black tank flush

[youroo]

Originally Posted by Sherol

The last time we ran it it flooded the bedroom floor and filled two storage compartments with water. So I am thinking it may be under the bed. Will pull the slide out and lift the bed and see. Since we are in storage and have no water available, it would be difficult to run water to find it.

For those of you trying to locate "Water Leaks" use "AIR" low pressure air makes Noise and you can let it run without Water Flooding your unit! Most Water leaks make "NO Noise"! Youroo!!

[jd-ford-hd]

Originally Posted by IDguy

The good news is that you don’t ever need to use the black tank flush. Nearly all my RVs over the last 50 years didn’t have one.

Thank you.! I always cringe when watching people pull in to their spot, level up, hook power, hook fresh H2O, hook sewer line and then promptly pull the black tank valve open which remains open for their entire stay.!! My sewer hose gets used on the third day to dump some "gray" only. My wife and I will not fill our "black" tank in 5/6 days. The black stays in the tank for the ride home/next RV park sloshing around and dissolving solids. Then dump the "black" first, followed by the intentionally saved "gray" which rinses out the the hose with our soapy shower water.! I know everyone may not have a place to dump at their home but with planning, could find a dump station nearby.

[bubbles]

Originally Posted by jd-ford-hd

Thank you.! I always cringe when watching people pull in to their spot, level up, hook power, hook fresh H2O, hook sewer line and then promptly pull the black tank valve open which remains open for their entire stay.!! My sewer hose gets used on the third day to dump some "gray" only. My wife and I will not fill our "black" tank in 5/6 days. The black stays in the tank for the ride home/next RV park sloshing around and dissolving solids. Then dump the "black" first, followed by the intentionally saved "gray" which rinses out the the hose with our soapy shower water.! I know everyone may not have a place to dump at their home but with planning, could find a dump station nearby.

You say black tank valve but could it not be gray tank valve instead? I typically leave my gray tank valve open during my entire stay.

[nomad297]

Originally Posted by checkmate

Master Plumber. Done.

Stick around. You will find that most people who own RVs are Master Plumbers, just like you and I.

Bruce

[vestup]

Originally Posted by Sherol

We were winterizing our 2018 3011 DSF. When we attached a hose to the black tank flush, no water came out after a minute or so. We have flushed many times before and knew something wasn't right. We shut the water off to the hose and I could see water running onto the ground on the opposite side of the motor home. I went in to find the bedroom and shower area flooded with water. We cleaned up and then found that the storage compartment with the water pump was also flooded. We tried looking under the motor home but it seems everything is sealed. We are also in our upper 70's and crawling around under a motor home is not easy for us. We will need to hire someone to repair this and was wondering if there is any type of diagram for the plumbing system that might help them.

So sorry for this incident, I went and found mine for a 2020 2506s in case anyone needs to know on this model. Good luck with your repair.

[Mr. Dan]

Originally Posted by nomad297

Stick around. You will find that most people who own RVs are Master Plumbers, just like you and I.

Bruce

Good point!
............ and some of the worst/most dangerous electrical advice on this site has been given by some who claim to be 40+ years certified master electricians - yet have never been around RV electrical systems.

[bubbles]

Originally Posted by checkmate

Actually the 6” air gap is a requirement that is part of the national plumbing code. It is accepted plumbing practice, even in a recreational vehicle. That is why every RV with a black tank flush system has one.
Retired Master Plumber. Done.

Didn't say it wasn't applicable to an RV. What I said was because the black tank flush is a closed system unto itself there is no 6" air gap (open orifices for pressure and drains) applicability. The water outlet for the black tank flush system is in the black tank. I think this is correct:

An air gap, as it relates to the plumbing trade, is the unobstructed vertical space between the water outlet and the flood level of a fixture. Air gaps of appropriate design are required for water safety by legislation in many countries.

That's my story and I'm sticking to it.

[boatwhyteh2o]

My understanding is since the flush is a closed system the vacuum breaker is there to protect the rv park water system from back siphoning in case of a loss of rv park water pressure while your flush hose is connected to the trailer and RV park water system. After multiple failures, for better or worse I bypassed mine. I never leave the hose connected to the flush connection and the hose I use has an anti back flow fitting on the RV park end. No more floods. I’m not recommending removal of the valve but it was the only way I could solve the problem.

[Duckogram]

OMG First post since 2011. That is clearly a record setting event. Welcome to the FRF. What model Forester/Sunseeker do you have?

There are better valves available these days if you are interested.

[boatwhyteh2o]

Thanks for noticing Duck, I get the “digest” every week or so, but obviously don’t comment. I currently have a 2016 Heartland Bighorn 5th wheel. I just went through this vacuum breaker leak this summer on my new to me fiver. I tried a high quality device and it also leaked. I think it may be due to low water pressure. There needs to be enough pressure to seal the valve, but i don’t know for sure.
We travel from Phoenix area to NE Washington state where we stay for four to five months in the trailer, then back to our home in AZ for the winter.
I’m surprised my password still worked.

[vestup]

Originally Posted by Sherol

We were winterizing our 2018 3011 DSF. When we attached a hose to the black tank flush, no water came out after a minute or so. We have flushed many times before and knew something wasn't right. We shut the water off to the hose and I could see water running onto the ground on the opposite side of the motor home. I went in to find the bedroom and shower area flooded with water. We cleaned up and then found that the storage compartment with the water pump was also flooded. We tried looking under the motor home but it seems everything is sealed. We are also in our upper 70's and crawling around under a motor home is not easy for us. We will need to hire someone to repair this and was wondering if there is any type of diagram for the plumbing system that might help them.

Hopefully I won't get in trouble with the rv police, but I can't have a potential flood hanging over my head. I changed out the vacuum break and added an external one. I will leave this external break permanently attached to protect the park water. I kept the old one for an easy swap back if this is an egregious error in judgement or warranty issue.

[bubbles]

You have now overkilled the overkill.

[vestup]

I can neither confirm nor deny that statement :-)

[nomad297]

Originally Posted by vestup

Hopefully I won't get in trouble with the rv police, but I can't have a potential flood hanging over my head. I changed out the vacuum break and added an external one. I will leave this external break permanently attached to protect the park water. I kept the old one for an easy swap back if this is an egregious error in judgement or warranty issue.

This (and any other hose thread backflow device) is not suitable for any health hazard cross connection. It is a single, spring-loaded diaphragm check valve with a manually-operated vacuum breaker that is designed to break the vacuum in the hose only, and it is removable. The vacuum breaker on this device will be of no benefit for the purposes of a vacuum breaker in a black tank flush system. It certainly isn’t overkill, but I guess it is better than nothing...for now. The thing is, you have changed the designed system, and one day, somebody other than you is going to own that RV and they probably won’t know about the dangerous health hazard modification made to the flush system.

Something to think about.

Bruce

[vestup]

Originally Posted by nomad297

This (and any other hose thread backflow device) is not suitable for any health hazard cross connection. It is a single, spring-loaded diaphragm check valve with a manually-operated vacuum breaker that is designed to break the vacuum in the hose only, and it is removable. The vacuum breaker on this device will be of no benefit for the purposes of a vacuum breaker in a black tank flush system. It certainly isn’t overkill, but I guess it is better than nothing...for now. The thing is, you have changed the designed system, and one day, somebody other than you is going to own that RV and they probably won’t know about the dangerous health hazard modification made to the flush system.

Something to think about.

Bruce

Excellent comment, it’s an easy two minutes restoration, I think I’ll put it back and just have my wife observe when flushing. That will satisfy my paranoia. :-)

[CharSolera]

My problem with the vacumn breaker check valve isn't leaking water, it sometimes smells bad when I flush the toilet. If I tap on the valve, the smells disappear (for awhile). I understand a brass valve would be better quality. The first photo shows an anti siphon vacuumn breaker. Here's my question: Is "anti siphon" the same as "check valve" OR do I also need to add the brass check valve in the second photo?

[Duckogram]

CharSolera The issue you describe has nothing to do with the black tank flush water supply. The toilet has its own vacuum breaker anyway. Both of the vacuum breakers are there to prevent water from the black tank or toilet from backing up into your FW system or the fresh water supply.

As for the odor when flushing, you might look at your roof vent as a solution. You need to achieve negative pressure in the holding tank to keep in the stink. YMMV

[nomad297]

Originally Posted by CharSolera

My problem with the vacumn breaker check valve isn't leaking water, it sometimes smells bad when I flush the toilet. If I tap on the valve, the smells disappear (for awhile). I understand a brass valve would be better quality. The first photo shows an anti siphon vacuumn breaker. Here's my question: Is "anti siphon" the same as "check valve" OR do I also need to add the brass check valve in the second photo? Attachment 241695Attachment 241696

The difference between a standard brass “quality” check valve/atmospheric vacuum breaker like the one you show on the left and the plastic “cheap” check valve/atmospheric vacuum breakers designed for RVs is, the brass vacuum breakers will always allow some vapor/stink to escape the cap on the valve because there is nothing to seal the pipe between the black tank and the air inlet on the vacuum breaker. The vacuum breakers designed for RVs have a second check valve on the outlet side with a very light spring that will allow the water to drain down from the vacuum breaker by gravity, but will then close the opening once the water has drained, keeping the sewer gasses from escaping the tank at the flush outlet and exhausting out of the vacuum breaker cap. This is why when you tapped on the vacuum breaker, the smell would stop — that light spring just wasn’t strong enough to push that second check valve back into place, and when you tapped it, that second check valve was able to close.

I am not aware of any ASSE check valve/vacuum breakers with the second check valve on the outlet that will do what the RV type will do, but if we are going to get into ASSE approved check valves for this type of cross connection, a single-check atmospheric vacuum breaker would not fit the bill. We would be getting into reduced pressure zone backflow preventers.

So, if you want to keep the (minimal) protection and draining ability afforded by a check valve/vacuum breaker, you need to stick with the “cheap” type designed for RVs. Otherwise, you will be smelling your black tank through the cap of the brass one.

Bruce

[emm-dee]

I’m still looking for an explanation of how a flush fitting at the TOP of the black tank is going to get anything but air to backflow into the vertical line that leads to the incoming connection.

[bubbles]

Originally Posted by emm-dee

I’m still looking for an explanation of how a flush fitting at the TOP of the black tank is going to get anything but air to backflow into the vertical line that leads to the incoming connection.

Hang in there one of the retired master plumbers on this forum will have an answer for you.