Since the holding tank gauges that detect the levels in the various liquid tanks are so error-prone, what exactly is the gauge? What does it look like? How does it work? How is it replaced? Are there other systems being investigated/researched to make better gauges? Thanks. —James, 2020 Coleman 2515RL
The level gauge inside your rig shows the level in your black water, gray water, and fresh water tanks. The information is provided by a series of sensors in the holding tanks. Typically, there is a main 12-volt positive wire that runs to the 1/4 or 1/3 level on the tank, depending on how your gauge reads. A hole is drilled in the tank and the sensor is inserted and the screw tightened. This pulls or sandwiches a rubber gasket (similar to how a pop rivet works) and a rounded metal probe or sensor is inside the tank wall.
Then, another sensor is positioned about 6-8 inches directly across from the main power sensor and that is wired to the gauge inside. Another is slightly higher at the 1/2 or 2/3 level, and then 3/4 and full. When the fluid in the holding tank rises, it will provide continuity or allow the power to pass from the main power sensor to the lowest and up as it fills.
The challenge with this type of sensor is the material that can collect on the sidewall of the tank and still create continuity or false readings as the tank is drained. A good black water tank flush valve can help clean off this material, but it’s not always a perfect solution.
Stick-on monitoring system pretty foolproof
Several manufacturers of Class A units have gone to a stick-on monitoring system that uses a micro-electrical field rather than fluid creating continuity. They have been pretty foolproof. Winnebago calls its system TrueLevel and uses Mirus sensors. You can purchase this system from a Winnebago dealer but will probably need to swap out your monitor panel control board.
Another product is called the RecPro RV Water Tank Monitor System, which can be found on Amazon here.
The product comes with three sets of sensors, with three used on each tank. It also comes with a proprietary gauge and 15’ of wiring. It’s a very inexpensive option and looks to be easy to install. You just need to find a way to get the wiring up inside the rig to the location you want the gauge.
You might enjoy this from Dave
Ask Dave: Black water tank is clean but there are still smelly odors. Why?
After flushing the black water tank, there are still smelly odors like a sewage smell in the bathroom that seems to come from under the sink in the cabinet. I flush the waste tank until the water comes out clean and there is still a strong smell. Is there a one-way valve or something like that that may be stuck open? Thanks. —Luis, 2020 Winnebago Micro Minnie 1706FB
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
Read more from Dave here.