Black tank flush vacuum breaker

[asherwin]

I have gone through three of these in the last six months. Each failure has resulted in wet carpet in the basement. I would prefer not to go through this again. Is it ok to replace the vacuum breaker with a normal check valve? If not, why not?

 

[rxbristol]

You'll get replies where individuals have permanently removed the vacuum break, I personally don't believe that should be done due to the probability of sewer being drawn back into the freshwater system--which means your fresh water lines and hoses and the campground's system. Install an upgraded version such as the Watts LF228A. I've had mine for years with trouble-free service. You'll need some extra fittings to install it. Here's a link where you can buy it:

https://www.supplyhouse.com/Watts-0...UMK4aW7E4bB02E0uIJ6QMfGHHwSCbjU8aArx1EALw_wcB

 

[LBR]

I have gone through three of these in the last six months. Each failure has resulted in wet carpet in the basement. I would prefer not to go through this again. Is it ok to replace the vacuum breaker with a normal check valve? If not, why not?

The factory has to install an approved device or assembly for any high hazard connection.....this case is were a potable water supply is hooked to piping that can have contact with sewage. If a backflow situation were to happen, that black tank sewage can contaminate drinking water. A single check valve is not an approved device, so a vacumn breaker was used.

Since you now own the trailer, you can do whatever you see fit with the black tank flush system. Many here do install a single check and call the project done.

 

[SNOKING]

What I did was install a inline manual valve at the wash input fitting.

https://www.amazon.com/Orbit-58086N...19&sr=8-4&keywords=garden+hose+shut-off+valve

Then with a 90 degree quick disconnect adapter for the hose.

When you leave the flush hose connected to the trailer all winter and/or all summer, it is best to turn off on both ends.

Guy behind me last winter had the park replace his faucet and they turned both the city water and wash hoses back on and walked away. Cost the park a lot to refurb their trailer. They now will not turn water on, you have to do it your self.

BTW our VB is MIA. On our previous trailer the VB failed the first time I used the tank wash and the VB went MIA on that trailer also.

Chris

 

[wdk450]

If you go to an RV or trailer supply parts store you will find add-on black tank sprayer systems for sale like this: https://www.amazon.com/Camco-40126-Tornado-Rotary-Rinser/dp/B000BUU5TU . As you can see by the illustration this add-on black tank sprayer kit DOES NOT include an atmospheric vacuum check breaker like in the B&B Molders brand unit installed in Heartlands. The Camco add-on unit does have a check valve built into the connections.

You can draw your own conclusions on whether the atmospheric vacuum check valve that blows out under high water pressures is really needed.

You can get a Sharkbite brand 1/2 inch PEX check valve at any Home depot or Lowes store. The Sharkbite brand fittings simply slip on to cutoff PEX tubing ends.

BTW, after the first occurance, I would have added a water pressure regulator to my freshwater hose.

 

[avvidclif]

I have a dedicated tank flush hose which has a cheap pressure regulator on it. Helps to prevent blowouts at the high pressure parks. Never had a problem with a vacuum breaker, knock on wood.

 

[Gary521]

These vacuum valves seem to be a continual problem. Mine has never worked. Yes, I replaced it with a check valve and bypassed the vacuum thing. Using a separate hose for flushing and keeping the tank valve open will minimize any chances of water backup and cross contamination.

 

[asherwin]

Thank you for your valued responses. For those suggesting I need a pressure regulator, I have had one on the flush inlet from day 1.

Cheers

 

[Bogie]

Thank you for your valued responses. For those suggesting I need a pressure regulator, I have had one on the flush inlet from day 1.

Cheers

Could your pressure regulator possibly be faulty? Might be worth a look see since you have had multiple failures.


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[JohnDar]

Several years ago, the plastic inlet for my tank flush broke, so I replaced it with a brass city water inlet with a check valve. More recently, the plastic ASV broke in the wall cavity and flooded the area by the entry door. So, I ripped the plumbing down and installed a Sharkbite check valve in it and attached the line to the floor under the toilet. The water pressure has never been above 45 psi, so it’s not the cause. If you actually look at those B&B parts, they’re junk.


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[dykesj11]

I'm thinking my situation is similar to what you had. My black tank flush line comes in through plastic hose connector in UDC, connects directly to PEX run going up behind the shower to what I assume is anti-siphon valve, then back down to the tank. Whenever I used it, I would have some small amount of water run back down the outside pex line toward the UDC. I think what you described is what I've been pondering - replace the plastic hose connector with a brass backflow preventer, run the PEX directly across under the floor to the tank. I thought I might even add a Sharkbite inline check valve on that end. Do I have the correct understanding of your modification?

I can't help but wonder why the factory would use 12-15 ft with an ASV versus an 8 ft run with real backflow protection. Any thoughts? Until I found your post, it's what has kept me from just doing this mod. Thank you for posting. (I love this forum.)

 

[danemayer]

RVIA says:

When installing listed permanent in-tank sprayingdevices, be sure to use the provided vacuum breaker on the supply line to prevent cross
connections between the fresh and waste water systems. With the potable water and waste
water being in direct contact, if a change of potable water pressure occurred in the system,
without a vacuum breaker, waste water could be drawn into the potable water system, creating
an eminent safety hazard.

Presumably they know about check valves but call for a vacuum breaker.

 

[JohnDar]

I'm thinking my situation is similar to what you had. My black tank flush line comes in through plastic hose connector in UDC, connects directly to PEX run going up behind the shower to what I assume is anti-siphon valve, then back down to the tank. Whenever I used it, I would have some small amount of water run back down the outside pex line toward the UDC. I think what you described is what I've been pondering - replace the plastic hose connector with a brass backflow preventer, run the PEX directly across under the floor to the tank. I thought I might even add a Sharkbite inline check valve on that end. Do I have the correct understanding of your modification?

I can't help but wonder why the factory would use 12-15 ft with an ASV versus an 8 ft run with real backflow protection. Any thoughts? Until I found your post, it's what has kept me from just doing this mod. Thank you for posting. (I love this forum.)

Sounds like you understand what I did. If your line runs behind the shower, you may be able to access the ASV through the port under the shower controls (assuming there is one). If so, they do make real ones made of brass that you could replace it with. With mine, I would have had to rip a hole in the wall.

I used the Sharkbite check valve to join the lines after cutting the broken plastic ASV off.

If RVIA really gave a crap, they’d specify a brass ASV instead of some poorly molded plastic PoS and insist it be installed so it’s accessible by the consumer.

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[dykesj11]

Sounds like you understand what I did. If your line runs behind the shower, you may be able to access the ASV through the port under the shower controls (assuming there is one). If so, they do make real ones made of brass that you could replace it with. With mine, I would have had to rip a hole in the wall.

I used the Sharkbite check valve to join the lines after cutting the broken plastic ASV off.

If RVIA really gave a crap, they’d specify a brass ASV instead of some poorly molded plastic PoS and insist it be installed so it’s accessible by the consumer.

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Out of curiosity, while brass would for sure be better than the plastic PoS, why would the ASV be preferable to just running a line across with the check valves? I guess check valves can fail but so can ASVs, right?
Thanks John

 

[JohnDar]

The idea behind an ASV (or vacuum breaker) is to have an air gap so water and cooties can’t pole vault back to the potable water source. Personally, I believe a check valve will serve the same purpose, i.e., prevent backflow into the potable system. Especially with two check valves.

I feel RVIA is a bit like NFPA. Standards written by those that sell the products, not the people that have to actually deal with the products.


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[porthole]

Years ago when I first read about the cheesy valve breaking and flooding someones RV I changed mine.


I cut the lines in the basement where they go up and back down the walls.

Connected the lines eliminating about 12 feet of PEX

I installed a one way check valve at the water docking station inlet. I have two 1/4 turn valves that have to be opened to push water through that line.

Closing the valve right in front of the check valve then the primary valve means I always have pressurized fresh water in the line.

Or you could replace the plastic valve with a bronze version like this, but don't go through the trouble to add a bronze valve and then top it off with plastic connectors.

 

[LBR]

Out of curiosity, while brass would for sure be better than the plastic PoS, why would the ASV be preferable to just running a line across with the check valves? I guess check valves can fail but so can ASVs, right?
Thanks John

As I had mentioned in post #3, the factory has to install an approved assembly or device when sewage and potable water is able to be cross connected. A one way valve is not such a unit by code.

This is a High Hazard cross-connection and the only other assembly factory could have used is an RPZ..and trust me, you should be very happy you don't have one of them onboard!!

The ultimate option for factory is to not install a black tank flush.