Winterizing plumbing with no water?

[Dingfelder]

Do I still need to fear the plumbing somehow going wrong if there's no water in it in the first place?  I've never used the toilet, barely used only the kitchen sink, never the bathroom one, and long ago emptied out both the grey and black tanks(nothing, just the water from the demo that sold me the trailer), then later emptied them again just to be sure.

Is there some sneaky water hiding, maybe?  Or is a dry system safe pretty much by definition?

 

[reppans]

Dry is safe of course, but the problem is that so much of an RVs plumbing is hidden. If the demo water was sourced from the fresh water tank and pump through the lines to the faucets, then how do you know the lines are dry? Large areas, like the holding tanks, are generally safe with small amounts of water as the water has plenty of space to expand into when it freezes - it's the small confined areas in low spots in the system where water settles and risk freezing and breaking tubes, and especially plastic joints (I understand PEX tubing has some give).

Many use oil-less air compressor/tanks to blow the water through/out the system, but since the internal lines still left wet, there will always be some dribble back to settle in a low point. Water settling in an inch or so of tubing (or joint) is probably not going to be a problem with plenty of room to expand either direction, but water settling a foot of tubing might be a different issue if the ends freeze before the center.

The safest way to protect plumbing is pump pink RV antifreeze through all the lines, faucets, with some making it into the holding tanks, dump valves, and don't forget the P-traps.

 

[B and C]

You will also want to drain the hot water tank. Some RV's have a bypass setup at the H/W tank so you don't have to fill it with antifreeze (pink). Depending on which H/W heater you have there is either a petcock or you have to remove the anode to drain it. If you have the anode, now is a good time to replace it. They only last a year or two depending on how long they are immersed in water. After draining the tank, put the anode rod back in as the threads in the tank can rust and make installing it later a PITA. Oh, and use teflon tape on the threads.

I also leave all the faucet's in the on position. There is a plastic manifold where the hot and cold water mix before coming out the spout. A friend had all his manifolds crack and had to replace all the faucet assemblies. Not a fun or cheap job.

 

[tx2sturgis]

The 'P' or 'S' traps under the sinks can hold water too, they are usually plastic and some of them have a collar or plug that unscrews so you can empty or clean them.

 

[Dingfelder]

Many use oil-less air compressor/tanks to blow the water through/out the system, but since the internal lines still left wet, there will always be some dribble back to settle in a low point.  Water settling in an inch or so of tubing (or joint) is probably not going to be a problem with plenty of room to expand either direction, but water settling a foot of tubing might be a different issue if the ends freeze before the center.

The safest way to protect plumbing is pump pink RV antifreeze through all the lines, faucets, with some making it into the holding tanks, dump valves, and don't forget the P-traps.

Thanks for the info and ideas, everyone.

Blowing out the system definitely sounds like a good start.  Where would I get one of those oil-less air compressor tanks?  Rent one from Home Depot maybe?

 

[reppans]

Thanks for the info and ideas, everyone.

Blowing out the system definitely sounds like a good start.  Where would I get one of those oil-less air compressor tanks?  Rent one from Home Depot maybe?

You can buy 2gal tank oil-less compressors in the $50-80 range - just google it. I happened on a Black & Decker 2 gal clearance sale at Targets for $25 (bought like 4 for holiday gifts) and been using it for years for to winterize, and also for tires. You also need a valve adapter (air>water intake) sold at RV sites for a couple bucks.

It makes things very fast and easy, but I'm overly cautious and still followed it with antifreeze.

You may still need some antifreeze in the large tanks, through the dump valves, and P-traps, depending upon how well you can empty them (e.g. thru a clean-out valve) - air pressure only works through smaller tubing.

 

[highdesertranger]

paint compressors and breathing compressors are oil-less. I don't know if I would trust a rental paint compressor unit. If I owned it since it was new would be a different story but a rental I don't know. if you know someone with one maybe, the safest bet would be a hooka diving system you know that has good air. I would like to point out paint equipment isn't FDA approved for anything, breathing compressors are. highdesertranger

 

[Weight]

I would use any cheap diaphragm compressor. But you would be much better if using RV or Marine freshwater system antifreeze.

 

[reppans]

Not sure I'd go with any old diaphragm compressor - IMHO, you need the tank buffer for a substantial volume 'poof' of air to clear the line.. it's very much like clearing a snorkel. Slow/low volume air dribbling in risks bypassing more water.

A 1 gal tank would be fine, but 2-3 gals is more useful for not much more $$ to also handle vehicle tires

 

[maki2]

Or you can snake a long skinny tube in and connect it is a wet dry shop vac and suction the water out of traps and water heater tanks. Duct tape is your friend for making temporary connections.