Originally Posted by Yosemite77
I have family south of you, and winter was a huge deal for a time last winter. In short, just leaving the lines open wouldn’t work. Keep in mind that you most likely have cheap plastic PEX fittings, which would easily crack as the ice expands.
RV antifreeze is cheap compared to repairing water damage. Winterizing really doesn’t take much time. Skipping it isn’t worth the downside.
PEX tubing is freeze resistant. It is unlikely to burst.
Valves, faucets, fittings, flexible connecting lines, and pumps are often not so resilient. P traps, drain pipe, waste dump gate valves are also vulnerable.
Ice makers in refrigerators and clothes washers are a serious issue. Black tank spray systems can be a problem. Fresh water and waste holding tanks are not a problem if drained. There will be residual water in them, but that will not be a problem.
Water heaters must be drained or filled and turned "on".
Low point drain systems:
In the old days, opening faucets and low point drains worked except for pumps. Extra effort to get water out of pumps was necessary. Certain other spots needed special consideration.
Today, RV plumbing designs are more complicated. It is hard to be sure no pockets of trapped water are present when draining.
Use RV antifreeze pumped through the 12 volt pump. Put antifreeze in P traps. Drained tanks are not a problem. Waste gate valves will be OK if you do not try to operate them while frozen. Follow one of the many published procedures.
Diluted RV antifreeze will not protect anything, so residual water in tanks will usually prevent RV antifreeze from protecting waste gate valves. Don't try to operate them when frozen. Leaving gate valves open prevents problems with drain pipes. However, open gate valves can be inviting to rodents looking for winter quarters.
Black tank spray systems probably need RV antifreeze. The "city" water fitting has a check valve in it. Many can be flushed by pressing on the check valve from the outside until pink shows.
More complicated plumbing systems on motor homes and motor coaches may have special requirements. See owner's manuals.
Blow out method:
I have very little experience with the blow out method. These points should be considered.
Any trapped water will freeze and expand. Frozen water by itself is not a problem. Trapped frozen water will expand and burst the container.
Blow out must have enough air volume while blowing that water is removed. A trickle of air may not succeed. Every where there is water must be considered.
Blow out method is a good one for frequent winter trips and in desert environments. The system does not need to be flushed when adding water.
Follow one of the published procedures.
Using both blow out and RV antifreeze is like wearing both suspenders and a belt. Each is usually adequate by itself. But there is always that unlikely scenario where two methods avoids a problem. What is the cost of failure? I don't do both.