Black Water Tank

[gridiron]

In a U-tube video that I saw one person suggested opening the black water tank to empty and then close the valve and turn on the wash jets and fill the tank to around 3/4s full and empty again. I tried that and it seemed that with my valve closed, that no water was going into my tank via the wash system (sprinklers). When I unhooked the hose, water came out of the hose attachment. Is this normal? Lazy Days in Florida told me to never flush the tank with the valve closed? What do you RV'ers suggest?

[subdoc4]

I was told the same as Lazy Days told you. Not sure why as it is vented?

[atom ant]

Gridiron,

How were you able to tell you were not getting water in the tank? I can't hear mine (or barely can), I just know its going in there because after a while when I open the drain valve it comes out.

The correct answer is you are not supposed to close the valve when using the wash. The risk is you walk away and forget it which floods the tank out your roof vent (assuming the stack would even hold a column of water) or anywhere else it's not tight like the vent gasket on top of the tank, toilet seal, etc. Worse case you actually damage the tank.



The real answer - most people do it anyway. I do. There is only one sprayer in there and I don't have confidence it does a great job by itself, so I close the valve and let it fill and run the risk that I won't overfill it.

[gridiron]

I just can't hear it, so maybe it is filling.....Does any water runout your hose attachment on the redwood when you take the hose off?

[gridiron]

by the way, I see where you have an onan LP....How do you like it? I am thinking about getting one, it is expensive..

[atom ant]

Originally Posted by gridiron

I just can't hear it, so maybe it is filling.....Does any water runout your hose attachment on the redwood when you take the hose off?

Yes, the water running out is normal (I always disconnect back at the source so I don't get wet ) The flush has an vacuum break type backflow pressure device that is mounted high in your RV. Under pressure, it closes to atmosphere and lets you flush your tank, but when you shut off the supply, the break opens to atmosphere and lets the downstream water run into the black tank and the upstream water to run back out the inlet by allowing air back into the line at the high point. This is a way to prevent cross contamination and stops siphoning (black water running back out the wash inlet until it gets down to the level of the spray head - yucko).



Our LP onan has been a great companion for us! It is a Marquis Gold and is now 10 years old and has been in 3 RVs. I just serviced it last week and everything looks like new - clean oil, etc. It should last us another decade or so

[gridiron]

Great news, thanks for all your help. Just got our Redwood 30 days ago and we are so excited about the whole thing. My wife and I just retired from teaching. 38 years each and now is time for some RVing.......
Thanks again

[atom ant]

Congratulations on that rig! I am certainly jealous of your adventure ahead!

[rcflame]

I have been putting water in the black tanks and flushing our campers for years. I drain the tank, shut the valve, let it fill to a point I know is safe, and open the valve again. Sometimes I do it a couple times if it still looks like bad stuff coming out the first time. The first time I do it on a camper, I shut the valve, have the wife watch the gauge, (sometimes have to shut the valve off to get a good reading if it is splashing on the sensors.) I will let it go just a short time after it hits the 2/3 mark and shut it off. I have been keeping track of the time as I'm doing this. Once I know how long it takes to get to that point, from than on when I dump I use that time to know I won't overfill the tank.

[Rick and Mindy]

Atom Ant has the right answer to why you should never close the valve when using your black tank rinse. I have a friend who has a rather expensive motorhome and closed his valve while using the black tank rinse and something came up so he walked away and forgot about it. His wife started screaming at him when she noticed wet toilet paper running down her windows on the outside of the coach. That is a true and very funny story but not to him. Anyway, I close mine all the time while I rinse and I do that several times when dumping the black water............just DON"T WALK AWAY!!!!!!!!!!!

[hoosierguy]

Originally Posted by Rick and Mindy

Atom Ant has the right answer to why you should never close the valve when using your black tank rinse. I have a friend who has a rather expensive motorhome and closed his valve while using the black tank rinse and something came up so he walked away and forgot about it. His wife started screaming at him when she noticed wet toilet paper running down her windows on the outside of the coach. That is a true and very funny story but not to him. Anyway, I close mine all the time while I rinse and I do that several times when dumping the black water............just DON"T WALK AWAY!!!!!!!!!!!

I do the same.........it is the only way to get the tank sensors to clear and show an empty tank. Generally takes 3 partial refills to get the tank water to clear. Then I dump the gray tanks.

[Blenhardt]

Originally Posted by hoosierguy

I do the same.........it is the only way to get the tank sensors to clear and show an empty tank. Generally takes 3 partial refills to get the tank water to clear. Then I dump the gray tanks.

I also do the same thing. Just make up your mind to not get distracted when doing this.

[mhs4771]

I'll add the extra step I do. After partly filling and dumping the tank approx 3 times, then with the valve open I go inside and fill the bowl to the top and flush approx 3 times. To move anything that might have piled up directly under where the pipe enters the tank.

[Dave&Ginny]

I was at one camping area where a guy thought the back tank flush was the city hook up.........big mistake. 30 minutes later and all hell broke loose.

[Adamsvr]

Depending on the water pressure at the RV park, I typically fill the black tank for 4 to 5 minutes with fresh water and then dump it. I do this 2 or 3 times. Just don't get distracted.

[almcc]

I'll make a comment about the black tank and flushing. We had problems with tank clogging on our 36RL, I thought that the problem was related to the fact that the sewer pipe from the toilet the tank doesn't go vertically into the tank, it's on about a 30 degree angle off the vertical. On a few occasions I had to reverse flush the black tank from the sewer connection and I had to completely fill the pipe below the toilet with water to clear the clogs.

A month or so ago the paddle fell off the Thetford toilet, I guess I could have gotten a replacement paddle under warranty (the trailer is less than one year old) but looking at the poor design and experiences of others I felt that a replacement paddle would only last for another year. I bit the bullet and replaced the Thetford with a Dometic, it was a "plug and play" install.

Since the replacement we've had no toilet clogs, I attribute the change to the fact that the Thetford paddle was not allowing sufficient water flow into the toilet and tank to provide enough dilution.

[atom ant]

Originally Posted by almcc

Since the replacement we've had no toilet clogs, I attribute the change to the fact that the Thetford paddle was not allowing sufficient water flow into the toilet and tank to provide enough dilution.

Since the flush on the Thetford is manual, and the operator controls the length of time and water quantity that goes with the flush, I don't think you can pin that one on Thetford. We have not had clogging issues.

[almcc]

Originally Posted by atom ant

Since the flush on the Thetford is manual, and the operator controls the length of time and water quantity that goes with the flush, I don't think you can pin that one on Thetford. We have not had clogging issues.

Actually, if you look at the paddle design (after it falls off!) if the paddle failed as ours did the flow of water was reduced progressively before the failure because the paddle didn't stroke the valve fully. I found this out as we had to manually turn the flush valve and water valve for a few days before I installed the Dometic (lots of water flow then!). Sort of the opposite problem that others are having with the Thetford (water not shutting completely off and causing flooding).

[travelin' texans]

After rinsing once or twice I will add about 2/3 of of a cap of el cheapo laundry detergent & rinse a couple more times, I do this about every second or third time I dump.

[RifRaff]

Book says tank valve has to be open.