B&B Model 571

[Paqman57]

Originally Posted by emm-dee

Mine started leaking after the third tank flush. Fortunately the water only got on a “non-wood” area and drained outside. As I’ve done with two previous units this is a guaranteed permanent fix:

Great idea. I pulled mine out and replumbed it under the side of the trailer. Don't know why they don't just put a check valve on the line so it can't back flow into the fresh water system.

[rockfordroo]

Originally Posted by Budman2082

Took photo but can’t figure out how to display it. 571 is inside wall with a 4 inch round opening. Lucky to get one hand in there. Forget about trying to loosen or tighten fittings.

Looks like emm-dee got to his through a 4" round opening (see his pic in Post #19).

For posting pics, see post #7 of this published how-to thread ==> http://www.forestriverforums.com/for...sics-6778.html.

[emm-dee]

Originally Posted by Paqman57

Great idea. I pulled mine out and replumbed it under the side of the trailer. Don't know why they don't just put a check valve on the line so it can't back flow into the fresh water system.

There is no way anything can flow back to the fresh water system. The line that had the B&B valve runs across from the utility bay on the left side of the MH then goes up about three feet or so, through the valve and then down to it’s termination point on top of the black tank. The fresh water tank is above the black tank and there is no sort of connection between the two.

[Paqman57]

Originally Posted by emm-dee

There is no way anything can flow back to the fresh water system. The line that had the B&B valve runs across from the utility bay on the left side of the MH then goes up about three feet or so, through the valve and then down to it’s termination point on top of the black tank. The fresh water tank is above the black tank and there is no sort of connection between the two.

I'm talking about the fresh/public water that is being used to flush out the tank. It's the same reason there is now a vacuum break valve on outdoor faucets, to keep something being sucked back into the water system through a garden hose.

[emm-dee]

If you connect a garden hose to a water faucet that has 30-80 psi water pressure just how is anything going to move from the hose BACKWARDS into the faucet? Plus, the hose outlet is never submerged into anything and the only thing that can flow toward the faucet is air.

[orabun]

I've got a 2005 FR Cardinal that I can't find the Back flow valve. The house connection for the black tank flush is on the driver side but the toilet and bathroom sink is on the passenger side. It goes up behind the shower but I can't get to it. The problem I'm having is I can't get any water to go through the black water tank to flush out the tank. Any help would be greatly appreciated. I put a post about this on here before but didn't get a good answer to my problem, but I may not have ask the right question.

[woo10-210]

Originally Posted by emm-dee

If you connect a garden hose to a water faucet that has 30-80 psi water pressure just how is anything going to move from the hose BACKWARDS into the faucet? Plus, the hose outlet is never submerged into anything and the only thing that can flow toward the faucet is air.

If you have the garden hose connected to the black tank flush with the hose bib valve open and the pressure suddenly stopped, the hose could suck black water back into the fresh water supply without the check valve.
Probably a rare event on a municipal water supply but imagine what could happen if your home water supply is off of a well and you incur a power outage.

[koller1509]

Originally Posted by woo10-210

If you have the garden hose connected to the black tank flush with the hose bib valve open and the pressure suddenly stopped, the hose could suck black water back into the fresh water supply without the check valve.
Probably a rare event on a municipal water supply but imagine what could happen if your home water supply is off of a well and you incur a power outage.

Only if your black tank was completely full. Otherwise the waste water level is below backflush nozzle.

[emm-dee]

Originally Posted by woo10-210

If you have the garden hose connected to the black tank flush with the hose bib valve open and the pressure suddenly stopped, the hose could suck black water back into the fresh water supply without the check valve.
Probably a rare event on a municipal water supply but imagine what could happen if your home water supply is off of a well and you incur a power outage.

Losing power is irrelevant in this case. There is still a 50-80 gallon pressure tank that would have to fail, and even if it did there’s a lot of water that would have to drain out somewhere before a vacuum could be created that was sufficient enough to start drawing from the black tank. What are the odds of all that happening simultaneously.

Bottom line is if all that happened AND the operator was stupid enough to leave the area during the fill process then they pretty much deserve whatever happens. That’s why there are instructions printed on shampoo bottles.

On the other hand, the odds of the cheap 571 valve leaking water are high in favor of failing.