Black tank flush

Kenm78

Member
2023 Gravity 3950.

Trying to flush black tank and it’s like nothing is flowing. What am I missing? I’ve tried changing the valve settings and hose is rock hard and I don’t hear any water flowing….

Black tank valve open and no water coming out.

White hose is not used for food grade by the way it was discolored and I felt cheap and not replace it so I’m using it for black tank flush.
 

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wdk450

Well-known member

JohnDar

Prolifically Gabby Member
If you can access it, replace it with a brass one.


Sent from my iPhone using Tapatalk
 

sengli

Well-known member
Do you hear any water flowing in behind the UDC area? Like others have said the back flow prevention valve might have been installed backwards, and accordingly will not allow any water to flow. There are a lot threads on this ASV valve on this site. Its a common issue for a lot of reasons. Many people, including myself have had the issue that when used the valve sticks open, allowing water to gush into the interior of the basement of the coach. Causing damaged components.
 

Roller4tan

Well-known member
Another issue may be the sprays are plugged by TP and other semisolids in the tank. Whatever it is, dries out and gets hard.
One time I added another back flow preventer to the outside shower and ran the hot water into the tank flush port. Took a while but it finally broke through.
 

jimcat

Well-known member
So, yo u have nothing coming out of your black tank?.I would try dumping about 3 gallons of water down the toliet.. have some one outside to see if anything comes out then.. if not there is a clog
 

Gary521

Well-known member
This atmospheric check valve is totally unnecessary. To remedy the situation, just bypass the valve completely and this will fix the problem for good. My check valve did not work from day one and I did this. From the basement, you can see the pipes going into the wall and coming back down and going to the black tank. Just bypass the pipes going up and down. Poof! problem solved. Put a check valve on the back side of the water inlet for the flush.
 

LBR

Well-known member
This atmospheric check valve is totally unnecessary. To remedy the situation, just bypass the valve completely and this will fix the problem for good. My check valve did not work from day one and I did this. From the basement, you can see the pipes going into the wall and coming back down and going to the black tank. Just bypass the pipes going up and down. Poof! problem solved. Put a check valve on the back side of the water inlet for the flush.
Replacing with a check valve is definitely something an owner can do... unfortunately the manufacturers are bound to the requirement of using an air-gap device. On an off-day, if the device is installed backwards, es no bueno for sure.
 

wdk450

Well-known member
Replacing with a check valve is definitely something an owner can do... unfortunately the manufacturers are bound to the requirement of using an air-gap device. On an off-day, if the device is installed backwards, es no bueno for sure.
Especially with NO comprehensive testing of the plumbing (and other) systems immediately post manufacture.
 

ScottM126

Member
2023 Gravity 3950.

Trying to flush black tank and it’s like nothing is flowing. What am I missing? I’ve tried changing the valve settings and hose is rock hard and I don’t hear any water flowing….

Black tank valve open and no water coming out.

White hose is not used for food grade by the way it was discolored and I felt cheap and not replace it so I’m using it for black tank flush.
Hi,

I had this problem with my new camper and brought it back to dealer to find out when they put it together the flush hose was kinked. They fixed it and now it works fine. Hope this helps
 
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