RV Surplus 
 Amazon's RV Store 

Notice: This page may contain advertisements. Click on the disclaimer for details.

Winterizing the Beast... er, RV.

If you live in the northern climates (or it seems as though these days, the south as well), sooner or later, you will need to winterize your RV. You can always take it in for this at your dealership, however, their schedule may not coincide with mother nature, and you could get caught with having to contend with freezing weather in a non-winterized RV. Wouldn't it be easir to just know how to do it yourself?

These days, in a RV - winterization is primarily taking care of the water system; although, a few other tasks are also required.

For my motorhome, the manufacturer has graciously provided a few engineering drawings for the asking. These drawings show the location of the structural members in the exterior walls and roof. If you can get them, this is where you start your research.

Oddly though, it is puzzling why you even need to winterize your RV's water system, as ANSI/NFPA 1192 (Standard on Recreational Vehicles) section states; The water distribution system shall be protected from freeze damage by one of the following:
  1. Designed and installed for gravity drainage or
  2. Constructed of materials identified as not being susceptable to freeze damage

And since the Recreational Vehicle Industry Association (RVIA) states that one provision of compliance to their certification is compliance with ANSI/NFPE 1192, then by proxy, if your RV has the RVIA symbol (near the main enterance door), then it should have this characteristic and not need winterization at all.

However, only a foolish RV'er would not winterize their coaches. In fact, many RV's also have an (Pink) RV Antifreeze injection point, and recommend protection with antifreeze. So what gives? Well, I'll let you make your own conclusion about that; so getting back to the topic of winterization...


Winterizing the water system.


There are basically four segments of this job; first - draining the hot water tank; second - draining the fresh water tank; third - blowing and/or pouring (pink) RV Antifreeze into the water lines; and fourth - treating the "p" traps.

Pre-winterization tasks: Prior to starting the winterization process, make sure you dump out and clean your Black and Grey Water holding tanks, and make sure you turn off the hot water heater - and wait at least 8 hours for the water to cool down.


Task 1: draining the hot water tank

To drain the hot water tank (after ensuring the tank's water temperature is not elevated), simply remove the drain plug from the lower side of the tank (lower circle in the photo to the right). Then, release the water pressure overflow valve if you wish, which is located near the top of the wter heater (upper circle in the photo), which will aid in draining the tank.

Some water tank models may have a sacrificial anode in the lower plug, which is used to combat corrosion. Inspect the anode at this time. If it is time to replace it, remind yourself to buy one prior to next year's spring commissioning.

When the tank is empty, close the vent at the top, but leave the plug at the bottom off. Store it in the bottom of the water heater so you can find it when returning the water heater to service.


Next, put the water heater into "Winterization Bypass" by rotating the three valves on the back of the tank into their opposite positions.

In the photo, the center valve is the cross-over valve, while the top and bottom valves are the hot and cold water supply valves.

Some units may have two valves rather than three, and other units may not have a winterization bypass at all.



The center (cross-over) valve should always be in the opposite position as the valves in both hot and cold water lines. For example, if the hot and cold water lines are open, the cross-over valve should be closed; and vice versa.


To illustrate what the winterization bypass does, refer to the drawing below. In the normal position (hot and cold water valves open and cross-over valve closed), the hot water tank fills from the cold water inlet, and hot water is dispensed via the hot water outlet.

However, when the tank is in the winterization bypass position (hot and cold water valves closed and cross-over valve open), the water tank is effectively disconnected from the water system, and the cold and hot water lines are tied together (which also allows you to winterize the hot water line from a single point on the cold water line).


Sorry for the watermark - but other people have been stealing this graphic.


Typically, you can identify when valves are opened or closed as the valve handle will always be in-line with the water flow. As shown below, when the valve handle is in-line with the water line, the valve is open, but when it is perpendicular, the valve is closed. This is not quite as apparent with the Right-Angle valves (90 Deg elbow), but you should still be able to identify which position is in-line.





Last reviewed and/or updated May 10, 2017