Secret to blank tank flush?

[Forester Fred]

Is there some other step necessary to get the black tank flush to work?

I tried mine for the first time today.....and quickly found out that the quality control people at FR were sleeping on the job. I had water squirting all over the inside of my bathroom cabinet. The tank flush line comes through the wall from the outside inside the cabinet with a white flexible hose. The guys at the factory didn't tighten the fitting on what I'm assuming is the check valve, black plastic thing that the white hose goes in to and has a blue pex line coming out and running parallel to the white line before disappearing through the base of the cabinet to where the black tank is.

I tightened the connection on the incoming hose to what I'm assuming is the check valve, cleaned up all the spilled water and tried again.....nothing. No water went into the tank. I kept the toilet open so I could see so I know there was no back pressure on the system - nothing.

What else do I need to do? (I also posted this on an older thread, sorry for starting a new one, I didn't know if anyone would see the old one or not.)

[Happy Vibe]

They may have put the check valve in backwards (should be an arrow on it , I think) or the the valve is bad.

[dieselguy]

The valve you are talking about is a vacuum breaker ... they are put on to keep possible siphoning of water back into the supply faucet. They often fail and make a real mess due to spraying water all over. It is possible that the nozzle is plugged up in you tank from a bad install.

[OldCoot]

IMO, the best thing to do is go to Lowes/HD and get a quality back flow preventer valve and hook it directly to the inlet (inside the trailer) and disconnect the stuff the factory installed and re-route the inlet directly to the flush line and throw the factory stuff in the garbage.

[Forester Fred]

This is what I'm referring to -

The white water line goes through the wall to the outside fitting, the blue pex goes from the top down to the tank



This photo is looking up at the underside of the bathroom vanity top.
This is where the white water line and blue pex meet with the valve/back flow preventer/vacuum breaker or whatever it's called.



This is the valve/back flow preventer/vacuum breaker. The white water line fitting was loose and this is where it sprayed water from all over. Once I tightened the fitting up nothing happened when I turned the water on to the outside fitting.



If the mechanism in the tank is bad how would the dealer replace it? Do they need to drop the black water tank?

[dieselguy]

It could be that the blue line is simply kinked shut below. As far as I know ... you would have to at least have access to the flush fitting on the side of the tank to remove the hose and see if construction debris has packed inside. Whether this includes dropping the tank depends on your rigs construction.

[Forester Fred]

I did some more research. My water inlets are B&B products. I found this on their website:


What they are calling ATMOSPHERIC VACUUM BREAKER/ CHECK VALVE is what I'm seeing under my vanity top. I guess the good news is that if that needs replacement it's fairly easy. Everything has a pex crimp clamp on it so just taking the hoses off to see if they're blocked looks to be a pain. The good news is that my camper is less than 4 months old so it's still under warranty. It's a PITA to take it back to the dealer as the closest dealer for Forester is 100 miles away, but they can figure it out and pay for it.

Edit - WOW - just found out the check valve is $50....this is definitely a warranty issue!

For anyone else, here's a link to the PDF with the installation instructions. It might help someone off warranty troubleshoot: http://www.bandbmolders.com/files/Th...2_Install_.pdf

[bob caldwell]

Did the same as OC suggested.....mine was starting to leak from the inside plastic valve that's supposed to shut off the vent part when water pressure is applied. Got rid of this valve and, on mine, 15' of white hose.

[MOODMAN]

The check valve is there by code, but IMHO, isn't absolutely necessary. Throw it away, put in a short piece of pipe, reclamp it, and try it again.

[itat]

If you're going to connect to a potable water supply, it's absolutely necessary for the safety of the water supply.

I have an external plastic backflow preventer/vacuum break/check valve that I've been using for our black tank flush hose (got it for free from the RV dealer). I haven't looked to see if there's one inside but I expect there would be. I just like the safety of knowing for sure that I'm using one.

On our last camping trip I connected the plastic valve and hose to the flusher inlet and the high water pressure blew the plastic check valve apart. I need to pickup a brass check valve and then try to see what the plumbing is like inside.

Is this what I should be looking for?
Aquadynamic | Vacuum Breaker 3/4 Inch Brass | Home Depot Canada
or this
8 Hose Connection Vacuum Breakers, Brass, Vacuum Breakers, Backflow Prevention - Watts Canada

I'll probably pick up a basic pressure reducer too because we camp at that campground every year.

[hilitephoto]

Just had the same thing happen to my '16 Columbus. Only behind the shower faucets. Just not tightened at factory.

[Forester Fred]

I got the camper home today and tried again. I thought I might have goofed as the first time I tried using the tank flush the black tank was 2/3rds full and the camper was parked on an incline so the nose was about 8 to 10 inches higher than the rear. I thought that I might have covered the sprayer with water and that's why I didn't see anything happening through the toilet.

When I tried it today I did it on an empty black tank. Nothing - I shut the water off and when I unscrewed the hose from the fitting on the side of the camper I got air pressure coming back out of the connection. This leads me to believe something in there - the valve? - is blocking the mechanism.

[bob caldwell]

I. went with a back flow protector, 3/4" brass that has 2 back flow flaps inside, made to be used in a house.Don't need vacumn break as tank is vented thru roof. Also, when the plastic unit fails, you'll have water everywhere and if the vac. part fails, it'll stink up the joint. The valve I got was just at $30.00....worth it to me. Check the valve for correct flow direction..,.water should inter from bottom and exit the side....in the side outlet there is a spring loaded check valve that water pressure opens, allowing water out the side connection...if hooked up backward, no flow. Also, the little rectangular top piece is removable to look inside.

[mnoland30]

It doesn't happen often, but if someone opened a fire hydrant or broke a main while you were cleaning your blackwater tank, the huge flow out of the hydrant or break would cause a vacuum on your hose and suck black water into the fresh water system. Black water contains e-coli bacteria, which can be fatal.
That is why backflow prevention is required by code and regulation. Would you take the risk to save $30. I wouldn't. I'm thinking a wand on the end of a hose would do a better job of cleaning the tank anyway.

[Forester Fred]

Originally Posted by bob caldwell

I. went with a back flow protector, 3/4" brass that has 2 back flow flaps inside, made to be used in a house.Don't need vacumn break as tank is vented thru roof. Also, when the plastic unit fails, you'll have water everywhere and if the vac. part fails, it'll stink up the joint. The valve I got was just at $30.00....worth it to me. Check the valve for correct flow direction..,.water should inter from bottom and exit the side....in the side outlet there is a spring loaded check valve that water pressure opens, allowing water out the side connection...if hooked up backward, no flow. Also, the little rectangular top piece is removable to look inside.

Bob, could you post a link or image of the back flow protector you got?

Thanks

[nomad297]

A very popular and not so expensive dual check backflow preventer is the Watts No.7.

Bruce

[bob caldwell]

That be it!

[bob caldwell]

Originally Posted by mnoland30

It doesn't happen often, but if someone opened a fire hydrant or broke a main while you were cleaning your blackwater tank, the huge flow out of the hydrant or break would cause a vacuum on your hose and suck black water into the fresh water system. Black water contains e-coli bacteria, which can be fatal.
That is why backflow prevention is required by code and regulation. Would you take the risk to save $30. I wouldn't. I'm thinking a wand on the end of a hose would do a better job of cleaning the tank anyway.

Tanks are vented...can't create vacumn.

[Forester Fred]

I just checked, the L7 is listed as "obsolete" on the Watts website. That's the bad news...the good news is it looks like they've replaced it with the LF7 (lead free)
LF7 Lead Free* Bronze Dual Check Valves, Dual Checks / Dual Checks with Atmospheric Vent, Backflow Prevention - Watts

Description:
Series LF7 Lead Free* Dual Check Valves prevent the reverse flow of polluted water from entering into the drinking water supply at the service entrance or at individual outlets. It consists of a Lead Free* cast copper silicon alloy body construction, with two plastic replaceable check valves, and stainless steel springs. Series LF7 is designed for non-health hazard residential water system containment, continuous pressure applications. It is installed immediately downstream of the residential water meter, in a vertical or horizontal position. Check with local inspection authorities for installation requirements. Minimum Working Pressure: 10psi (69 kPa) Maximum Working Pressure: 150psi (10 bar).

[bob caldwell]

Two hose nipples and clamps also needed