RV News RVBusiness 2021 Top 10 RVs of the Year, plus 56 additional debuts and must-see units → ×


Closed Thread
 
Thread Tools Display Modes
Old 08-15-2019, 10:11 AM   #21
Senior Member
 
nomad297's Avatar
 
Join Date: Jul 2015
Posts: 5,696
Quote:
Originally Posted by Larry-NC View Post
One question: Does "waterlogged" mean that the rubber diaphragm fails catastrophically, or that the air just seeps away over time like a bicycle tire? My pressure is 70 psi after the PRV. I filled the tank to 35 psi. If it misbehaves, could I simply depressurize the water system and refill the tank to 35 psi? This is analogous to fixing water hammer by draining the system to get air back in the air hammer arrestors. Doing this every 10 years or so is not arduous. I'll probably do this and see how long it lasts before replacing the tank.
While working, if I happen to be near to an expansion tank while doing something else, I will always try to feel how heavy it is. If it is heavier than it should be, something is wrong with it. Either the air has leaked out of the bladder through the Schrader valve or the bladder has ruptured or developed a leak on the inside of the tank. To find out which happened, I push in the stem of the Schrader valve. If I get water, the bladder is ruined and the tank definitely needs to be replaced. If I get air or nothing at all, the bladder has leaked air out of the Schrader valve. I first measure the pressure of the water system, then drain the system to relieve the pressure, then pump the correct amount of air into the tank via the Schrader valve. Then I spray my gas leak detector onto the Schrader valve just to verify that it is leaking and how fast. I don’t carry replacement cores on my truck, so if tightening the existing core doesn’t take care of it, I replace the tank. I might as well in most cases, because, like I said before, they just don’t last very long, and I have tanks on my truck. If the tank is leaking at a weld or if it has developed pinholes (which is pretty common), there’s no doubt that it must be replaced.

Bruce
__________________
2016 Rockwood Windjammer 3029W Diamond
2015 Chevy 3500HD LTZ 6.0 Crew Cab 4x4 Long Bed 4.10:1 SRW
nomad297 is offline  
Old 08-15-2019, 11:52 AM   #22
Senior Member
 
Join Date: Jun 2013
Posts: 881
Quote:
Originally Posted by nomad297 View Post
There are very good reasons your RV may be equipped with backflow prevention devices. The device most discussed and frustrating to RV owners seems to be the vacuum breaker/check valve installed on the black water tank flush system. While sometimes problematic, these backflow preventers are necessary, and it is important to leave them in place if they are working, and replace them if they are leaking or not working as they should. No backflow preventer should ever be eliminated from a system or bypassed — they are there for a good reason, whether you understand their purpose, or not.

In another thread on this forum, I am being challenged to justify the purpose of one of these cross connection devices by somebody who has eliminated it from their black tank flush system. I’ve tried my best to explain the hazards involved with doing this, but this member and some others insist on pushing back and refusing to accept that the possibility of a hazard exists due to this modification. I am being asked to prove how backflow is possible in this situation. I would go blue in the face trying to provide all of the different possible scenarios to this member because he just doesn’t get it. But many people don’t get it.

Here are a couple of videos that might help people to understand the importance of backflow prevention devices and the hazards of cross connections. The first video is short and gives the basics. The second video is long (and old), but it will give people a much better understanding of how these things work and why they are so important.

Bruce

https://youtu.be/l5QoNSPpDZE

https://youtu.be/HLVt6GNxZho

stay your ground. I'm a mechanical contractor and fully understand the risks associated with reduced pressure backflow, it is very real.
nayther is offline  
Old 08-16-2019, 03:34 PM   #23
Senior Member
 
Join Date: Jan 2018
Location: Raleigh, NC
Posts: 3,568
Not the homeowner

Quote:
Originally Posted by tomkatb View Post
Many years ago I was involved with the backflow thing.

It became law in most areas to install said equipment on new homes and businesses. Few require the majority of homes in the US to install these devices.

So the majority do not have them. They need routine inspections which a licensed plumber must do. $300 a year?

Do all rv’s have backflow devices on the white water system? I do not remember seeing one on my fivers water line. Supposed to be near the connection to the hose. Where do I look?
At our built-in-1965 residence we had no choice. The city installed backflow preventers at the meter and threatened fines if they were tampered with. The 6-gallon water heater in the SOB travel trailer immediately started dripping from the T&P valve. This covered every meter in the city, something I would call the "majority of homes." Since the city makes the rules, I am guessing there is no inspection schedule.

At our campground, the owner put the preventers on the hose bibbs at the water pedestal and forbids their removal.

As for your fiver, look at the campground water pedestal. If there's a brass fitting that seems to serve no useful purpose except as an extender (about 1") to the hose bibb, that's one form of backflow preventer.

Does your fiver have a separate hose connection for a black-tank flush? If so, there is an additional backflow preventer (vacuum breaker) inside the trailer. It will be near the black tank, but above it, at least 10-18" or so, and near the flush hose inlet. Look for a loop of pipe coming up through the floor and then down to the hose inlet. At the top of the loop, one corner has an elbow and the other has a tee. The vacuum breaker is at the top of the tee. This could be in a cabinet beneath the lavatory sink or elsewhere. Maybe something behind a screwed-on panel.
__________________
Larry

Sticks and Bricks: Raleigh, NC
2008 Cherokee 38P: at Ivor, VA permanently
Larry-NC is offline  
Old 08-19-2019, 04:33 AM   #24
Senior Member
 
Join Date: Sep 2018
Location: Sarasota florida
Posts: 147
I got a nice pair of jugs!

From Walmart that are square and nest for transport. 3 gallons each and refills are $1.12. It’s reverse osmosis water that is uv treated as well. That’s what goes in my water tank unless I have a city water source. Even then, the “boil water notice” comes out the day after you left that campground. Years living in boats have taught me that eventually your “fresh” water tank will get funky. This all started when, after a hard rain, the water at a favorite campsite turned burnt orange color.
Attached Thumbnails
Click image for larger version

Name:	7131939E-80C4-4B9A-9C51-5CA68A61BF56.jpg
Views:	44
Size:	237.0 KB
ID:	212845  
Papadave is offline  
Old 08-29-2019, 10:05 PM   #25
Senior Member
 
Join Date: Sep 2017
Posts: 135
Quote:
Originally Posted by nomad297 View Post
There are very good reasons your RV may be equipped with backflow prevention devices. The device most discussed and frustrating to RV owners seems to be the vacuum breaker/check valve installed on the black water tank flush system. While sometimes problematic, these backflow preventers are necessary, and it is important to leave them in place if they are working, and replace them if they are leaking or not working as they should. No backflow preventer should ever be eliminated from a system or bypassed — they are there for a good reason, whether you understand their purpose, or not.

In another thread on this forum, I am being challenged to justify the purpose of one of these cross connection devices by somebody who has eliminated it from their black tank flush system. I’ve tried my best to explain the hazards involved with doing this, but this member and some others insist on pushing back and refusing to accept that the possibility of a hazard exists due to this modification. I am being asked to prove how backflow is possible in this situation. I would go blue in the face trying to provide all of the different possible scenarios to this member because he just doesn’t get it. But many people don’t get it.

Here are a couple of videos that might help people to understand the importance of backflow prevention devices and the hazards of cross connections. The first video is short and gives the basics. The second video is long (and old), but it will give people a much better understanding of how these things work and why they are so important.

Bruce

https://youtu.be/l5QoNSPpDZE

https://youtu.be/HLVt6GNxZho
You can explain things to people but you can't comprehend it for them.
imjustdave is offline  
Old 07-19-2020, 06:40 AM   #26
Senior Member
 
nomad297's Avatar
 
Join Date: Jul 2015
Posts: 5,696
It is time to bring this thread back to life as there are a couple of active threads right now where the information here needs to be learned.

Do not eliminate or bypass the check valve/vacuum breaker for your black tank flush system. You could kill somebody.

Bruce
__________________
2016 Rockwood Windjammer 3029W Diamond
2015 Chevy 3500HD LTZ 6.0 Crew Cab 4x4 Long Bed 4.10:1 SRW
nomad297 is offline  
Old 10-09-2020, 08:46 AM   #27
Senior Member
 
nomad297's Avatar
 
Join Date: Jul 2015
Posts: 5,696
With the crazy amount of new RVers out there this year and the large number of new threads being posted about the black tank flush and the backflow device used for them, I thought it would be a good idea to get this thread back up where people might appreciate it.

Bruce
__________________
2016 Rockwood Windjammer 3029W Diamond
2015 Chevy 3500HD LTZ 6.0 Crew Cab 4x4 Long Bed 4.10:1 SRW
nomad297 is offline  
Old 10-09-2020, 03:03 PM   #28
Senior Member
 
Join Date: Jul 2017
Location: California
Posts: 7,616
https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Works great...doesn't leak. Put a backflow preventer on your hose.

I know people that have soft floors because of these black plastic pieces of junk leaking.
babock is offline  
Old 10-09-2020, 03:40 PM   #29
Senior Member
 
nomad297's Avatar
 
Join Date: Jul 2015
Posts: 5,696
Quote:
Originally Posted by babock View Post
Put a backflow preventer on your hose.
Which ASSE Standard backflow preventer is suitable and approved for use for such a hazardous cross connection situation that will attach to a hose? Surely you know since you are advocating the use of such a device.

Bruce
__________________
2016 Rockwood Windjammer 3029W Diamond
2015 Chevy 3500HD LTZ 6.0 Crew Cab 4x4 Long Bed 4.10:1 SRW
nomad297 is offline  
Old 10-09-2020, 03:54 PM   #30
Member
 
Join Date: Jul 2020
Posts: 38
Quote:
Originally Posted by nomad297 View Post
There are very good reasons your RV may be equipped with backflow prevention devices. The device most discussed and frustrating to RV owners seems to be the vacuum breaker/check valve installed on the black water tank flush system. While sometimes problematic, these backflow preventers are necessary, and it is important to leave them in place if they are working, and replace them if they are leaking or not working as they should. No backflow preventer should ever be eliminated from a system or bypassed — they are there for a good reason, whether you understand their purpose, or not.

In another thread on this forum, I am being challenged to justify the purpose of one of these cross connection devices by somebody who has eliminated it from their black tank flush system. I’ve tried my best to explain the hazards involved with doing this, but this member and some others insist on pushing back and refusing to accept that the possibility of a hazard exists due to this modification. I am being asked to prove how backflow is possible in this situation. I would go blue in the face trying to provide all of the different possible scenarios to this member because he just doesn’t get it. But many people don’t get it.

Here are a couple of videos that might help people to understand the importance of backflow prevention devices and the hazards of cross connections. The first video is short and gives the basics. The second video is long (and old), but it will give people a much better understanding of how these things work and why they are so important.

Bruce

https://youtu.be/l5QoNSPpDZE

https://youtu.be/HLVt6GNxZho
You might as well give up. People on TT forums are WAY smarter then engineers. I read one yesterday where a guy is smarter then the weight stickers on trucks.
boydn1 is offline  
Old 10-09-2020, 04:08 PM   #31
Senior Member
 
Join Date: May 2019
Posts: 525
Quote:
Originally Posted by nomad297 View Post
Which ASSE Standard backflow preventer is suitable and approved for use for such a hazardous cross connection situation that will attach to a hose? Surely you know since you are advocating the use of such a device.

Bruce
Are you calling that plastic junk check valve a “backflow preventer”.


A reduced pressure backflow preventer is a true backflow device. Even a double check assembly doesn’t meet commercial plumbing code for potable water.


The only way you could backflow the black tank rinse is if the city main broke, and cause a vacuum WHILE you were overflowing the the black tank through the vent on the roof, which would take approximately 16 psig of water pressure to push to the roof.
__________________
2019S Mod Thread
https://www.forestriverforums.com/fo...ad-184896.html

2020 Rockwood Mini Lite 2109S
2017 GMC 2500HD Denali 6.6L Duramax
01tundra is offline  
Old 10-09-2020, 04:14 PM   #32
Senior Member
 
Homebrew's Avatar
 
Join Date: Sep 2014
Posts: 970
Quote:
Originally Posted by 01tundra View Post
Are you calling that plastic junk check valve a “backflow preventer”.


A reduced pressure backflow preventer is a true backflow device. Even a double check assembly doesn’t meet commercial plumbing code for potable water.


The only way you could backflow the black tank rinse is if the city main broke, and cause a vacuum WHILE you were overflowing the the black tank through either the toilet valve or vent on the roof, which would take approximately 16 psig of water pressure to push to the roof.


It can’t be junk ! We all have them and no complaints so far and no problems reported.
__________________
XLR Thunderbolt 300X12HP
2014 Ram 3500 DRW
Homebrew is offline  
Old 10-09-2020, 04:20 PM   #33
Senior Member
 
Join Date: May 2019
Posts: 525
Quote:
Originally Posted by Homebrew View Post
It can’t be junk ! We all have them and no complaints so far and no problems reported.
I’ve read of several failures of these plastic flap style check valves.
__________________
2019S Mod Thread
https://www.forestriverforums.com/fo...ad-184896.html

2020 Rockwood Mini Lite 2109S
2017 GMC 2500HD Denali 6.6L Duramax
01tundra is offline  
Old 10-09-2020, 04:34 PM   #34
Senior Member
 
nomad297's Avatar
 
Join Date: Jul 2015
Posts: 5,696
Quote:
Originally Posted by 01tundra View Post
Are you calling that plastic junk check valve a “backflow preventer”.
Yes, I am. And yes, it is.

Quote:
Originally Posted by 01tundra View Post
A reduced pressure backflow preventer is a true backflow device. Even a double check assembly doesn’t meet commercial plumbing code for potable water.
An RPZ backflow preventer has its place (where there is positive pressure on both sides of it), but not in an RV and not in a situation where an air gap is required. Double check valves most certainly are are approved for use with potable water in commercial (and residential) situations. It all depends on what it is to be used for.

Quote:
Originally Posted by 01tundra View Post
The only way you could backflow the black tank rinse is if the city main broke, and cause a vacuum WHILE you were overflowing the the black tank through either the toilet valve or vent on the roof, which would take approximately 16 psig of water pressure to push to the roof.
There are many more situations than just a main break that can cause negative pressure to draw/siphon water out of the black tank. There are many people who fill their tanks to above the level of the flush inlet. It can happen very easily. I’m not understanding what you are trying to say regarding the 16psi to push water to the roof and what that would have to do with anything.

Bruce
__________________
2016 Rockwood Windjammer 3029W Diamond
2015 Chevy 3500HD LTZ 6.0 Crew Cab 4x4 Long Bed 4.10:1 SRW
nomad297 is offline  
Old 10-09-2020, 04:35 PM   #35
Senior Member
 
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 10,418
Quote:
Originally Posted by 01tundra View Post
I’ve read of several failures of these plastic flap style check valves.
I too have read about failures but I'm beginning to think my TT is a "Unicorn".

I haven't had any issues with my black tank backflow preventer, my onboard water filter hasn't leaked (or canister broken). my Castle Rock tires went almost 20 K miles before I replaced them I carry my generator on the back bumper (with Safe T Struts and Genny Go platform) and haven't had the bumper fail.


With the backflow preventer I do use a dedicated hose (bright orange) for flushing the tank. I shut off water at the spigot and then remove the hose from the flush connector first. This lessens the chance of any water flowing back into the hose should the BFP be defective. I then open the spigot, flush the hose, remove, drain, and store.

As for "soft floor", I DO check around the BFP after every use to see if there is any leakage. I choose not to wait until I end up with rotten flooring.

Over three years now and not a drop. Like I said, apparently I got a Unicorn
__________________
"A wise man can change his mind. A fool never will."

"You only grow old when you run out of new things to do"

2018 Flagstaff Micro Lite 25BDS
2004 Nissan Titan
TitanMike is online now  
Old 10-09-2020, 04:42 PM   #36
Senior Member
 
Homebrew's Avatar
 
Join Date: Sep 2014
Posts: 970
You know your back flow device is working on you washer and sewage connection when the water sprays out of the connection with pressure when disconnecting the hose.
If this doesn’t happen you have a bad back flow device.
__________________
XLR Thunderbolt 300X12HP
2014 Ram 3500 DRW
Homebrew is offline  
Old 10-09-2020, 04:58 PM   #37
Senior Member
 
Join Date: May 2019
Posts: 525
Quote:
Originally Posted by nomad297 View Post
Yes, I am. And yes, it is.



An RPZ backflow preventer has its place (where there is positive pressure on both sides of it), but not in an RV and not in a situation where an air gap is required. Double check valves most certainly are are approved for use with potable water in commercial (and residential) situations. It all depends on what it is to be used for.



There are many more situations than just a main break that can cause negative pressure to draw/siphon water out of the black tank. There are many people who fill their tanks to above the level of the flush inlet. It can happen very easily. I’m not understanding what you are trying to say regarding the 16psi to push water to the roof and what that would have to do with anything.

Bruce
As long as you have at least 16 psig of pressure on the flush it is physically impossible to backflow because it would be coming out of the roof vent instead.

A double check in commercial domestic water applications is not acceptable per the IPC.

And what you’re referring as a backflow preventer is indeed vacuum breaker, these both do the same thing -

Mueller FBA_108-904RP 108-904RP Backflow Preventer-Vacuum Breaker https://www.amazon.com/dp/B000DZHA7S..._JipGFbKPNYYPT

Camco Vacuum Breaker Assembly - Protects Your Water Supply from Harmful Pollutants and Contaminates (40395) https://www.amazon.com/dp/B07P75Y1MR..._TmpGFbG93Z24M
__________________
2019S Mod Thread
https://www.forestriverforums.com/fo...ad-184896.html

2020 Rockwood Mini Lite 2109S
2017 GMC 2500HD Denali 6.6L Duramax
01tundra is offline  
Old 10-09-2020, 05:08 PM   #38
Senior Member
 
nomad297's Avatar
 
Join Date: Jul 2015
Posts: 5,696
Quote:
Originally Posted by 01tundra View Post
As long as you have at least 16 psig of pressure on the flush it is physically impossible to backflow because it would be coming out of the roof vent instead.
Ok. Well, first, at what would be roughly 8-9’ from the bottom of the tank to the top of the vent, you would have approximately 4psi at the bottom of the tank. For every foot of elevation, the water pressure increases by just less than 1/2psi. But that’s not what this discussion is about. I am not talking about pressure pushing the water back through the hose. But I think you know that.

Bruce
__________________
2016 Rockwood Windjammer 3029W Diamond
2015 Chevy 3500HD LTZ 6.0 Crew Cab 4x4 Long Bed 4.10:1 SRW
nomad297 is offline  
Old 10-09-2020, 06:50 PM   #39
Senior Member
 
Join Date: May 2019
Posts: 525
Quote:
Originally Posted by nomad297 View Post
Ok. Well, first, at what would be roughly 8-9’ from the bottom of the tank to the top of the vent, you would have approximately 4psi at the bottom of the tank. For every foot of elevation, the water pressure increases by just less than 1/2psi. But that’s not what this discussion is about. I am not talking about pressure pushing the water back through the hose. But I think you know that.

Bruce
You can save the pseudo plumbing education, I fully understand how it all works and both the vacuum breakers I posted achieve the same thing - protecting the water supply.
__________________
2019S Mod Thread
https://www.forestriverforums.com/fo...ad-184896.html

2020 Rockwood Mini Lite 2109S
2017 GMC 2500HD Denali 6.6L Duramax
01tundra is offline  
Old 10-09-2020, 06:51 PM   #40
Site Team
 
wmtire's Avatar
 
Join Date: Nov 2010
Location: Northeast Louisiana
Posts: 25,096
Thread closed.
__________________
2011 Flagstaff 831 RLBSS

I often say to myself, "I can't believe that cloning machine worked."
wmtire is online now  
Closed Thread

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by Forest River, Inc. or any of its affiliates. This is an independent, unofficial site.



All times are GMT -5. The time now is 12:07 PM.