Black tank flush issue

[tinstartrvlr]

Emptied the black tank today and did as I usually do, hooked up the garden hose to the flush connector and turned it on. The tank had drained to near empty when I turned it on. Lo and behold, the water was not going into the tank as it is supposed to, but was apparently spraying out the vent under the bathroom sink. I found this out when I saw water dripping from the belly while I was outside, and when I went inside and looked under the sink, the vent and most everything around it was quite wet. It had no smell so I know it was fresh water.
Anyone know why it did that, and how do I fix it?

[tinstartrvlr]

Update.... today I had a friend turn on the water while I watched the check valve/connections etc under the sink. This time, no leak. Not a drop. Quite a change from the other day when water was pouring out the bottom of the camper. I could hear the flush spraying in the black tank like it should. Still going to replace the valve, but really puzzled as to why I had the problem in the first place. :h

[Lynnmor]

tinstartrvlr wrote:
"From the manufacturer:
Vac/Check cannot be installed in an inaccessible location where venting of water from device during normal operation causes damage. It must be installed in an easily accessible location to end user."

Venting of water? Do they mean when it fails? I thought it should only have air going through it normally. Guess they dropped the ball on mine; its under the sink (easily accessible) and when it decided to malfunction, the floor and everything below it got wet. Think the damage will be evident someday.

No, they don't mean when it fails. Under certain conditions water is expelled as a normal part of its operation, and the RV manufacturers cannot read.

Another clue from their website:

ATMOSPHERIC VACUUM BREAKER/
CHECK VALVE
(571 Vac Chk) must be 6” above flood
rim of the highest fixture connected
to the wasteholding tank. (ASSE
1001-02; device shall not be installed
where the venting of water from the
device during normal functioning will
cause damage.)

[tinstartrvlr]

"From the manufacturer:
Vac/Check cannot be installed in an inaccessible location where venting of water from device during normal operation causes damage. It must be installed in an easily accessible location to end user."

Venting of water? Do they mean when it fails? I thought it should only have air going through it normally. Guess they dropped the ball on mine; its under the sink (easily accessible) and when it decided to malfunction, the floor and everything below it got wet. Think the damage will be evident someday.

[Lynnmor]

From the manufacturer:
Vac/Check cannot be installed in an inaccessible location where venting of water from device during normal operation causes damage. It must be installed in an easily accessible location to
end user.

Instructions

Mine was right next to my silverware and directly above the main electrical inlet, all hidden by the kitchen cabinet.

In order for a back flow problem to happen with the piece of junk removed, the tank would have to be full to the level of the sprayer, the check valve would have to fail, the water would need to be turned on, the campground water system would have to fail, the water pressure would need to drop below zero pressure and any back flow prevention provided in the campground system would need to fail. I weighed that against the fact that I did have contamination in the kitchen and a real electrical hazard. The code police don't sleep in my trailer. :Z

[Bill_Satellite]

Yep, just blow air through it. Where there is no water there is no problem.

[brulaz]

Yikes, my Vacuum Breaker/Check Valve is located in the electrical cabinet.

And I've never winterized it. We go to Florida every winter so I guess I've just been lucky with the relatively mild spring/fall freezes.

How DO you winterize it?
Can't think of any way to pump in anti-freeze, so you must blow it out with compressed air? Hopefully not damaging the valve ...

[dougrainer]

tinstartrvlr wrote:
Bill, I have no water issues except when I hook up the flush hose. Going to find someone to turn on the water while I look at the setup. Everything except the hose going under the floor into the tank is visible, under the bathroom sink. I thought maybe the sprayer was blocked in the tank and causing the fresh water to spray out since it has nowhere to go. Going to use a manual sprayer to clean the tank and see if that helps before I try the hookup again.

Doug, I like the idea of a sturdy brass one. Are they all pretty much the same or do I need to worry about getting the right one? Seems like a pretty basic thing but I hate to assume anything.

1. If the nozzle is clogged NOTHING will happen---no water will flow
2. The Brass/metal ones are all the same for this application.
3. From another post---IF you have removed a sewage filled nozzle, and clean it out, do NOT drill out the holes. WHY would you do that??????? Just makes it easier for sewage to flow in and also STOPS the forceful spray that the holes are designed to shoot out to clean the tank. Doug

PS. I do not believe this system has a plumbing code. It is a COMMON SENSE code to install it and maintain it as designed.

[jrclark]

A few years back the black tank flush failed to work in my motorhome. I took it out and found all the little holes were clogged. Solution either replace the flusher or drill the small holes out. Either way all is well.

[Ralph_Cramden]

Lynnmor wrote:
I simply eliminated the vacuum breaker, no more water drips.

I did the same, before I even used the trailer foir the first time.

Surprisingly you did not alert the plumbing code police with your post........................Yet..... LOL.

[tinstartrvlr]

Bill, I have no water issues except when I hook up the flush hose. Going to find someone to turn on the water while I look at the setup. Everything except the hose going under the floor into the tank is visible, under the bathroom sink. I thought maybe the sprayer was blocked in the tank and causing the fresh water to spray out since it has nowhere to go. Going to use a manual sprayer to clean the tank and see if that helps before I try the hookup again.

Doug, I like the idea of a sturdy brass one. Are they all pretty much the same or do I need to worry about getting the right one? Seems like a pretty basic thing but I hate to assume anything.

[dougrainer]

3oaks wrote:

Lynnmor wrote:
I simply eliminated the vacuum breaker, no more water drips.

Yep, the more the manufacturers add to RVs, even simple things, the more that can become troublesome. If mine gives me any trouble at all, I will do the same.

Our first TT didn't even come with a vacuum breaker in the black tank flush line. It only had a check valve. Our new TT came with a check valve and a vacuum breaker in that line.

1. The aftermarket Black Flush kits have a Check Valve in the water hose inlet, because it is very difficult to install the above floor vacumm breaker/check valve. The aftermarket kits do that to prevent sewer water and SMELL from coming out when the black tank level rises above the spray nozzle.
2. The FACTORY installed system uses that above floor vacumm/check valve usually located under the Lavy sink to keep the odors and the black water from running out when the black water rises above the spray nozzle in the tank. The factory installed systems specifically state that the Inlet does NOT have a check valve. That allows the water in the input water line to drain out when you disconnect the hose.
3. Removing the above floor check valve will then cause odors that will come out at the water bay area where the flush water connection is located. I guess it is also possible, with the check valve removed and the black tank level above the spray nozzle you may get a siphon affect in transit and then have sewer water come out the fill nozzle. I would NOT like to test that theory. Doug

[3oaks]

Lynnmor wrote:
I simply eliminated the vacuum breaker, no more water drips.

Yep, the more the manufacturers add to RVs, even simple things, the more that can become troublesome. If mine gives me any trouble at all, I will do the same.

Our first TT didn't even come with a vacuum breaker in the black tank flush line. It only had a check valve. Our new TT came with a check valve and a vacuum breaker in that line.

[Lynnmor]

I simply eliminated the vacuum breaker, no more water drips.

[neschultz]

They are talking about the air gap/check valve in the line to the actual flush valve. It's often in the bathroom. Mine is under the kitchen sink.

When I looked at the specs on mine when I had to replace it, I noticed that it requires at least 25 psi to seal......so don't turn the water on slowly