BAC Forum
General Boards => Technical Support => Topic started by: Roy Lewis on February 20, 2018, 07:37:45 PM
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When filling the freshwater tank on tank fill mode" monitor panel the readings are incorrect ( tank is filling on gauge much faster than what it actually is. I believe I have an air bubble in the tank is this correct assumption and if so how do I rectify it? Thank you in advance for any answers.
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Roy,
I believe your tank level sensors rely on water in the tank to conduct a signal that indicates the level. If so, an air bubble wouldn't cause an erroneous reading, but water on a sensor before the actual level reached it could cause the symptom you describe. Possible causes could be splashing in the tank during fill or a piece of debris at the tank inlet causing some of the input flow to be diverted to the side of tank containing the sensors. If the tank level reads accurately once the tank is filled and as it empties, this may be what is occurring.
Steve
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Our black tank has a similar issue, but our grey and fresh water tanks read correctly. Some tank fill level sensors are weight sensitive and placed on the tank bottom, while some are continuity sensitive and placed vertically on the side wall. I think we have the weight sensitive type. I am not really sure which type our coach has, nor yours.
Note: If black tank solids stick/sit on the tank bottom on the weight sensitive pad, then their weight causes a false reading. Thus, we try to flush TSP down the toilet intermittently to keep the solids from sticking. Regular TSP treatments and black tank flushing seem to correct the issue.
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David and Roy,
I think that both of your coaches use a pressure sensor in the side or end of your tank, near the bottom. As the level in your tank increases, the weight of the liquid in the tank adds pressure to the sensor and the electronics in the sensor system read the increased pressure as an increase in level. I think that the 2000 was the last Marquis that used the proximity sensors that Steve was describing.
Roy,
Your erratic readings are not caused by an air bubble, but it is either a restricted tank vent that is causing excess pressure in the tank as it fills, or a defective sensor.
David,
You can correct some of your sensor problems by removing the sensor, and installing a street elbow where the sensor screws into the tank with the open end facing up and screw the sensor into it facing down. This leaves a very small air pocket at the sensor diaphragm so that solids will not cake up on it. I would also install a new sensor while I was working on it. Your black tank sensor is in the end of your tank, just behind the stainless steel panel in your sewer bay.
Gerald
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Thank you so much. Gerald!