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Winterization 101

Part 1

This is not the be-all/end-all on winterizing your RV but it is a start for you.

Let’s talk about what needs winterized:

  • Plumbing
  • Faucets, sinks, shower (both inside and outside)
  • Water pump
  • Washing Machine
  • Ice Maker
  • Dishwasher
  • Black/Grey/Galley Tanks

First up a controversial topic:

Air vs Anti-freeze.

This is the beginnings of a Holy War, we here at Mobile RV Repairs do NOT recommend using air to winterize and here is why:

  • Say you are using an air tank, what pressure are you using to send air through the lines to flush out the water.
  • What exactly is in the tank, rust, bacteria, who knows what else that now you are going to put into your water lines.

For us it is a hard NO when it comes to air winterization. 

I can hear some of you already saying where is the comment box so you can rip me a new one, well there isn’t one, this is our stand and it is your RV, so you can do as you please.

What we do recommend is use the RV Anti-Freeze, the pink stuff.

DO NOT USE AUTOMOBILE ANTI-FREEZE, if you have done so in the past or bought a used RV where it was used, your safest thing is to have the entire plumbing system redone.  Do you really want to subject your body to the poison in automobile anti-freeze???

See below for an example of what we have been using for last 13 yrs winterizing our RV, the most important part is NOT who makes it but that it covers for -50 degrees fahrenheit.

Steps to do BEFORE you winterize

Find where your water pump is.  Look to see if there is a tube of some sorts of tube or acces water line that will let you get the RV anti-freeze into the system.  It could be somewhere a handle, lever, access point, it entirely depends on your RV.  In my Class C, there is a tube right next to the water pump. If you have an older RV (like my 1987 Mallard), it didn’t not have one, I had to install a bypass kit near the pump to let me pull in the RV anti-freeze.

Begin the draining of the water heater and all of your water lines.  Open at least one faucet, find the low point drain valves, open them to begin drainig water from lines and your freshwater tank, go to your water heater and remove the drain plug and let it drain.

Go to your favorite place to buy RV anti-freeze, most RVs don’t need more than 3-5 gallons, mine takes about 1.5 .  Keep in mind if done correctly that amount is for MOST all RVs (as long as you are not filling the water heater, which you shouldn’t be as we will talk about bypassing the water heater next.

Water Heater Bypass

There is no need to fill your water heater with anti-freeze, it is just a waste of time and money, so let’s see if you can find your bypass valves.  Now look around your RV on the outside to see where your water heater is, do you have an access panel, cabinet or someway to see the back end of your water heater from inside the RV, or maybe you have a simple valve where the rest of your water connections are to bypass the water heater.  This could be the time you break out your RV manuals to figure out where it is.  See an example below.  What you see here is a 3 valve bypass setup(there are RVs with a 2 valve, a one valve and no bypass systems but today were going to talk about the 3 valve system).  Cold water comes in the bottom, hot water comes out the top.  Bypass the water heater by turning 3 valves, right now that picture shows a confusing setup, so why did I show this picture for a couple of reasons, look closely.

All 3 valves are open, you can tell this by looking at the valve, if the ends are inline with the water lines, then it is open.  Now what happens if you have this setup this way for winterization?  The anti-freeze will go into the hot water tank.  The one at the opt and the bottom need to be turned 90 degrees so they are NOT inline with the water lines.  The one in the middle with the cold(blue) tubing on bottom and hot(red tubing) on top is in right position for bypass.

This might seem to confusing but think about it logically, if you want water to flow through the tube the handle need to be inline with the tube.

So for bypass make the top and bottom handles NOT inline with the water tubes, then when the anti-freeze is pumped in, it will not enter the bottom of the water tank but will go up the blue/red line with the valve in it and follow the hot water lines through the rest of the RV.


So do you know what happens if you leave the valves in this position when not in winterization mode, middle of summer?   Looking the current position of the handles, what happens is water enters the water heater, gets heated and comes out the top but since the bypass line is NOT turned off, the cold water again goes both directions up the bypass line AND into the water heater, mixes with the hot water coming out of the water heater and you get a lukewarm shower, blech.

So keep in mind bypass water heater the two valves(going to and coming from) for the water heater need to be turned NOT in direction of water flow and the bypass valve needs to be turned in direction of water flow.

When in non-winterized mode, the bypass line in the picture below the one going up and down, its handle needs to be NOT inline with the water line whereas the other two MUST be inline with the water line to allow cold water in and hot water out of the water heater.

So you should have your water heater on bypass, it is draining and your water lines(and freshwater tank) should all be draining also.

In the next post, we will talk about the water pump and how get the RV anti-freeze into the system.  Check out all of our services.


As always if this too much for you and you are in Ohio, feel free to contact us, we can do this for you, contact us via the services link above.