Winterizing a Trailer Procedure

mike-s wrote:
Not sure where you get that 1/4" as a requirement, or even typical. If you look at made-for-purpose RV blow-out plugs, the brass ones have an orifice much smaller than 1/4", and others have Schrader valves which also very much restrict flow.

It would be a very large RV to have more than a couple of gallons of capacity in the water lines. I know a single gallon will fill the lines on our (relatively modest) one with more than enough left to fill the traps. It's more volume than pressure that's needed to blow out lines - you really only need a few psi to push the water through. A 2 gallon air tank at 40 psi will deliver over 3 gallons of 10 psi air.

And really, you don't even need that - just constant flow. Open the valves one at a time starting closest to the source. After you get rid of all the constant water flow (so they just sputter), let the system pressurize, then go back and open one at a time, the air pressure in the lines will blast out most of what remains.

A 1/4" is the standard ID of an air fitting like a Milton quick connect. The effective ID of a Schrader valve is 0.21" so the difference really isn't worth talking about.

Your point about volume was exactly what I was getting at, let's says a typical RV has 20' of 1/2" pipe in each of hot and cold circuits. A 1/2" pipe has a volume of 0.0102 gallons per foot, so 20' of pipe would hold 0.204 gallons. Now hook up a tankless (battery powered tire filler?) to it and charge it to 40 psi.

When you open the tap you have 2/10ths of a gallon of air trying to displace the water before the pressure drops back to zero.

That won't do very much if anything.

Pressure ONLY counts when there's a solid plug of water ahead of the air, once there's even a tiny way past that water air takes the path of least resistance.

It is only continuous air flow at that 40 psi that drags all those remaining drops along and out the tap.

Moved to Tech Issues forum from DIY.

JaxDad wrote:

garyemunson wrote:
The best tool to own is a battery powered compressor with a regulator you can set at 40 lbs.

In theory, a 1/4" air fitting running wide open, like when blowing out a water system, with the feed pressure at 40 psi will flow a little over 25 CFM.

A decent small 120 volt compressor with a 2 gallon tank might be able to make 5 or 6 CFM at 40 psi.

The only way you'd get enough volume of air with a battery powered compressor would be to fit an air tank inline with the hose and create a reservoir of pressure to give you full pressure for a much longer period of time, however you'd likely burn up the compressor in no time doing that.

Not sure where you get that 1/4" as a requirement, or even typical. If you look at made-for-purpose RV blow-out plugs, the brass ones have an orifice much smaller than 1/4", and others have Schrader valves which also very much restrict flow.

It would be a very large RV to have more than a couple of gallons of capacity in the water lines. I know a single gallon will fill the lines on our (relatively modest) one with more than enough left to fill the traps. It's more volume than pressure that's needed to blow out lines - you really only need a few psi to push the water through. A 2 gallon air tank at 40 psi will deliver over 3 gallons of 10 psi air.

And really, you don't even need that - just constant flow. Open the valves one at a time starting closest to the source. After you get rid of all the constant water flow (so they just sputter), let the system pressurize, then go back and open one at a time, the air pressure in the lines will blast out most of what remains. Run the pump briefly with the supply valve closed and the antifreez line open to clear it. Then open all the valves and the low point drains and let the few remaining drips come out. Any left after that shouldn't be a worry, there will just be little bits here and there surrounded by enough air that there's room for freeze expansion.

garyemunson wrote:
The best tool to own is a battery powered compressor with a regulator you can set at 40 lbs.

With all due respect, that's VERY dangerous advice.

The pressure the air is under has very little to do with clearing the water out of the lines compared to the VOLUME of air you put through the system.

In theory, a 1/4" air fitting running wide open, like when blowing out a water system, with the feed pressure at 40 psi will flow a little over 25 CFM.

A decent small 120 volt compressor with a 2 gallon tank might be able to make 5 or 6 CFM at 40 psi.

The only way you'd get enough volume of air with a battery powered compressor would be to fit an air tank inline with the hose and create a reservoir of pressure to give you full pressure for a much longer period of time, however you'd likely burn up the compressor in no time doing that.

It would also take all day doing it that way.

don't forget the toilet water supply, showerheads and hoses, kitchen spray hose

mikestock wrote:


I do have a refrigerator ice maker that I have to disconnect ant blow all of the water from the lines. This, I would do anyway, as you never want to let that pink stuff get into your ice maker.

Besides being cheaper, I feel that this process is far easier than my old antifreeze method.

on my ice maker I just disconnected the input at the solenoid outside and put a standard 90 degree twist off fitting on the feed. treated it like any other fitting, just let the pink stuff flow. and I never did anything on the piping inside the freezer, I sort of assumed that that got below freezing normally. :)
bumpy

After spending many years winterizing with the pink stuff I bought a lightweight air compressor with a regulator that I could adjust to about 55 psi.

Now, I just empty the tanks and water heater, bypass the water heater, as usual, and hook up the air to the RV water inlet. Then, I just walk around opening each hot and cold valve (one at a time) and let the air run until the lines are each dry.

I do pour a little pink antifreeze into each drain trap and into the washing machine to pump it through the washer pump.

I do have a refrigerator ice maker that I have to disconnect ant blow all of the water from the lines. This, I would do anyway, as you never want to let that pink stuff get into your ice maker.

Besides being cheaper, I feel that this process is far easier than my old antifreeze method.

ScottG wrote:
I had AF turn to a slimey goo one year in my water system.
After that I just blew everything out. Works a lot better and faster and it's nice the next season not having the pink stuff foam everytime we run a faucet.
The only place I put AF is in the drains.

sounds to me like you put the AF in your fresh water tank. couldn't completely drain it. and slimy goo is pretty much what AF does when it "freezes", doesn't expand and bust things however.
bumpy

spend $15 for a winterizing kit if your rv doesn't already have one. a T that goes on before your water pump that can pull in antifreeze directly to the system. do NOT fill up your water tank with antifreeze. bypass and drain the water heater.
bumpy

I had AF turn to a slimey goo one year in my water system.
After that I just blew everything out. Works a lot better and faster and it's nice the next season not having the pink stuff foam everytime we run a faucet.
The only place I put AF is in the drains.