For the lucky of us who are not concerned with using our RVs in below freezing temperatures, we do not have to worry about the dump valves on our tanks freezing in the winter. Unfortunately, the unlucky among us who live in their RVs year round or use their RVs and work in cold climes do.
Now there are a couple of ways to keep dump valves from freezing. One is to heat them with pads that have wires buried in them and are heated with electricity. Very few RVs used this method, although some manufacturers use pads to keep the tanks from freezing. I will note here parenthetically, however, that even RVs with special heated systems for their tanks and dump valves have a very difficult time when temperatures hover near 0 degree F.
Having noted the option which most manufacturers avoid due to cost and added complexity, let’s discuss what they do install to deal with the cold, remote dump valves. As the name implies remote dump valves are installed on the tank outlet above the sealed belly of the RV. In this manner, they are less subject to freezing, but a whole other type of problem is ushered in by using a cable to open and close the valve.
The most common problem cable operated valves have is the cable and valves are not installed according the manufacturer’s instructions and this problem is almost universal. Ideally the pull handle is installed in line with the action of the valve and and the cable is anchored at several points so it does not deflect when the valve is actuated.
In practice, however, cables are run in a variety of directions including S curves and are almost never (I have never seen a single one) anchored between the handle and the valve. Invariably as the valves are operated they gradually stiffen in action and increasing amounts of pressure are required to open and close the valve. Eventually the cable often pulls free of the valve body making operation impossible.
In another scenario, a bit of tissue may get into the valve so the valve will not close completely, never a good thing when the black tank continues to drip when the valve is closed. Now for the record, a service call to work on a system with a stuck dump valve and a full tank is almost universally avoided by technicians, as emptying a full tank by disconnecting a dump valve is less than pleasant.
To avoid this problem, RV owners who own RVs with remotely controlled dump valves should routinely use tissue dissolver in the black water tank and valve lubricant in all their dump tanks. The first product makes tissue less likely to hang up in the body of the dump valve when it is opened. Valve lubricant eases the action of the valve and makes pulling the cable out of the valve less likely.
Since there are times when even the best efforts of owners are thwarted, there is one other thing I recommend owners with remote valves carry with then and that is a 3″ twist-on dump valve. This redundant valve be placed between the dump hose connection and the dump hose, in the event of an emergency. With this valve in place, the entire dump system can be contained in the RV’s plumbing, until the defective parts can be replaced. Replacing remote dump valves on-site is a difficult process that should only be attempted in an emergency.
For those folks wondering if they have remotely controlled valves, they are most commonly found in mid-range and higher priced fifth wheels. For example, Cedar Creek fifth wheels have remote valves as do Big Horn fifth wheels. In the case of Big Horn, the dump tanks are stacked and onsite repair is all but impossible (in my opinion), so you have been forewarned. A $25.00 twist-on valve is a godsend if your dump system fails on the road, so pick one up and toss it in one of the storage bins, just in case!
Hope to see you one the road,
Steve (Mobility RV Service 423.341.8792)