Steve Savage submitted this article to RVtravel.com when he was a Master Certified RV Technician with Mobility RV Service.
Every year folks ask me questions about winterizing, and every year I go through the same steps. I try to keep things as simple as possible, but some folks just seem to want to try doing things that do not work.
Here are the things that DO NOT work
1. It does not work to simply open faucets to allow for expansion. Opening a faucet does nothing to alleviate freezing in the faucet valve body, which is where freeze damage occurs.
2. It does not work to simply open low-point drains. Most low-point drains are virtually worthless in draining the system, unless you are using a compressor to force the water out through them.
3. It does not work to open cabinet doors and keep an electric heater going. In many RVs the furnace has to run to get heat to the water lines under the floor. An electric heater will protect what is above the floor, but not what is below the floor.
4. You cannot drain enough water out of the water heater to avoid freezing by simply opening the temperature/pressure release valve at the top of the water heater.
Here are the things that DO work
These are the steps I would recommend once you have made sure the fresh water tank and holding tanks are drained or nearly drained:
1. Drain the water heater by removing the drain plug. If using an air compressor, leave the drain open and blow the water lines out through the water heater drain.
2. Close the water heater bypass valves.
3. Now, if using RV antifreeze (clearly labeled for RV/marine use) use the pump in your RV and pump RV antifreeze through the system until, when opening each fixture one at a time, you have a solid pink flow. If using an air compressor, forget the RV antifreeze, but do the same thing with air pressure until no water comes out.
4. If you are using the RV pump and antifreeze, don’t forget the outside fixtures including shower and the city water inlet. If you simply push the center of the city water inlet in, it will release the back check valve and antifreeze will flow out. If using air pressure, make sure to run the pump dry.
5. Put the water heater drain plug back in the water heater and open the bypass valves. Pour a cup of antifreeze down each trap and you are done.
6. In the spring, flush the system until it is no longer pink.
If this sounds simple — it is!