of the water flowing carries an energy of its own that prevents the water molecules from freezing to each other because they are constantly getting mixed up. This is why the stream on our property don’t freeze solid.

Moving Water Doesn't Freeze, Except in Our Pipes

pickled-prepper.com/2021/02/moving-water-doesnt-freeze-except-in-our-pipes/

Edited by Wallowa, 23 January 2022 - 05:21 PM.

[rando]

This is a common misconception, but water moving in a river with a frozen surface is sill above freezing.    There are three circumstances where water can exist as a liquid below 0C/32F.   Water with a lot impurities (eg salt water), water with no impurities that is not in contact with anything to provide an ice crystal nucleation site (eg cloud droplets suspended in clean air, which leads to freezing rain) or water under extreme pressure (not really applicable, except to the lab or deep oceans).  

 

Not to doubt your experience, but I am guessing the reason your mask froze was the water was very, very close to freezing, and the air was well below freezing, as soon as you exposed your mask to the air, the water froze quickly as it was so close to the freezing point.   

 

Full disclosure, there is a rare situation, when you have extremely rapid radiative cooling of a rivers surface where there is not time for the water to freeze into a continuous sheet and you get something called frazil ice (like an ice slurry) and the water can get slightly super cooled (like 0.01C below freezing).  This is a scientific curiosity, and something that keeps hydroelectric dam managers up at night in Manitoba, but not something that makes a practical difference.

 

The theory behind leaving a tap dripping is not that moving water won't freeze, it is that the open faucet prevents the pressure in the pipe building up and bursting the pipe when the water does freeze and expand.   A second benefit is that the water coming into the pipe is above freezing (from below the frost line) so it is providing some heat to the pipe.   If it is cold enough for long enough, a dripping tap will still freeze.  

Edited by rando, 23 January 2022 - 05:41 PM.

[wicked1]

I use my water all winter.  Rando said all that needs to be said I think.   My last trip I didn't even worry about heating the hot water.. I left it empty the entire time.  My water cabinet is insulated.  (I added foam insulation to the walls).   I was never worried while camping, but was nervous a couple times on the road..  It was fine, tho.

I'll add a couple things.  It's not really the tank you need to be worried about.  Eventually you do.  But first, the pipes will freeze.  Pex is quite flexible and can expand to a couple times its size before it will break.  But, the fittings, elbow's, valves, etc, will crack if they freeze. 

My permanent solution to eliminate any concerns will probably be to get 12v heating pads or heating tape, and put it along the pipes.  Wire it to a switch. Turn it on when needed.  You could get fancy w/ a thermostat to turn it on automatically. 

[Wallowa]

Good discussion...but we are at a point of beating a dead horse...I will only add this and then wait hopefully

for a viable means of safely keeping water in the FWC system at even below zero temps.  Fingers crossed!

 

Rondo...yes you are correct water in river was "very close to freezing"...28*F and yes "air was well below freezing"...so moving water freezes at below 32*F.  Distilled water also freezes at 32*F.

 

I concur that leaving a faucet dripping can introduce water from underground pipes that is above freezing.  Don't understand "it is that the open faucet prevents the pressure in the pipe building up and bursting the pipe when the water does freeze and expand"...if faucet was dripping and water in pipe freezes, faucet is no longer dripping so how can a none dripping faucet prevent pressure in a pipe?  Ice has the lowest density and maximum volume at 32*F when it freezes [floating ice cubes]; why pipes rapidly frozen can burst when defrosting and reaching max volume...long time since chemistry and physics so my assumptions as always may be wrong...  

 

Wicked...good ideas depending on how low the water system temps go for how long [factor in electrical and/or propane needed for any heating].  When marginal [crap shoot conditions], I use thermal mass of the 6 gallons of heated water; either in tank or if room, dumped into main tank and then reheated.   I leave on overnight but not while driving [propane].  Trouble there is as you pointed out that is in keeping pipes from freezing not main tank.  Crazy but I also have a last chance ploy of using 24 hour large hot pockets dispersed inside the cabinets on plumbing..

 

Still if there is doubt about the system freezing and flooding my Hawk...then there is no doubt... I drain it.

 

Out Here and thanks for the ideas...Phil

Edited by Wallowa, 23 January 2022 - 11:51 PM.