I used anti freeze in the first motorhome I had. the way the thing was built, I had to put 6 gallons of the stuff in the water tank, then pump it through the lines. Then, in the spring, even though I drained and flushed the tank twice, I had to put up with the flavor of the antifreeze for most of the summer.
Since then, I have used air almost exclusively. 60 PSI, through a Harbor Freight filter/drier.
It works. No problems.
Of course, here in SOUTH Central Montana I guess it really doesn't get all THAT cold. Last night it only got down to 8 below zero, measured on my hi/lo recording mercury thermometer.
I remembered to check the frig in the Soouthwind today. I had left a pint of home-canned peaches in there. Frozen solid. there was also about a third of a bottle of Georgia wine in there. Yup, it also was frozen solid.
I wonder, those who insist anti-freeze is the ONLY way to go, how much of the stuff do you use to winterize your underground sprinkler system?
