Best practice to clear water lines for winter use

[suburbancowboy]

I was at the cabin this weekend putting in the pex water lines in at the cabin.  I am now thinking about what is the best way to keep the water lines cleared out in the winter.  The two ways that I have come up with and talking with the inspector is to
1. design the system to drain with a gravity feed.  Cons - There will always be small places where water will pool and the system will be unusable until the small areas thaw. 
2. blow the lines out using air pressure.

Question for all of you how do you freeze proof you pipes?  If you use air pressure how do you blow it out and what type of connection do you use?

[ScottA]

Blow them out with air. Make sure you have way to get them all including the main line comming in.

[rick91351]

You still need to antifreeze all the traps and toilets.  RV antifreeze is pretty cheap and is on sale about now every year.  I pick up several gallons for the fifthwheel because we winterize it several times in the winter.

I would put a by pass on the hot water heater and plumb the drain in to a low point sump of some type.  Just open the valve on it and let it drain.  Or hook a garden hose to it and run it out the door.   

[JRR]

Do a normal water "dump" of the system at the drain valve.  After draining, place a clean catch vessel under the open drain valve.  Now pour in RV anti-freeze at each wash-basin or floor drain, enough so that you get ample collection sample into the collection vessel each time.  (Best done with an assistant, who can dump the drainage until anti-freeze rich.)  Gather and store the drainage for re-cycling next year.  Test the drainage for freeze protection temperature ... this should be the worst-case condition.

Each low spot and trap should now be protected ... and you have not spent a lot of effort.  Each year you may have to add some fresh anti-freeze to the process to get desired protection.

[ScottA]

The cheap easy alternative to anti-freeze is to use a shop vac to suck the traps dry but then you get the stink back into the cabin unless you plug the drains. This can be done by stuffing a rag in the toilet and closing the stoppers in the sinks.

[MountainDon]

Drains; like Scott said, vacuum but then pour RV antifreeze in. No dilution that way with the water in the drain trap.

Supply lines. Plumb it so it's easy to disconnect at the main incoming line and then hook a compressor up. Or make the system with an air inlet as a permanent item. Use an air tank fill valve.

[suburbancowboy]

Thanks for the suggestions.  I will need to pressurize the fresh water line for the inspection so I will incorporate that into the design to flush the system out.  For the drain system I will use rv anti freeze.

[NM_Shooter]

I'm not sure what the official word is on PEX freezing, but I ran tests with PEX loops and brass fittings, and they remained un-damaged through multiple freeze cycles. 

Ditto on antifreeze in the traps!

[Alan Gage]

I'm not sure what the official word is on PEX freezing, but I ran tests with PEX loops and brass fittings, and they remained un-damaged through multiple freeze cycles. 

I believe Pex "A" is supposed to be impervious to freezing (has some "expandability" built in). I've had Pex "B" freeze a few times with no problems though. I ran A in my current build for peace of mind and because it's got a bit more flexibility.

Alan