Originally Posted by KyDan
RV antifreeze is rated 50 BELOW.
Frig, up here -50 is a pretty brisk day eh.
The idea of the antifreeze expanding and bursting the filter canister is worrisome. Here is what Camco says about it on their website:
Q. What is the difference between freeze point and burst point of antifreezes?
A. The freeze point is the temperature of the solution where ice crystals will start to form in the solution and it will have difficulty flowing. This temperature is around +10° F with -50 RV Antifreeze. This temperature is not indicative of the winterizing protection. RVers need to be concerned about the burst protection. The burst point is the temperature where the solution will begin to expand and thus cause the pipes to burst. A unit winterized properly with -50 RV Antifreeze should show a freeze point of around +10° F, which indicates a burst protection of -50° F.
Q. How can I test the antifreeze in my plumbing system to make sure I have the proper burst protection?
A. The best assurance is to follow the instructions on the label and be careful to remove all the water from the system before winterizing to avoid dilution of the antifreeze. Camco offers an instrument called a refractometer which accurately reads both freeze point and burst point of the propylene glycol solution. This instrument is used in all of the Camco facilities to check the quality of our blends at the time of manufacture.
Q. I had some -50 RV Antifreeze stored in my garage and I noticed it was frozen. Is your product defective?
A. No. Propylene glycol antifreezes are designed to provide burst protection to temperatures of -50° F or below. Ice crystals will start to form in -50 RV Antifreeze at temperatures around +10° F and will appear to be solid ice at around -10° F to -15° F. Propylene glycol based antifreezes continue to contract and will not expand until temperatures of -50° F are reached, thus providing burst protection for pipes. If you need a product that flows at the lower temperatures, a higher concentrated product such as Winter Ban -100 or our Ban Frost Marine Engine Antifreeze should be used.
So, from that, unless you hit -50 there should be no expansion IF you got all the H2O out when you winterized. If not, according to Camco, the properties are dramatically altered, meaning you're screwed.