Flushing Black Tank

[78Buco]

Just picked up a brand new Jayco the other day and the dealer was explaining something about the black tank that i have new ran across before. I have always in the past drained the black tank completely, closed the valve and filled the tan back up to roughly half and drained again, repeating this 3 times of so till tank was flowing clear.

Dealer told me this can't be done or the tank with explode from the pressure. Drain valve has to be open anytime the hose is flowing water to tank? Can anyone confirm this? For reference its a new jayco jay feather 30qb

[Robbbyr]

Originally Posted by 78Buco

Just picked up a brand new Jayco the other day and the dealer was explaining something about the black tank that i have new ran across before. I have always in the past drained the black tank completely, closed the valve and filled the tan back up to roughly half and drained again, repeating this 3 times of so till tank was flowing clear.

Dealer told me this can't be done or the tank with explode from the pressure. Drain valve has to be open anytime the hose is flowing water to tank? Can anyone confirm this? For reference its a new jayco jay feather 30qb

Dealers/manufacturers will specify that the black tank drain valve does need to be open whenever the flush is in use. It is a CYA statement. That is in case the operator becomes distracted and inadvertently leaves the flush going (with the drain shut) and floods the inside of their RV. It will not "explode" the tank. The tank has a vent pipe from the tank that goes up through the roof to allow odors to exit, AND to allow the tank to vent when it is draining. Without a vent it would be like a straw with your finger over the end, it won't empty. That vent will prevent overpressurization of the tank.

Having said that the tank won't "explode", it is a good practice to keep the drain open when the flush is going. Have I closed my drain while flushing to build up the water level and then opened the drain? You bet I have. But I am right there and do not do anything else when flushing like that.

Have I also heard of people leaving it run, or inadvertently hooked up to the flush connection thinking it was the regular fresh water inlet? Yes to that too. Water flowing off the top of the roof as well as flooding inside when it leaks thru the toilet. Big time cleanup.

[JimD]

After my initial drain of the black tank I will close the valve and use the built-in black tank sprayer. I allow it to fill for 2 minutes and then open the valve while leaving the sprayer going. After it drains I will repeat the process another 3 times. Water is running clear after 4 cycles.

I have the SeaLevel tank level monitor system with a display inside and outside in the wet bay. I watch the level as I am pumping in with the valve closed. It only gets up to about 25% when the 2 minutes are up and I am once again opening the valve.

[youracman]

^^^^^^^^^^ X2 ^^^^^^^^^

Just do it like you always have, Buco. It works.

With the external level sensors nowadays there really isn't much of a need to have a nice clean black tank at the end of the process, but IMHO, coiling up a nice clean "slinky" to put back in the MH bay is reason enuff to do the flush.

Still learning about my 31UL, but I don't believe that there is any "spray" to my rinse ........... or maybe my less-than-20-20 hearing isn't picking it up. Not that it matters cuz I just fill for several minutes and re-dump as described above. If the dump station is real busy, I only do it twice though.....to get outa the way.

Your experience is just one more instance where it seems to me that many an RV salesman has never even owned an RV......or taken a trip in one.

Good times and safe travels.

[jetlag]

After I drain mine I refill until the gauge says full. I am standing by the dump station with the phone and JayCommand APP. I will drain again and repeat for a second time, then close valve and add chemicals and around 10 gallons of water. I do this to both black tanks. my wife learned about the dreaded poop pyramid the hard way and do not care to repeat the experience. All of this via the two flush ports, and it hasn't exploded yet.
Once home, and we are lucky to have a small septic installed by the camper shed, I repeat the above but this time fill both tanks to the full mark with water and chemicals, and leave them that way until the next trip when I will drain and replace with 10 Gallons of water for the road.

[CAG]

Having said that the tank won't "explode", it is a good practice to keep the drain open when the flush is going.

True but I have read that a few unfortunate people have walked off while filling with the flush and the valve closed only to see sewage running out the vent and onto the roof, and down the side of the RV. The toilet valve usually keeps it all from flooding the inside of the RV before coming out the vent.

There is also the danger of over expanding the black tank and blowing the connections off. In either case an ugly scene. Don't walk away or become distracted while flushing, and just a note but I have found the back flush system at the dump valve to be more efficient than they installed flush systems.