Winterizing - Extreme cold winters

time2roll wrote:

Kayteg1 wrote:
Compressors are inefficient.
Get shop vac and let it run for 1 or 2 hr to blow the piping dry

Ever vacuum the water out?

Not from an RV, but I do have a good friend who uses a shop vac to winterize their cabin, vacuuming out the excess water from the toilet tanks and bowls before putting antifreeze in.

Growing up we had an apartment above our garage that would get winterized, and we used a plunger to get as much water as possible out of the toilet traps, but the vacuum is quicker and easier and more thorough for that. Of course, in a standard RV toilet, this is not something that needs doing.

For the supply pipes, though, it's not at all necessary to get every last molecule of water out. A few drops remaining don't cause problems, in my actual experience. Blowing out the lines doesn't need to take hours to be effective. (Of course, displacing water with antifreeze is also effective.)

I don't know if most shop vacs would develop enough pressure to push the water out or not, though if used in suction they should be sufficient in my estimation. Rigging up an adapter from vacuum cleaner hose to water inlet or low point drain seems to me like it would be a bit tricky.

We are in Northern Vermont and I just winterized this morning. I elected to use RV antifreeze but in the past I have used both methods, blowing the water out and using RV antifreeze. Both methods worked well.

If you unsure which method you want to use, do both. Blow out the lines, then fill the lines with antifreeze.

Kayteg1 wrote:
Compressors are inefficient.
Get shop vac and let it run for 1 or 2 hr to blow the piping dry

Ever vacuum the water out?

Use the compressor, it will do a fine job. I've never had a freeze related problem do so.
FWIW, freezing is freezing so your standard winterizing procedure will work fine.

Compressors are inefficient.
Get shop vac and let it run for 1 or 2 hr to blow the piping dry

Flapper wrote:

BTW - most bursting of pipes is due to air trapped between areas freezing water (or water and closed valves), not the ice itself. As the ice expands, the trapped air rises in pressure, to the point where the pipe or fittings give way.

I'm no expert, but wouldn't it be more likely to be trapped liquid water than trapped air? The change in volume required to compress air to a pressure that would burst the pipe would have to be quite large; it would have to be squeezed into something like an eighth of the volume to increase the pressure from atmospheric pressure (ca. 14 psi) to 100 psi over atmospheric pressure and so apply a 100 psi force to the plumbing. (This is a pretty straightforward application of the ideal gas law.)

Liquid water, on the other hand, is essentially incompressible.

swimmer_spe wrote:
So, I am ready to winterize my trailer's water system. I have a nice full brass fitting, an air compressor that can be adjusted for 30psi, and an air line.

Now, I know some of you know how to do this, but do you know how to do it for 'extreme' cold winters? We regularly get -30C(-20F) and colder.

For those who have those extreme temperatures over the winter, do you use antifreeze? How?

Here in Minnesota (-30!): I blow out all the lines with the compressor. Then I set the water heater valves to the by-pass position, and leave the big drain plug out for the winter. My water pump has a winterizing inlet tube and a couple of valves to change so the pump sucks from the tube rather than from the water tank. Stick the tube into a jug of antifreeze, turn on the pump, and then run all the taps, showers (in and out), low point drains, etc. until antifreeze comes out. Usually takes about a gallon and 1/2. The rest I pour into toilet and traps.
While just blowing out all the lines is probably pretty sufficient, I think this is one area where a belt and suspenders approach is warranted.

BTW - most bursting of pipes is due to air trapped between areas freezing water (or water and closed valves), not the ice itself. As the ice expands, the trapped air rises in pressure, to the point where the pipe or fittings give way.

As sound guy said, winterized is winterized. Here in Vermont we often have cold snaps around -20F (though it's not as cold as you are on the whole, I think). I blow the lines out with a compressor and put antifreeze down the drain traps and that's plenty sufficient; air doesn't freeze and expand.

I do, of course, also bring in any containers of water-based stuff like various cleaners or cans of food. Some of them may not actually freeze due to things dissolved in the water base depressing the freezing point, but I prefer not to find out which ones those are and which other ones do freeze the hard way.

Water expands when it freezes. After it's frozen, when it gets colder it contracts just like most materials. Colder than freezing doesn't make things worse.

swimmer_spe wrote:
So, I am ready to winterize my trail;)er's water system. I have a nice full brass fitting, an air compressor that can be adjusted for 30psi, and an air line.

Now, I know some of you know how to do this, but do you know how to do it for 'extreme' cold winters? We regularly get -30C(-20F) and colder.

For those who have those extreme temperatures over the winter, do you use antifreeze? How?

Not sure what "extreme" temperatures over the winter have to do with this? :h Freezing is freezing so any sustained temps below 0C and water is going to freeze eventually. Some gravity drain and add antifreeze, some blow only, some do both, but you'll never get agreement on which is "best". Do what suits you.