Winterizing question

[Antman]

Ok- just a general question.

I read all the articles and threads out there about using compressed air and /or RV antifreeze to winterize the plumbing. My question is this-

In your residential home you can just turn the water off and leave the outside hose faucets open during the winter. The water freezes / expands and doesn’t break the pipe because it has a place to go (out the faucet nozzle).

Why doesn’t this apply to the RV world? If all the faucets are left open the pipes should be fine, right? The drains I could see with the antifreeze but I don’t get all the hoopla for the pipes.

Can somebody enlighten me? Thanks!

[Houndbb]

In a house, you have long runs of pipe between connectors. In a trailer, you have shorter runs of... (insert soft hose, pex if you’re lucky) with many frequent (dubious) connections. As someone here put it, “Too many tiny spots for water to hide, freeze, and weaken the system”. Even in a house, depending upon the pitch of the runs, you may still have some problems.

[huntr70]

Your outside faucets don't necessarily work that way in your home.

Most have a drain back feature to get the water away from where it can freeze (back inside your home).

It also isn't going to lay in valves that are subject to the same freezing temps as outside. Unless, of course you keep your home at under 32 degrees.....

[sande005]

In many cases (but of course not all) freezing damage comes from air, not the water directly. Air in the pipes gets trapped. The water freezes, and as it expands it compresses the air, sometimes to very high pressures. That pressure spot ruptures the pipe. Of course, same can happen to a plugged pipe, fully full of water. As another example - in my boat, I had some water in the bilge. Submerged in it was the pump for the live well. The outside water froze first, being on the outside. Then the water inside the pump froze. No place for the pressure to easily go, so it cracked the pump housing, before finally also causing the encapsulating ice to crack and shift. I found that out when the boat took on water the next spring after running the live well pump for a while......
In your scenario, it depends on a) an inside valve being off, so you can open the outside spigot and b) some amount of air/water now in the inside pipe between the valve and the spigot and c) freezing first at or near the spigot. On the spigot side of the freeze point, the water/ice pushes to the outside. On the inside side, it pushes and compresses the water/air in the line. If the run is of sufficient length, the overall pressure increase is low enough for it to handle. If it is very short - the pipe breaks. Hence why the inside shutoff is usually a bit of a ways from the outside spigot.
In an unheated home, just like an RV, you can get many different spots that freeze before others - giving the subsequent pressure no place to go. Cabin owners here in Minn. learned that lesson a long time ago. You can't just open all the taps, and expect things to be just fine.
With the blowout method, you work to get as much water out as you can, and greatly increase the amount of air to compress, to minimize the pressure build up any remaining water can introduce into the system, if two or more ice plugs do form. With the antifreeze method, you introduce a liquid that does not (or very minimally) expand when it gets very cold.

[geotex1]

In good spirit, I chuckled aloud when I read the OP's post. If you never lived somewhere with real cold, real winters, you have such questions... I have worked projects in the mines of Siberia, been in Yellowknife mid-winter, and in a hamlet in Germany where snowfall was forecasted by the meter! I also 'suffered' Orange County winter! It's all perspective and relative to where you are.

Prior to moving into the PA mountains, my winterization was done by blowout, leave all faucets and low points open and 1 gallon of antifreeze to fill all the traps. Winter's worse at our corner home never damaged anything.

Then we moved here, in the Winter at that. I had already done the usual winterizing at our old home months before. Just towed up and parked our former Heritage Glen for the rest of the Winter. Winters here have weeks deeply below freezing and painfully frigid wind, and that first Winter had snow that put a drift as tall at the kitchen window against the camper! Come the Spring's opening, I found myself with a cracked head on the water pump, a cracked toilet flush valve, a cracked Oxygenics shower head - all tight spots where water was trapped, froze, and expanded. Only takes a few drops to expanded enough to break a plastic threaded connection, thin plastic housing, and crack the passage in a pump head!

That was about $150 in replacement as DIY, which buys a lot of antifreeze! Our new Solitude took me 4 gallons making sure to flush through the washer hookups and both exterior faucets in addition to the kitchen, double lavatory, toilet and shower faucets. $12 of antifreeze at my local ACE. I actually winterized twice this year because we had an unexpected cold snap a few weeks before our last trip so I dewinterized at the campground and rewinterized when we broke camp.

[sande005]

It's even more fun when a drain line in your house freezes, cracking a fitting in the wall. $10,000 later, and all this past summer dealing with contractors, it is fixed. Geez - a drain line, that for over 99% of the time just has air in it! But -30F will do its work pretty fast!

[Bungy]

Trust me, pipes in a house can freeze and burst even with all the taps open if it gets cold enough (-30C), don’t ask me how I know! Pex and poly b are a little more forgiving than copper but not by much.

[Akfiredog377]

I always blow my system out with compressed air then use antifreeze. Living in Maine I have seen temps as low as -20. When I was in Alaska we could see -50 to -60 easy. I winterized my TT the same way when I lived up there. Never once did I have a problem with the winter busting anything in my rig. I does not take too much to do and will save you money in the long run.

When you decide to wake up the camper in spring, flushing out the system is easy. I just run fresh water through the system to clean out the antifreeze then add bleach water to the fresh water tank and run that through the system. Let it sit between 24-48 hours. Drain/flush and you are good to go.

[Recharge]

I have just used air on all my trailers to blow out lines only and antifreeze in traps. I never had an issue and have had temperatures to -30c