Fresh Tank to Black Tank Flush (Spray)

[withidl]

Tiring of hooking up a separate hose to the black tank flush (spray) connector when dumping, I procured from my local hardware store a stainless steel braided hose and brass fittings so that I could semi-permanently connect the adjacent fresh water faucet with the black tank flush connector (see photos).

Now when I dump the black tank all I have to do is turn on the onboard pump (having sufficient fresh water on board), connect the slinky, pull the black tank valve and then open the fresh water faucet to spray flush the black tank while dumping.

[A W Warn]

I know there is a factory installed backflow preventer inside already, but I would install another in this line. Don't think I would take a chance on backflow into the fresh water system!

The water line is reduced from 1/2" to 1/4". Do you think you are getting adequate flow/pressure to spray the tank clean?

[Bluto]

2 things come to mind when I viewed this. First is there enough pressure to run the black rinse properly to do a god job of rinsing the tank?
Next it looks like there could be a chance of fresh water contamination.
Not really sure if either is a valid concern. I'd like to here if you considered those potential problems, and how well does this work for you?

[Bluto]

A W Warn,
It looks like you beat me to the draw. I'm a slow typer. But we are both thinking the same way.

[withidl]

Originally Posted by A W Warn

I know there is a factory installed backflow preventer inside already, but I would install another in this line. Don't think I would take a chance on backflow into the fresh water system!

The water line is reduced from 1/2" to 1/4". Do you think you are getting adequate flow/pressure to spray the tank clean?

I installed this over 6 years ago and did consider the potential of backflow past the preventer. The faucet provides a 2nd backflow preventer and I never open it unless the pump is on providing positive pressure. Additionally, the fresh water is chlorinated.

As to the reduction of the water line; the short distance doesn't seem to allow for any appreciable loss of flow and like the nozzle on a garden hose the flush spray nozzle offers a restriction and turbulence of flow in doing its job. I’ve had no trouble with flushing.

[Melody Ranch]

Please don't offer me a drink of water. Every time you operate that faucet you are opening a direct link,,,,toilet to fresh water tank.

[DaveFL]

Is there is a back flow preventer installed where I can't see it on mine? When I put outside pressure to the hose fitting I get it running out on disconnecting. That would indicate to me no backflow preventer upstream or it is not working as it would be sqirting out somewhere upstream.

[withidl]

Originally Posted by DaveFL

Is there is a back flow preventer installed where I can't see it on mine? When I put outside pressure to the hose fitting I get it running out on disconnecting. That would indicate to me no backflow preventer upstream or it is not working as it would be sqirting out somewhere upstream.

Basis the A/S Owners Manual, the following is the plumbing inlet order:

Water hose connector > 1/2" Tubing > Vacuum Breaker > Check Valve > 1/2" Tubing > Spray Head.

The run-out you get on disconnecting is due to the "Vacuum Breaker" allowing the line between the check valve and the inlet to drain so that in cold weather water is not retained in the tubing to freeze and break.

[DaveFL]

Originally Posted by withidl

Basis the A/S Owners Manual, the following is the plumbing inlet order:

Water hose connector > 1/2" Tubing > Vacuum Breaker > Check Valve > 1/2" Tubing > Spray Head.

The run-out you get on disconnecting is due to the "Vacuum Breaker" allowing the line between the check valve and the inlet to drain so that in cold weather water is not retained in the tubing to freeze and break.

Thanks I don't have that detailed OM to show it.
I have thought about doing what you did, especially when the only water available is in a hose without a threaded end. Knowing A/S didn't forget to include a vacuum break will also make me feel better when I hook it up at home. I will take your hookup and add another point to hook in a hose from an outside source, without having to disconnect your built in hose, using a three way valve.

[Gringo]

our flush fitting is up high on the side of the trailer, above the external water connection. I am thinking in my case it would make more sense to just buy a "Y" fitting and a short length of hose, so I could divert the incoming water from the main supply to either direction, plumbing or spray.

[A W Warn]

Originally Posted by Melody Ranch

Please don't offer me a drink of water. Every time you operate that faucet you are opening a direct link,,,,toilet to fresh water tank.

That is my thought too. And, since the fresh water tank is below the hookup for the black tank flush, guess which way the siphoning goes if there is any leak in the backflow preventer!

[thecatsandi]

Convient but not a good idea. Possibility of cross contamination. Not good. There should be a short piece of hose to connect to the black tank flush.

[SoCalStreamr]

Im fecal phobic and this makes me want to scream. Maybe I'm too sensitive. Maybe you cant be careful enough. I like to think my thirdhand AS is uber clean...

EDIT: "Honey I'll clean all the rest of the AS if you do "poop duty" for 2 minutes."

[Rebee]

I was concerned about the back flow issue as well, so I went to a garden hose quick disconnect. I put the end with the valve on the bulkhead side where the sprayer unit and the other end to the spigit. I can turn off any back wash while the water is still on and then close the faucet and remove the quick disconnect. No screwing the fitting on just push on like an air hose. Can not provide pictures, baby is at base camp right now.

[DaveFL]

Originally Posted by Melody Ranch

Please don't offer me a drink of water. Every time you operate that faucet you are opening a direct link,,,,toilet to fresh water tank.

Not quite direct link, BUT possible cross contamination.
I just put in a new toilet and looking at the connections water comes out high and free flows into the bowl, no chance of back flow contamination unless the toilet overflows and crosscontamination would be guaranteed if outflow was submerged with no pressure in the waterline. So back to the original fine design, with pressure in the freshwater system with working backflow preventers, shutoff valves off when they are not being used and adding chlorine to the tank and drinking bottled water never a problem, much less of a problem than hooking up to a system at a park that isn't providing safe water. In the USA we take for granted the faucet has potable water, after all the parks usually have a sign near the dump station saying flush water is not for drinking. (Except at Alum Creek, Columbus Ohio state park where they want you to fill at the dump site and don't provide faucets at the campsites.)
The black tank is isolated from the the supply line, it is even isolated from the grey tank until you change your system. This is a design for the convenience of the person in charge of doing a less
desireable chore not for the passengers enjoying the system.
PS. Drinking water in most A/S is from a separate faucet with filter fitted.
Safe travels.

[silversled]

Considering the seriousness of the health risk assoicated contamination of the water, I can understand everyone's response. Everyone has a different risk evaluation process.

My question would be: how do you know your check value is operating correctly? This device, a single device, is your insurance to prevent bateria entering your water supply and potentially sending you to the hospital and/or killing you. Is it worth the convienience when a single point failure of the check value puts you at serious risk? But not just you, but anyone who drinks water on your trailer, potentially children who do not have a developed immune system?

Just food for thought.

[TxToaster]

We have a '92 and on ours we have both the inlet and outlet. not to take the thread in a different direction, but the pictures are essentially what is on ours, except both the inlet and outlet are mounted on the front of the box. How is the factory installation designed to work? I get the picture of the water going into the tank. Does it somehow feed a high pressure sprayer system? Are there multiple sprayers, or just one? Also, what is the purpose of the outlet nozzle with the valve? I'm not sure I would want to experiment to see what comes out of that? Thanks, in advance for solving a two year mystery.

[A W Warn]

TxToaster,

If you have a flush system, there should be three hookups. One fresh water inlet, one outlet hose bib, and one inlet for the flush system.

The "black tank flush" system should be described in your owners manual, along with a drawing of the system. In my excella it's a multi-hole spray head inside the black tank, a pipe loop up to a backflow preventer, then a vacuum breaker, then a pipe down to the inlet. This system is supposed to eliminate backflow/siphoning, but I tend to lean toward caution! I carry a second hose for flushing, which never use for fresh water.

The system in mine is manufactured by No-Fuss Flush. You can find more info online.

[TxToaster]

Originally Posted by A W Warn

TxToaster,

If you have a flush system, there should be three hookups. One fresh water inlet, one outlet hose bib, and one inlet for the flush system.

The "black tank flush" system should be described in your owners manual, along with a drawing of the system. In my excella it's a multi-hole spray head inside the black tank, a pipe loop up to a backflow preventer, then a vacuum breaker, then a pipe down to the inlet. This system is supposed to eliminate backflow/siphoning, but I tend to lean toward caution! I carry a second hose for flushing, which never use for fresh water.

The system in mine is manufactured by No-Fuss Flush. You can find more info online.

Mine only has 2 hookups, so now I'm really not sure what this arrangement is.
http://www.airforums.com/attachments...6/pict2148.jpg

The white tube in the background is the routing of the 2nd AC condensation line.

[ROBERT CROSS]

Originally Posted by DaveFL

Is there is a back flow preventer installed where I can't see it on mine? When I put outside pressure to the hose fitting I get it running out on disconnecting. That would indicate to me no backflow preventer upstream or it is not working as it would be sqirting out somewhere upstream.

http://www.airforums.com/forums/f443...ion-50222.html

Mine was under the bathroom sink.....LEAKING!!