Blackwater sensor problems

[dflickinger]

Here is my strange tale.

After dumping my blackwater tank, I started to fill the tank with water through the supply connection (with the blackwater tank valve closed).
I forgot (that day), that I was filling the tank and suddenly my wife and I heard and felt a "Thunk" sound. I ran to the tank and cut off the water then went to the toilet and found it half full of sewage. I checked everything and all seemed well, no leaks and everything working (and is still working), as it should, (lucky I guess).

Then someting strange started happening....I noticed that when I emptied the BT (blackwater tank) and then flushed the tank, the sensor lights would go down to empty as expected, BUT.... within 24 hours the sensors would read FULL again. I would go out and open the BT valve but I am sure that I would not get a full tanks worth of fluid from the tank. Everytime I empty the tank and flushed, the sensors react as they should (red to yellow to green to green) but again, within 24 hours it would be green to green to yellow to red.

Has anybody ever heard of this! Could something be filling the BT tank with water? Can the sensors really respond like this. The Sensors are reading correctly on the way down, just not (I hope), on the way up.

Let me know if anyone has ever had this problem

Thanks

[DAN L]

Originally Posted by dflickinger

Here is my strange tale.

After dumping my blackwater tank, I started to fill the tank with water through the supply connection (with the blackwater tank valve closed).
I forgot (that day), that I was filling the tank and suddenly my wife and I heard and felt a "Thunk" sound. I ran to the tank and cut off the water then went to the toilet and found it half full of sewage. I checked everything and all seemed well, no leaks and everything working (and is still working), as it should, (lucky I guess).

Then someting strange started happening....I noticed that when I emptied the BT (blackwater tank) and then flushed the tank, the sensor lights would go down to empty as expected, BUT.... within 24 hours the sensors would read FULL again. I would go out and open the BT valve but I am sure that I would not get a full tanks worth of fluid from the tank. Everytime I empty the tank and flushed, the sensors react as they should (red to yellow to green to green) but again, within 24 hours it would be green to green to yellow to red.

Has anybody ever heard of this! Could something be filling the BT tank with water? Can the sensors really respond like this. The Sensors are reading correctly on the way down, just not (I hope), on the way up.

Let me know if anyone has ever had this problem

Thanks

it would help if you would update your signature info with data about your rv. it would be nice to know what company manufactured your toilet too.

[cardiffman]

There is only two ways of filling the black tank: Through the top, the toilet, and with the flush hose. I'm assuming that Winnie installs an anti-siphon valve in their flush line as required by code. It's a little in-line water valve that only allows water to flow toward the tank and not back into the water system.

I find that sensors in almost every motor home I have owned (several) are less than accurate. I use them as a guide, not like gas gauges. My Adventurer has a wonderful and totally accurate fresh water gauge: You open the baggage door and look at the level! Alas, the black/grey tanks are not as clear, but cleaning with recommended gauge cleaners on a regular basis helps. Also, the irregular usage that most RV's get tend to add to the problem rather than help.

[bachler]

On most of the Motorhomes we have owned there has been a cross fill. Meaning Eather the Main sink or bath sink or the shower or the washer. One is allways plumbed in the the Black water tank. It is done to have enough liquid in the tank to drain it;;. on several of the coaches we have taped the toilet lid shout; Yet the black water tank would fill.. Life is good; sometimes Troubling;

[motohomer]

If you still have the same rig, there is nothing but the toilet, flush line, and stack connected to your black tank.
http://www.winnebagoind.com/diagram/...40fd_plumb.pdf

Perhaps you are just reading condensation on the sensors - common in the morning.