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Black Tank Flush Backflow Valve


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Black tank dumping/flushing has become a challenge lately.  Flow through the flush has slowed to a trickle.  I removed the valve next to the black tank and there is a rubber ring that was quite deformed and was half under and half over the valve.  I tried to reposition it then reinstalled it but there is no difference.  It’s an annoyance at a FHU site (30 minutes to get to 50%) but is unacceptable at a dump station.  I opened a trouble ticked with Oliver and it’s $58 for a new valve.  Seems high to me.  Does anyone know if this is something that can be purchased at a HD or Lowes or plumbing supply store?  I could fix it while on the road and not have to wait until we get home.  Here’s a picture of what I’m talking about.  It’s the gray part next to the tank.  Mike

 

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As far as I know, this is nothing more than a anti-siphon check valve.  If that is correct then virtually any check valve of that sort would work as long as the length and the fittings on the end are adaptable.

Of course another thing you can do would be to cobble a non-anti-siphon piece of pipe in there until you get home where you can search better for a "better" solution.  Certainly you will be very careful with any cobbled together solution and I'd guess that it would be technically illegal in many places.

Bill

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2023 Ford F150 Lariat 3.5EB FX4 Max Towing, Max Payload, 2016 Oliver Elite II - Hull #117 "Twist"

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Take it apart again, go to an Ace Hardware store and they should be able to match up the seal for a dollar or two at most. Buy a spare for your kit. Alternatively, if you are near a larger city, an RV parts supply store … If that doesn’t work, ask Oliver for the make and part number of the valve, you most likely can find it at an online vendor to at least see if their price is acceptable (it does seem very excessive unless it includes overnight shipping and hand delivery to your campsite 😬). I suspect it is a special RV part, most common types have female threads

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Take pics please. Good luck. What a sh**y project😬

John Davies

Spokane WA

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15 hours ago, Mike and Carol said:

Does anyone know if this is something that can be purchased at a HD or Lowes or plumbing supply store? 

It looks like an ordinary 1/2" MPT x 1/2" MPT check valve to me.  Pull the part and verify pipe diameter to be sure.  But, I'll bet the Pex pipe that connects to the valve is 1/2", so odds are high that the fitting is 1/2".

A brass version offered by Valterra (which would be an upgrade from the plastic one Oliver installed)  is available from Amazon for under $10:

https://www.amazon.com/Valterra-P23415LF-Lead-Free-Check-Valve/dp/B00HJ6P0Z8/ref=sr_1_5?gclid=CjwKCAjwwL6aBhBlEiwADycBICgly1OwtJDY5Q9FclIA3jCEEmcXbufHEPlR1A_rkK51r41DjwB-PRoCqMkQAvD_BwE&hvadid=616862894778&hvdev=c&hvlocphy=9029558&hvnetw=g&hvqmt=b&hvrand=2988426038172399198&hvtargid=kwd-315243267828&hydadcr=24633_13611805&keywords=1%2F2+inch+check+valves&qid=1666189161&qu=eyJxc2MiOiIyLjMwIiwicXNhIjoiMS44NSIsInFzcCI6IjEuNDYifQ%3D%3D&sr=8-5

Camping World sells the same fitting:

https://www.campingworld.com/12-brass-check-valve-x-mpt-95194.html

You may be able to find a Camping World, or even just an RV supply store, on your route that would have it in stock.

Good luck!

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Hull #1291

Central Idaho

2022 Elite II

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Some of those flushers come with a check valve built into the spray nozzle itself ,making an external one redundant. You should be able to see if yours does  by looking into the connection fitting. If it does, just take some needle nose pliers and break the guts out of that gray valve and use it as a straight nipple. 

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Thanks all.  We just arrived at our campground in Louisiana, far from any civilization and with barely a bar of cell coverage.  Tomorrow we’re in Waco for a couple of days and I will work on it then.  If I can’t find one there, I’ll order one of the top two in JD’s Amazon picture above.  Mike

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53 minutes ago, Mainiac said:

If, in the mean time, you want to flush the tank, you could just pour a bucket of fresh water down the toilet? Fix it at you leasure?

I’ll either do that or put a hose through the bath window.  I’ll probably fix it when we get home this weekend.

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Just to close this out….

 I ordered a replacement Thetford valve from Amazon, $8.  It’s one in the picture in John’s post above.  There are actually two valves, one inside the tank (white) which comes out when unscrewed and the gray one which is the one that went bad.  I put on new thread tape and reinstalled and we’re back in business.  The replacement is a little shorter than the original, but fit with no problem.  I’ve seen some pictures of what is in other trailers and they are not all the same.

 

Here’s the assembly and the new part.  The white part on the right is the second valve that screws into the tank.

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The new black valve replaced the old gray.

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Here it is back in place.

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Just wondering:  For those of us that have a isolation valve, why do we need a check valve?    

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17 hours ago, Mike and Carol said:

Just to close this out….

 I ordered a replacement Thetford valve from Amazon, $8.  It’s one in the picture in John’s post above.  There are actually two valves, one inside the tank (white) which comes out when unscrewed and the gray one which is the one that went bad.  I put on new thread tape and reinstalled and we’re back in business.  The replacement is a little shorter than the original, but fit with no problem.  I’ve seen some pictures of what is in other trailers and they are not all the same.

 

Here’s the assembly and the new part.  The white part on the right is the second valve that screws into the tank.

A834F376-7718-40E9-BCD5-617DEC267348.thumb.jpeg.e5e80ab670375778860522dc4716cb03.jpeg

 

The new black valve replaced the old gray.

64C89EC2-702B-4A86-9AE7-DD02DF2726AA.thumb.jpeg.6ed38c60163269086cd9c5f4b774b7e4.jpeg

 

Here it is back in place.

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Mike,

Nice job!

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8 hours ago, Geronimo John said:

Just wondering:  For those of us that have a isolation valve, why do we need a check valve?    

Good question.  Also, why do I have two check valves, one connected to the other?  I thought about just eliminating the bad one (gray in the picture) and just going straight to the one that screws into the tank (white one).

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The white one isn’t a check valve. It is a spray nozzle. The idea is to blast all around the walls of the tank, to get rid of the gunk that sticks there, not just fill it up.

Check valves provide one way flow protection. You do not want black water going back into the fresh water supply. That “normally” would never happen, but if something happened in the fresh supply system, it could possibly syphon  back and contaminate it. The RV codes require a functioning check valve here (complete separation of fresh and sewage systems). Just like residential code requires check valves when you connect up an irrigation system to city water.

The other check valves in the back of the trailer are installed to prevent your pressurized water from simply going the wrong way. It is all about traffic control, like one way streets. 

John Davies

Spokane WA

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16 hours ago, Mike and Carol said:

I’ve seen some pictures of what is in other trailers and they are not all the same.

Apparently Oliver has changed this arrangement up more than once.   My trailer does not  have any check valves on the black  tank, just a simple brass elbow, possibly connected to a spray nozzle.  Connected to it is a white pex line  that goes up under the sink in the head, attached to a brass vacuum break valve.  I think it also has a brass check valve.   Then it loops back down to the flush inlet on the side, also a simple brass elbow.   Since I have a Natures Head, this line is not used.   The heavy brass valves were  not secured, and rattled around under the sink.   I removed all of it and capped off the elbows, stored it away.  While I was under the sink, I easily removed the toilet water supply line and valve, also not used.   Now I do not have to winterize that  line.  I don’t have a pic of the vacuum breaker valve but I can get one if you are interested.    This vacuum break arrangement is not shown in the 2021 or 2022 Elite II owners manual plumbing diagram,  but it is shown in the Elite diagram.

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2 hours ago, Mike and Carol said:

Good question.  Also, why do I have two check valves, one connected to the other?  I thought about just eliminating the bad one (gray in the picture) and just going straight to the one that screws into the tank (white one).

Two check valves and initially a shutoff valve. Someone wanted to be absolutely sure? More likely just a case of not really understanding what was what. At least they eventually  eliminated the shutoff valve. The hookup kit for the No-Fuss flusher doesn't include much more than a garden hose inlet fitting and connection hose fittings. Valterra must figure the integrated check valve is enough to satisfy RVIA requirements.

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5 hours ago, John E Davies said:

The white one isn’t a check valve. It is a spray nozzle. The idea is to blast all around the walls of the tank, to get rid of the gunk that sticks there, not just fill it up.

When I looked at both valves when I disassembled them, they both looked very similar.  I assumed they were both check valves.  It makes sense that the one that screws into the tank is a spray.  Mike

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13 hours ago, bhncb said:

At least they eventually  eliminated the shutoff valve.

Personally, I prefer a valve I can close off vs. one or two check valves that can fail when they want to so as to cause the most adverse consequences.

But then I NEVER leave a pressure hose hooked up to our OE2 more than temporarily filling the fresh water tank, or flushing the black tank.  My rationale is that I have zero confidence that the pressure water system pressure for all the systems I load water from are at a level that will not damage my trailer.  With or without a pressure regulator.

Yes, that makes me run my fresh water pump a lot.  But when it fails, I for sure know where to look.    Just my two cents.

GJ

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  • 6 months later...

IMO, this post "sort of" fits the thread, and would fit others just as loosely, but we picked this one anyway because the posts were well thought-out and germane to what follows...

1. A few weeks ago, we ordered and received a "Flush-King" gate valve assembly to aid in determining the quality of the black water tank flushing operation.  There's other assemblies available that provide the same function, but this one seemed to better fit the OTT dump system.  Since our first stage dump hose stays permanently connect to the OTT dump exhaust flange, it's a simple procedure to place the Flush-King between the first and second stage hoses.

IMG_7410.thumb.jpeg.2e1f17f7364e2efce775ab9beaa36a3a.jpegIMG_7414.thumb.jpeg.2f2825f6718bdc24792de8f9fc53a146.jpeg

Final phase dump hoses connect to the downstream end of the FK and then over to our dump station.  The FK has a ball-valved garden hose attachment that is upstream from its gate valve (see above pic).  We didn't believe this attachment was necessary for Casablanca since the OTT has the "Waste Water Holding Tank" fill attachment discussed ad nausium in several threads.  The FK located close to the Ollie makes it convenient for us to observe the color of the waste because of the 30+ foot distance to our dump/septic connection - in other words, we no longer need to run back and forth from the dump connection to the trailer to control dump valves, water flow, tank fill progress, etc.

2. We attached a digital flow meter to the waste water holding tank fill inlet to monitor the amount of water flowing into the tank - also monitoring the See Level gauge for comparison, so as not to over fill the tank.  The See Level digital readout closely agreed with the digital flow meter as the tank was filled - this added a level confidence with the See Level system.  Upstream from the flow meter we attached a brass ball valve to control the fresh water flow from outside the RV and provide an additional safety check for potential interior check valve failure and subsequent back-flow of effluent into our fragile fresh water system.

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3. The waste water system took 3 flushes (54 gallons) to observe clear discharge at the FK assembly.  The discharge was clear and without debris when complete.  We filled the waste tank with 2 gallons of fresh water to keep from drying out until our next adventure.

Any thoughts of other steps that we're missing or have omitted?

Cheers - even though this is a "S**TY" job...

 

 

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Thanks for the details, Art! The flow meter is a clever idea.

I have an inexpensive macerator pump arriving today, so that I can more efficiently clean the system at home. I've wondered how many times the tank needed flushed to be reasonably clean. I'm getting a clear 45° connector, too, so now I'll be able to observe when it is clear.

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1 hour ago, MAX Burner said:

We attached a digital flow meter to the waste water holding tank fill inlet to monitor the amount of water flowing into the tank

O' ye of little faith! 😁

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2023 Ford F150 Lariat 3.5EB FX4 Max Towing, Max Payload, 2016 Oliver Elite II - Hull #117 "Twist"

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1 hour ago, Steve Morris said:

I have an inexpensive macerator pump arriving today

@Steve Morris please share details of the macerator pump you are getting. I am looking at one too for a possible permanent mount in my bumper.

Look forward to what you learn.

Brian

 

 

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On 10/19/2022 at 12:51 PM, Mike and Carol said:

I’ll either do that or put a hose through the bath window.

 

On 5/30/2023 at 5:21 AM, Steve Morris said:

I'm getting a clear 45° connector,

Max:  Nice set-up for using being able to super clean your black tank at home station.  hanks for providing the amount of water necessary to get to the clear flow condition.  It will cut down on the number of trips out to the clear sewer hose fitting.

My very first purchase after picking up Ollie was a 45 degree clear fitting.  They had them at the Hohenwald Walmart.  

In our case I need to do the full end of season black tank flush at a dump station or at an RV park with hookups.  As Mike & Carrol and Steve; I use a clear fitting and a gray hose to the black tank flush valve and my white hose with a ball valve on the end through the bathroom window.  I can control the inflow to the black tank from inside Ollie via the OTT OEM shut off valve and the ball valve on my white hose feeding water through the toilet flush valve that I have opened and held down by my military canvas tool bag.  

What has amazed me is that the process has never  not yet created a spray out the toilet from the tank flush system when I have the toilet flush valve held open.  (Hint:  As there may be differences in your tank and its flush nozzle, recommend careful execution the first time.  (Think images of a National Lampoon's Griswold Camping Toilet Repair effort) 

PS:  My white hose never comes into contact with the toilet.  

GJ

 

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1 hour ago, Geronimo John said:

I use a clear fitting and a gray hose to the black tank flush valve and my white hose with a ball valve on the end through the bathroom window.  I

Please forgive my ignorance, but why the white hose through the bathroom window and into the toilet?  Is the Oliver-installed flush valve below the window not good enough?

 

Hull #1291

Central Idaho

2022 Elite II

Tow Vehicle:  2019 Tundra Double Cab 4x4, 5.7L with tow package

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3 hours ago, Geronimo John said:

What has amazed me is that the process has never created a spray out the toilet from the tank flush system when I have the toilet flush valve held open. 

OK, guys - FULL DISCLOSURE:  When rigging this flush system yesterday, we were discussing where the displaced air from the waste tank is venting...  So about 8 or 9 gallons into the first "flush", I have the brilliant idea to inspect the commode ball valve.  After a "mini-Old Faithful" shooting up a foot from the ball valve, I realized it was NOT a brilliant idea.  All good in the "end" - so to speak... Whew!

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