Water in sink trap over winter.

[WFD]

Originally Posted by 5picker

And to expand (pun intended) on the ice bursting pipes... even in an open pipe such as a P-Trap, the liquid will first freeze where the it contacts the pipe basically forming a frozen ice shell. Then as the liquid which is more towards the core freezes, it expands and pushes on the outer already frozen liquid to the point it can burst pipes.

In a holding tank or other container where a large surface of the liquid isn't confined, as the liquid freezes, it simply expands with no issues. (think ice tray in your refrigerator)

But if I put my ice tray in the refrigerator, I have nothing to worry about because it won't freeze! Just sayin'!

[tomkatb]

How did you winterize the rv?

What you have likely will freeze in the traps. We use air to winterize. That and a half gallon of antifreeze.

When done open the gray tanks and drain the residue into a bucket and pour it somewhere ok. Gray water plus antifreeze is pretty harmless. A gallon in the gray tank might be ok. I would dump it. Easy.

[TowPro]

Originally Posted by Larry-NC

Also, another thing that's forgotten is the city water inlet, especially if you winterized by pumping antifreeze through the system. Same setup but go to the city water inlet, remove the hose, pry out the domed screen, STAND TO ONE SIDE, and press the little plastic stem until antifreeze is emitted. Same thing with outdoor shower if you have it. And as stated, hold the flusher on the toilet until you see pink stuff.

when you do this there is very good chance you will destroy this check valve, there is an o-ring that gets dislodged and you can't get to it without taking plastic valve apart.


I always used an adapter I made that would fit onto my outside shower. this adapter replaced the shower head with a male hose fitting that fit the fresh water inlet.


Last thing I would do winterizing is to force antifreeze through the outside shower to both the fresh inlet (also switch valve to fill fresh tank so you get a little antifreeze in that line as well) plus last but not least send some antifreeze through your black water flush system.

[jacques1543]

Absolutely go back and add antifreeze!!!

[RobertDS]

Originally Posted by Nodnerb

Hi all. Ok so I made a stupid mistake closing our seasonal trailer for the season. I had some water in the kitchen sink for rinsing hands while closing up. When all was done I simply let the water down the drain and left without also running some antifreeze into the sink. I was almost home before I realized I forgot. So what do ye all say? Do I need to go back to put some antifreeze in that sink trap or will it be ok and have room to expand since it is just the drain and not a "sealed" system like the supply lines?

Thanks.
Brendon.

I did this last winter. I realized that even though my wife and I had done all of the drains (i.e. shower, toilet and bathroom sink) but not the kitchen after we had traveled 900 miles. Yep, I worried all winter. I came back prepared to redo the kitchen sink.

I was lucky. I am guessing the double open ended pipe saved me.

This winter will be different. I say absentmindedly.

[Comanchecreek]

Make sure you pour enough down the drain to displace any water also left in your grey tank. The valves are usually at the low point and frozen water can crack the fittings and the tank at those low points. Displacing all water in the system is key to preventing plumbing problems. Do that with all of your holding tanks.

[Iwritecode]

Originally Posted by Comanchecreek

Make sure you pour enough down the drain to displace any water also left in your grey tank. The valves are usually at the low point and frozen water can crack the fittings and the tank at those low points. Displacing all water in the system is key to preventing plumbing problems. Do that with all of your holding tanks.

Or just drain them.

[TitanMike]

Originally Posted by Comanchecreek

Make sure you pour enough down the drain to displace any water also left in your grey tank. The valves are usually at the low point and frozen water can crack the fittings and the tank at those low points. Displacing all water in the system is key to preventing plumbing problems. Do that with all of your holding tanks.

One can also do as Hot Tub manufacturers recommend when winterizing. Use the exhaust port on a shop vac and blow water in p-trap "down the drain". Then just close the strainer/stopper to prevent any smell that might intrude from the piping.

BTW an electric leaf blower does a great job too.

[Dirthawg_]

Has anyone here had a P trap freeze as a result of leaving untreated water in the trap?

The reason I ask is I don't believe a pipe will burst if it not under pressure and has two open ends that will allow the freezing water to expand.

In the past I used to winterize my trailer by blowing air through the city water connection. I never once attempted to clean or treat the p traps. Over the course of 3 winters that regularly dropped into the teens for a week or more I never had an issue with broken plumbing.

If water freezes in all directions regardless if there are 2 open ends or not that allow for expansion then ice cube trays would be splitting at every use.

Maybe someone that would like to prove that theory should fill a p trap with water and place it in the freezer at -20 for the winter and see what happens. I'm betting it will survive without any trouble.

[Larry-NC]

Originally Posted by Dirthawg_

Has anyone here had a P trap freeze as a result of leaving untreated water in the trap?

The reason I ask is I don't believe a pipe will burst if it not under pressure and has two open ends that will allow the freezing water to expand.

In the past I used to winterize my trailer by blowing air through the city water connection. I never once attempted to clean or treat the p traps. Over the course of 3 winters that regularly dropped into the teens for a week or more I never had an issue with broken plumbing.

If water freezes in all directions regardless if there are 2 open ends or not that allow for expansion then ice cube trays would be splitting at every use.

Maybe someone that would like to prove that theory should fill a p trap with water and place it in the freezer at -20 for the winter and see what happens. I'm betting it will survive without any trouble.

I never deliberately put anti-freeze in the P-traps, but I do run the taps until they're solid pink, so some antifreeze certainly gets in.

But I also let the dehumidifier run in the winter, sitting in the shower, and I don't seem to have lost a trap there, either. I suspect the antifreeze in the trap is pretty dilute towards the end of winter.

But I volunteer to step up. I've got a spare P-trap here, and a chest freezer that's set quite cold (very hard to dip ice cream from it). I was about to fill the P-trap and prop it up in the freezer, when I realized mine is PVC. I should really do this with an ABS trap to be fair. I've just ordered this one: https://www.amazon.com/U5895-HXH-P-T...3981570&sr=8-2
and it will be here Sunday.
I will prop it upright and fill it with water and leave it for a few days. Remind me to report the results.

[Dirthawg_]

Originally Posted by Larry-NC

But I volunteer to step up. I've got a spare P-trap here, and a chest freezer that's set quite cold (very hard to dip ice cream from it). I was about to fill the P-trap and prop it up in the freezer, when I realized mine is PVC. I should really do this with an ABS trap to be fair. I've just ordered this one: https://www.amazon.com/U5895-HXH-P-T...3981570&sr=8-2
and it will be here Sunday.
I will prop it upright and fill it with water and leave it for a few days. Remind me to report the results.

Right on! I look forward to your results.

[TheMarkles]

Glad I saw this thread. Did the antifreeze winterization and never gave the city water inlet a second thought, thanks Larry!

[Larry-NC]

Originally Posted by Comanchecreek

Make sure you pour enough down the drain to displace any water also left in your grey tank. The valves are usually at the low point and frozen water can crack the fittings and the tank at those low points. Displacing all water in the system is key to preventing plumbing problems. Do that with all of your holding tanks.

Or simply leave the gray tank valve open all winter, and the cap off.

We leave a dehumidifier running in the shower all winter. One year we left the gray tank valve closed and I had to replace a couple of pieces of ABS piping at the valve in the spring. Since then I've left the gray tank valve open and connected a sturdy HDPE sewage tote to collect the outflow.

[Larry-NC]

Originally Posted by Mr. Dan

If one pays attention, one can learn something every day: “it is the process of water changing to ice that causes expansion and the bursting of pipes.”

True. If I remember my Physics correctly, water is at its maximum expansion at 4°C, or about 7°F.

[Larry-NC]

Originally Posted by Dirthawg_

Right on! I look forward to your results.

Test started at 1648 today. The wood props are not tight against the traps.

[Larry-NC]

Originally Posted by Larry-NC

Test started at 1648 today. The wood props are not tight against the traps.

The trap was frozen solid when I checked the next day, but I've been busy and just left it in the freezer until DW had me to defrost the freezer a day or two ago.

The answer is the trap did not break. We can conclude that a trap--even a brittle ABS trap--does not break when filled with water in the normal orientation. I had it as full as possible, in the same position as it would be in actual use.

[Dirthawg_]

Originally Posted by Larry-NC

The trap was frozen solid when I checked the next day, but I've been busy and just left it in the freezer until DW had me to defrost the freezer a day or two ago.

The answer is the trap did not break. We can conclude that a trap--even a brittle ABS trap--does not break when filled with water in the normal orientation. I had it as full as possible, in the same position as it would be in actual use.

Thank you Larry for taking the time to do this experiment. The outcome was exactly what I expected.

[Comanchecreek]

The cracking happens usually as the ice thaws, not while it is frozen solid. Also, are those regular traps for a house? Might be somewhat heavier walled than those used in your RV application.

[Larry-NC]

Originally Posted by Comanchecreek

The cracking happens usually as the ice thaws, not while it is frozen solid. Also, are those regular traps for a house? Might be somewhat heavier walled than those used in your RV application.

The trap was not cracked after thawing.

Residential traps are PVC, white or cream colored. This is a standard ABS trap as used in RVs. If you like, I can measure wall-thickness with a micrometer.

[Aussieguy]

thawing incorrectly by adding heat can cause problems


natural thawing is pretty safe
plastic ... can become brittle when frozen.. let it thaw slowly and don't try to dislodge ice by hitting it