How I Winterized my SMB Sprinter

How I Winterized my SMB Sprinter
Wow, this fall was great. The warmer-than-usual temperatures were perfect for road bicycling and camping in our new SMB Sprinter.
Finally, in early December, the bill came due and temperatures began to get below freezing at night.
We like to take the Sprinter out at random intervals, one to two weeks apart. Camping in cold temperatures at night was possible and by then we had experienced temperatures in the low 20 F range with no problem. Bringing the van home after one such trip lead to the question of winterizing. Since I wanted to be able to just get in and go we first tried a 120 volt heater left on inside. We found that while this worked well enough, the economy of keeping the van heated to 50 F was not appealing.
So, next I tried draining all of the water out by gravity. First I removed the water heater anode and opened the "low point drain". I also removed my water filters and blew the city inlet out with 40 psi air. This worked fairly well except for a low spot that had been built in to the plumbing.

This picture was taken during the fabrication of the SMB Sprinter. I found that both the hot and cold water lines running from the water heater to the galley on the opposite side of the van were required to pass by the shower. This necessitated that they be routed at floor level (also a concern due to insulation) in order to get by the shower. Since the taps on the water heater are elevated, this resulted in a low spot that just would not drain out by gravity.



This would have been a good spot to build in a low point drain, but it had not been done. So, for the next few weeks I installed a 100 watt light bulb in the area of the low spot and all was well.
Now it was mid-December and really getting cold at night. We were anticipating not using the van for time periods of up to three weeks. I had always told my RV customers that the only way to fully insure that their RV would be protected from freezing would be to pump in RV antifreeze. This method displaces all water that remains in the system after draining and insures that the delicate water pump is fully protected. So I acted on my own advice and proceeded to winterize with antifreeze.
RV antifreeze is non-toxic, protects down to -50 F, and dyed pink so that you can see it in action. There has been some discussion on the SMB forum that the antifreeze leaves a taste and many prefer to use cheap vodka instead!
I decided to use the antifreeze by sucking it into the system at the pump, thus allowing me to remove and bypass the city water filter using air pressure to evacuate to the fresh water tank so that no antifreeze would be introduced there.


So looking at the way the pump was installed I saw that I had a problem.
The pump had been installed up under the galley sink on the right hand side. Not a bad location and much easier to get to than some that I have seen. Yet it had been installed with the inlet side toward the back of the cabinet with the filter bowl up. I had discovered during my attempt at draining for winterization that an air bubble would get trapped in the bowl causing the pump to starve.
.

Pump Installation from the side
It was difficult to reach around to the inlet side of the pump in order to install a suction tube, but not impossible. I was able to winterize the van once this way but knew that something better could be done.

Pump installation from the front.
My solution to this problem was to turn the pump upside down. I was able to use the same mounting holes and it also resulted in the inlet filter bowl being correctly oriented.
I will admit that the plumbing is a little "awkward" but the result is effective. I can now easily remove the inlet hose and connect a suction tube for the antifreeze.


It takes less than 30 seconds to pump antifreeze into the system and uses less than a half-gallon, including a cup in each trap. De-winterizing should be simple with a city water hook-up and I may be able to re-use the antifreeze.

Now I can sleep without worry when the nighttime temperatures dip into the low teens.
Ready for the next outing...
JIM