31 below zero, RV antifreeze failed?

While some types of RV anti-freeze are better than others, most will turn to slush or freeze at extreme temps. It should not expand, cause any damage. I normally open low point drains, after using anti-freeze in Fall, and blow most out. It will be mostly pure, so I dump the small bucket of used AF down the toilet, to keep some liquid in black tank.

You should be fine come Spring, when you flush your system.

Yeah, the trick here is that it doesn't expand and break things when it freezes. Assuming you got all the water out before you put the antifreeze in, your rig shouldn't be damaged. Water is actually unusual in that unlike most things, it doesn't shrink when freezing, it expands, which is what breaks things.

Once you drain and blow things out, you will probably want to put some antifreeze down drains to protect from freezing of the water in P-traps (won't drain or blow out).

Well I guess I got caught off guard with it being a solid.  No the frozen jug is not bulging.  I had never looked in past years and it was always fine in the spring.  I am going to build a small air flush out of an old small compressed air tank. I will put a regulator and ball valve on it for a low pressure push. I had thought about this before because I don't like how long it takes to get the left over smell out.  I have a detailed winterization process. Draining the fresh into a tub to toss outside, filling P traps, faucets open etc. It is a great camper in like new condition. I just want to keep it that way.  I appreciate the responses.  You never stop learning.

I use rv antifreeze, but I don't really trust it to get into every inch of pipe, valves, etc in our Lance.  Its going down to 5 degf here tonight in Alabama and I will have the camper heat running to keep the camper about 55 degf.  Probably overkill but its cheap insurance and I will sleep well. 🙂

I did a couple of tests a few years back by putting a cup of rv antifreeze in our freezer.  IIRC it went down to about -2 degf.  The antifreeze turned to slush, but never froze solid.

bradw

After using the antifreeze and having it turn to slush, in the following years I would blow it out of the lines using compressed air after adding it to all lines. You have to lower the pressure when doing this. Nothing left to freeze this way.

😁

I have been doing this for many years and we have had great results. Completely drain the water from your rv using the low point drains, then use the bypass to pump rv antifreeze into the lines, faucets etc. After that drain the rv antifreeze using the same process you did before. I catch the draining antifreeze and use it in my black tank for a little extra. No air compressor needed.

Following this procedure we have almost no (I said almost) smell, and it is easy to rinse the pink out of the system since there's not much left. I should add that I bypass the water heater first and never put any rv antifreeze in the fresh tank. It makes it very easy in the spring when I want to use the 5th wheel. My biggest concern for people that use air to blow out the lines is how do you flush the water pump?

My belief is that with not leaving the rv antifreeze in the lines all winter the smell doesn't get into the lines nearly as much. Plus the last thing in the lines was the antifreeze so even if it collects in a low spot nothing will get damaged. Trust me, with my luck there would be a plastic fitting that was the low spot and it would break! I do have pex lines, but the fittings aren't and I am not taking a chance with them. 😉

I work for a marine supplier. Had one of the places say they wanted X type of AF as it supposedly only turned to slush. So it would not damage the boats motors! Much more expensive than waterlines in RV's. They put a cup of both the stuff they preferred, and one that we sell about 100 to one vs what they wanted. The one sold the most, was actually softer than the one they wanted, and a bit cheaper too. 
At the end, both work well. Granted we only usually have temps in Puget Sound into the 20F relm, had a few pushing 5-10F around here in the last week.
Another buyer will only use -100 as they think it will protect them more from cracking motors. 
Reality, if the AF freezes per say, but does not expand, it is not an issue for anyone, whether you put it into an engine cooling system, or the water lines. 
Just make sure you use the types for waterlines that are not poisonous to you  or other animals if you dump it on the ground after use, or in the case of a trailer able boat motor, when you turn on the system in the water, it will not hurt the water you are in. 

Marty

Not to push where I work, but here is an online article that should help you understand the ratings a bit better. 
In a nutshell, the rating you use, ie -50, is what that version will burst a copper pipe at! BUT some will actually freeze at say 10-20F temp. So, what your gallons you have, have done, is normal! Froze, but have not expanded to burst your pipes!
The client I mentioned wanted the wintersafe, vs std -50. As you can see in the article, the wintersafe went solid before the std -50. Which is what the client found when he put some in their freezer! I work in the wholesale side of things. We sell 300-400 55 gal drums to various boat dealers getting them prepped for winter use. Ranger Tug buys this stuff to put in waterlines for boats leaving the area to other places from October to March. We ship 10-15 pallets with 4 drums per to a place in Alaska too.  
If you are near the WM in Spokane, they should be stocking the -50 or -100. Or it can be shipped to you next fall. The minus 100 might be a better option based on temps you are having from an additional safety standpoint. Our brand is made by Starbright, you might find places with that brand, or another companies version, made by starbright cheaper if you hunt around. At $5-8 per gal with a quick online search, shopping at multiple places will not save you a lot per say, if you only need a few gallons. A 55 gal drum might be another issue at $350-400+ per barrel! 
Here is a link to article, it's time to go to bed, did not realize it is so early in the AM! LOL

How to Choose Antifreeze for Your Boat Engine | West Marine

Marty

I have lived in Alaska for now going on 42 years....

As far as any type of antifreeze is concerned - I would tend to use my antifreeze tester to see what the TRUE concentration reading shows - mixing 65% Prestone antifreeze with 35% distilled water will actually show a different reading then using the same mixture 2/3rds antifreeze-1/3rd water with the Peak brand....just by looking at RV antifreeze itself with a label rated past -50 below F I laugh and say no -way ! as I lived in the arctic for too long - and I am a native southern Californian !

I never used any kind of RV antifreeze for my cabover for outside winter storage, as I simplify any RV life I ever get (only up to one month a year as I still am a working stiff) so I just never use the sink or toilet to begin with - as I purchased a portable toilet for the girls, and use my own honey bucket with a lid and a removable toilet seat to boot along with using a couple of Prestone jugs for #1 nature calls if I am not in the wilderness or a nearby rest stop or bathroom facility.