In 2006 and 2007, we had some horrendous odor problems with our Thetford Aqua Magic IV RV toilet. The toilet had water in it, which seals the tank quite effectively from the toilet - but the odor was still coming into our living quarters.
I cleaned the tank several times, and we tried several types of chemicals without any luck. It stank.
Thinking that the odor might be coming from where the toilet connects to the floor and tank, I replaced the closet flange seal - twice. This didn't help.
Then, thinking that just maybe the black water tank roof vent was clogged, I ran an old piece of hose down the vent pipe from the roof. Again, no help.
I checked the bathroom vent fan, and found that it WAS miswired, and blowing IN from the outside - from right near the vent stack. I fixed this by reversing the wires, but the odor remained.
I checked all the hoses for cracks, and tightened all of the hose clamp connectors at the tank and the toilet, although all seemed to be good and secure. No help.
I pulled the belly liner to inspect the tank and fittings directly, and found no evidence of leaks or odor.
Finally, in the summer of 2008, I solved the problem.
There is an overflow tube that extends from right near where flush water enters the top of the bowl directly to the black water tank. This is apparently intended to keep the toilet from overflowing if there is a small leak in the water valve.
The tube is curved, forming an "S" trap. If there is no water in the "S", there is a direct passage between the black water tank and the bathroom. Thus - BAD odors in your living quarters - regardless of what chemicals are in the tank.
To fill the "S" with water, simply fill the toilet to the brim. Let it stand for a couple of minutes to make sure the overflow trap is filled, and flush it down. Then, just use the toilet normally. It would probably be a good idea to repeat this a few times during the camping season, just in case the trapped water is sloshed out or evaporates.
At any rate, we have had NO ODORS SINCE WE STARTED DOING THIS!
For a diagram showing the overflow tube, see:
http://www.thetford.com/HOME/PARTS/Permane...18/Default.aspx
PALOD
I cleaned the tank several times, and we tried several types of chemicals without any luck. It stank.
Thinking that the odor might be coming from where the toilet connects to the floor and tank, I replaced the closet flange seal - twice. This didn't help.
Then, thinking that just maybe the black water tank roof vent was clogged, I ran an old piece of hose down the vent pipe from the roof. Again, no help.
I checked the bathroom vent fan, and found that it WAS miswired, and blowing IN from the outside - from right near the vent stack. I fixed this by reversing the wires, but the odor remained.
I checked all the hoses for cracks, and tightened all of the hose clamp connectors at the tank and the toilet, although all seemed to be good and secure. No help.
I pulled the belly liner to inspect the tank and fittings directly, and found no evidence of leaks or odor.
Finally, in the summer of 2008, I solved the problem.
There is an overflow tube that extends from right near where flush water enters the top of the bowl directly to the black water tank. This is apparently intended to keep the toilet from overflowing if there is a small leak in the water valve.
The tube is curved, forming an "S" trap. If there is no water in the "S", there is a direct passage between the black water tank and the bathroom. Thus - BAD odors in your living quarters - regardless of what chemicals are in the tank.
To fill the "S" with water, simply fill the toilet to the brim. Let it stand for a couple of minutes to make sure the overflow trap is filled, and flush it down. Then, just use the toilet normally. It would probably be a good idea to repeat this a few times during the camping season, just in case the trapped water is sloshed out or evaporates.
At any rate, we have had NO ODORS SINCE WE STARTED DOING THIS!
For a diagram showing the overflow tube, see:
http://www.thetford.com/HOME/PARTS/Permane...18/Default.aspx
PALOD