Black Tanks Won’t Flush

[ENG2242]

I have two black tanks that discharge out one outlet. I have two unmarked black tank connections in the water compartment. Connecting to one, no water flows, when connected to the other, water discharges out the other. I tried a Y connection with no luck. I checked the only one way valve in the shower and it appears to be plumbed correctly. I cannot find another. Any suggestions?? Thanks David

[frankwp]

I have no idea if this will help because the OP hasn't provided any clarification. The black tank flush in my fifth wheel quit working, as in water would not flow. I unscrewed the nozzle from the tank to inspect it. It has a screen on the end & it was completely clogged with fibrous material. I cut the screen off & soldered on a short length of copper tubing with the end pinched a bit & reinstalled it.

The flush nozzle now has its discharge aimed in such a fashion that it causes a circular flow in the tank. It really flows a lot of water now.

[schlep1967]

I'll take my stab at this.
Following the title you are trying to rinse out your black tank(s).
Your post says you have two unmarked connections. I'm guessing for water hose hook-up to rinse the tank(s).
This is the hard part because every brand, model, year of trailer can be different. In my wet bay there are 3 places to hook up a water hose. A city water connection that goes straight into the water lines. An onboard water tank hook-up that fills my onboard fresh water tank. And a black tank flush hook-up.
My guess is that the one you are hooking up to that is not then running out of your black tank is filling your onboard fresh water tank.

[down_home]

Do you flush your tanks or just rain them?
If you just drain them there is the cause of the problem...unless the valves are bad. They don't cost much and are easily changed but not a job i want with tanks backed up. If you determine the valves work and you have some capacity left in the black tank, pour a bottle of water softener in and good amount of detergent then ice, at least 20 lbs, if you can. Have it already hoked up and drive it on the roughest rad you can find for a couple hours. See if that helps. If not, perhaps, since I haven't tried it a snake up the outlet with the valves open of course..with a painters suit on or some such but don't be too aggressive you don't want to damage the valve seals or valve,I don't like this idea a lot, for obvious reasons but....

[bucky]

Google isn't always correct due to the info it receives. Our FR 5er lists one grey at 60 gallons. It really is 2 30 gallon tanks with one pull handle behind a round cosmetic port 4 feet from the wet bay and the other in the wet bay beside the black tank pull.
One grey is bath, the other is kitchen.
Looking at the 5er specs you might want to find a scale so that you know what you are dealing with truck spec wise.

[MrWizard]

I think he is saying he has 2 black tanks and only one will rinse from the installed sprayer

I think there is confusion , I think he has the , 1 grey. 1 black, grey water tanks don't normally get a rinse sprayer installed in a grey tank

[frankwp]

Perhaps the OP could better explain the problem, because it's about as clear as black water 🙂 I can't tell if its the drain connections or sani-flush or what.

[MrWizard]

Gray tank and black dump to the same outlet
Drain down the one hose,
One 3inch pipe and valve for the black tank,
And a smaller valve and pipe for the grey tank 1&3/4 inch pipe I think !
Personally my RVs have never had a grey tank rinse, I have only had black tank sprayer rinse,
And this RV does not have any at all, I end up flushing lots of clean water down the toilet to rinse the black tank, does not clean the tank sensors, No bathroom window and I don't like dragging a water hose thru the RV to use a spray wand down the toilet,

Two black tanks will have two 3 inch slide gate valves on 3 inch pipes,
Look at the valves , handles, and pipes
One large and one smaller is normal

[kellem]

I'm betting you have a grey and black discharging together.

Have you properly identified all available connections such as fresh water fill, city hookup and black tank flush ?

Sorry for sounding elementary but not quite wrapping my head around this scenario your experiencing.

[jwoods61us]

According to the Google you only have one black and one gray tank.

Specs for 2018 Heartland - Bighorn
Floorplan: BH 3870 FB
(Fifth Wheel)

Holding Tanks

Number Of Fresh Water Holding Tanks1
Total Fresh Water Tank Capacity 65.0 gal.
Number Of Gray Water Holding Tanks1
Total Gray Water Tank Capacity 90.0 gal.
Number Of Black Water Holding Tanks1
Total Black Water Tank Capacity 45.0 gal.

[way2roll]

Trying to understand your issue. Is it that you have 2 black tanks and one drains while the other doesn't? What's a "one way shower valve"? How long have you had this Rv and did it work before? If the 2 connections in the wet bay are unmarked, how do you know they are for the black tanks? And if you have 2 blacks into one outlet, then how do you have 2 black tank outlets in the wet bay? Sorry for all the questions but I am really confused about the issue you are having.

[ppine]

Add two bags of ice. Drive for awhile, then empty your tanks.

[LadyRVer]

Could there be another slide valve located somewhere underneath? I had motorhome which had shut-off slide valve which had to be opened before it would come out the
normal outlet... sort of a safety situation. Just a thought.

[alisonsawyer]

Using a pressure washer or power washer.***Link Removed***