Long question, bottom line about holding tank vent.

[Zeus2012]

We liveaboard a 2012 Beneteau Sense 43. We very recently replaced the head hose and the two joker valves in the hose between the head and the tank. We have two jokers because some of the Senses had a second joker valve plumbed into the line closer to the tank. The head now flushes like it's jet propelled. You should have seen the old valves!
Our head now FREQUENTLY backflows back into the bowl. The tank is empty, the tank is full, makes no difference. Does anyone know if Beneteau includes a filter in the vent line to the tank? The reason I ask on the forum is our boat was built in France, not the US. I have no idea what kind of documention US Beneteau provides, but ours is worthless. Worse than worthless. As is our dealer, because I had to turn them in to Beneteau corporate to get them to pay me for a warranty repair.
ANYWAY, I have no one local to ask without paying $130/hour. I bought an inspection camera, but cannot get it past the 90 degree elbow in the vent line. I have blasted water into the vent line from outside the boat and can hear it going into the tank. I just do not want to take the line apart again if the problem is something else.

 

[JamesG161]

Our head now FREQUENTLY backflows back into the bowl

What is the brand name of your head and is it a manual pump type?

If you know the Hold Tank vent line is open, then it should not be the back flow problem.

What is the back flow, Water or Sewage?
Jim...

 

[Peggie Hall HeadMistress]

There's only two things that create backflow: something downstream of the toilet--a blocked vent, a clog or other obstruction in the plumbing that's creating back pressure--or bowl contents/water left in a toilet discharge line that runs uphill doing what water does: run back downhill.

First thing I'd do is get rid of the second joker valve...or maybe both, if the first one is also downstream of the toilet. The system only needs one joker valve--the one that's in the discharge fitting on the toilet. I've never heard of anyone putting any extra ones in the discharge line. It's a blockage in the line that only demonstrates how little boat builders understand sanitation systems or how to install one...and European builders and yards are even worse than those here...I've even heard of tank vent lines terminating inside cockpit settees!
Did your backflow start immediately after you replaced the hoses and joker valves? If not, how long ago did you replace 'em...and when did the backflow start.
Is it just seeping slowly into the bowl, or flowing back into the bowl?
Is your toilet manual or electric? Make/model/age?
I strongly suspect that the extra joker valve(s) are the source of your problem...but I'm not convinced that your vent is totally open...you forced water through the thru-hull, but and heard it go into the tank, but how much actually made it to the tank? The two most common locations for a vent blockage are the thru-hull and the other end of the vent line--that end of the hose and the vent fitting on the tank. Use a screwdriver, ice pick or whatever works to scrape out any buildup in the thru-hull. I don't think there's a filter in the vent line (you've owned--lived aboard--the boat for 4 years and don't know every inch of it yet???). If there is, filters only last a year and are "toast" immediately if they get wet...the charcoal swells up and creates a blockage...so if there is one and it wasn't blocked before you put water down the vent line, it is now.
I'm pretty sure that you and I are gonna have to spend some time on the phone--'cuz there's a limit to the amount of typing I'm willing to do--sorting out all that's right, wrong and "seriously???" with your sanitation system...so send me a PM and we'll find a mutually agreeable day/time when we can spend up to an hour together.

 

[Zeus2012]

Head is Jabsco Quiet Flush electric with a macerator. Flushing action is incredibly fast now that we replaced the hose. Backflow is sewage, really just 'used' water. We do not put toilet paper down our head. The head will be one year old in October. It was replaced by our boatyard when the head stopped flushing, which turned out to be a jammed macerator from crystalized granular head chemicals that were provided by our pumpout company. I made the discovery, not the boatyard. The pumpout guys have since discontinued use of the chemical because they had complaints from others on the same issue after I proved what happened.

We replaced the hose about a month ago when it again stopped flushing, which turned out to be calcium deposits plugging the hose.

When we bought our boat we were given zero orientation. One of the reasons I will no longer have anything to do with the dealer. This is our first boat, we always chartered before. We have lived on the boat for 11 months. My husband works full time and I have had a torn shoulder since last October, plus three surgeries. The shoulder is not yet fully functional and I cannot get into the nooks and crannies and do anything with my hands until it is. I am not allowed to lift anything.

The boat has always had a backflow issue. When it was new it happened maybe once every couple of months. The backflow is gradual, but sometimes I can stand and watch it bubble up and it will take 5 minutes or more to fill. Since we had no orientation on the systems, and only used it occasionally for the first three years, we did not even know about the valves. We found out about the second valve when we replaced the hose. Jabsco knew nothing about it, the parts person in South Carolina, Debbie, told us about the second valve and that it was put in at the factory on SOME boats of our model because there were backflow issues when heeling in rough conditions at sea. The first valve is part of the head. The hose is 1". The second valve is larger and is at the beginning of a 1.5" section of hose that actually attaches to the tank.

 

[JamesG161]

The backflow is gradual, but sometimes I can stand and watch it bubble up and it will take 5 minutes or more to fill (seepage).

Is the boat at berth and static when this occurs?

First guess...
Your head discharge line may not have a "high loop" which normally is the first stop of back flow due to boat heeling.
Joker valves are a poor excuse for a liquid back flow preventer, but they are common practice. So Joker valve "seepage" of liquid is easy, solids... no so much.
Jim...

 

[Zeus2012]

The boat is in the berth when it backflows. It has a high loop.

 

[JamesG161]

Hmmm bad guess on my part.

If you are sure your Hold Tank Vent is open, then it is the water in the uphill part of the High loop, seeping back through the Jokers.
I am assuming this back flow occurs no matter the level in you Hold tank ( no siphoning back)

If you can get your discharge hose diameter and rough length of the hose to the top of high point, we can approximate the volume of water back flow possible ( without a siphon). This may confirm where the water is coming from.
Jim...

 

[Peggie Hall HeadMistress]

From what you've said, I'm reasonably certain that rerouting the toilet discharge line and removing the second joker valve, which has already proved that it does little if anything to prevent backflow, but is creating an obstruction in the discharge line will solve your problem. And I'll be glad to help you do that.

If you can get your discharge hose diameter and rough length of the hose to the top of high point, we can approximate the volume of water back flow possible ( without a siphon). This may confirm where the water is coming from.

We already know that the discharge hose is 1". There's no siphon...siphons are started by water being PULLED through a hose...the toilet pushes it. And the volume of water in the discharge hose depends more on how long the user leaves his/her finger on the flush button than the length of the hose.

 

[Zeus2012]

Thanks everyone. Appears we have work to do. Now to find the time! I will post later on the success or failure of the project

 

[Zeus2012]

The vent has no filter or obstruction. We took the hose from the toilet to the tank off again and discovered that our "new" macerator joker valve was defective! Surprise, surprise. We inspected it carefully when we installed it two months previously, it looked like it should, no daylight visible, but the backwash issue started immediately. We replaced the defective valve and it has almost completely eliminated the backwash issue. Thanks everyone. We'll see how long this

one lasts.