Waste vent lesson!

[Chimo]

I’m wondering if I have an obstructed waste vent too. When I pump out all the water in the toilet bowl is sucked out. I would think a normally functioning vent would allow air in preventing the toilet bowl to empty.

Ring the alarm bell here!

If this is happening you run the risk of collapsing your tank. There are several threads here on adding filters, both homemade and professional. We added the Big Orange filter and that has a relief valve included, just in case. Even with that feature I always unscrew the port on the top of the tank when I pump out. Gives me the chance to hose out the tank as well. Whether it’s a plugged line or filter the risk of a tank collapse exists. What you’re describing would indicate low pressure in the tank.

 

[PNWTX]

Been reading through this, and other, posts trying to decipher if it's possible to access the vent screen from outside the boat. Does anyone know? I think ours is at least partially blocked.

Thank you.

 

[cmwahl]

When you are pumping out the tank at a marina pump-out station, place your hand over the vent. You should feel a vacuum sucking your hand against the vent. If you don’t feel this, you may have an obstruction. If the Pumpout material seems puny, this also may indicate a partial obstruction in the vent line.

We recently had a situation where we wondered if the vent was obstructed because we could only pump out a minimal amount before stuff stopped coming out. We thought the initially thought the marina pump was not working, but it checked out fine. We also thought the vent line might be obstructed, but the vent was not obstructed. The cause was the design of the waste tank in the R27 classic. The take off line for the waste tank is actually not at the bottom of the tank. It is at the bottom side of the tank. This means that even with a “complete” Pumpout, there is still about 2 inches of waste that never gets adequately pumped out, even if you meticulously rinse the tank after each Pumpout). Over time the sludge in the bottom of the tank congeals and may eventually plug up the outlet when a glob mobilizes when you try to pump out. Fortunately there is a solution which is to make a suction tube that you can use to thoroughly clean out the bottom of the tank periodically. There is a round 4 inch screw out port on the top of the tank ( of which I was totally unaware of until the helpful marina staff at Friday Harbor pointed it out) that you can unscrew and suction the tank out completely with the suction tube. We fabricated a suction tube by using a 2 foot length of 1 1/4 inch pvc pipe with standard Pumpout adapter at one end. The suction hose from the marina Pumpout connects to the tube and this tube acts as a rigid vacuum nozzle that can suck all that nasty stuff away on the very bottom of the tan.

 

[Jimbo]

My question is, how are solids getting into the vent line in the first place?

I am not familiar with boat plumbing but I am with home plumbing, and I am pretty sure they are designed so as to never be plugged with solid waste (ice in cold climates is another story).

Just seems to me that MAYBE proper maintenance and regular pumpouts are not being done to get to the point where solids are plugging the vent line?

 

[cmwahl]

Yes, it’s proper maintenance, if the tank gets too full, then it will slosh to the top. And then there can be marine growth after the slosh. But there could be other reasons too.

 

[Stevewiens]

As I was reading this I thought the REAL lesson was going to be never to put your lips on or blow into the waste line. Eeeeewwwww. :lol:

Glad you lived. Had the same problem on our 27 and it was pretty disgusting. Fortunately, the waste line and vent are easy access. Not so much on the 29CB.

Jeff

I was at the R27 today installing a waste vent filter. The reason I wanted this is we've had an ongoing issue with waste odors, and this is the obvious solution. However, the odors seemed to be emanating from inside the boat rather than outside, but still I assumed lack of filter was the culprit.

So, I cut the vent line, installed the filter fittings, and screwed in the bottom side of the filter. Before attaching the top side, I decided to blow into it to make sure all was well. Sure enough, completely blocked. Couldn't push even a puff down the line. So I took the filter back off and removed the vent line from the elbow fitting at the tank. Disgusting grey sludge came out of the line, and I saw that the elbow fitting was packed solid. With the line off, it was quite easy to get a piece of wire in there and completely clean out the elbow. I cut a new piece of line, reinstalled everything, and now the vent line is flowing free.

Another thing we noticed previously was that after flushing the head, it would partially back fill water from the waste outlet. Pretty obvious why that was happening now. I'm lucky we didn't cause major damage to the waste tank, as those heads have a pretty powerful flush and I'm guessing that was quite a bit of pressure.

Some of you old salts probably know all about this, and clear out your waste vent regularly, but this was new to me. Now that the filter's installed, checking and clearing the waste line at the tank will be easy peasy by just undoing the lower filter fitting.

Are there step by step instructions to clear the vent? I don’t know how to do that and our toilet is starting to spit back and not fully drain

 

[watson1987]

To clear the vent I use one of the following method with a tiny plunger. I tip it upside down in the water, try to keep it full, and quickly tilt it to seal around the vent and haul. From there I try to pump the water-filled plunger into the vent to push anything stuck back into the tank. Sometimes it takes a few plungers full of water

I keep one on board all the time, I use the same procedure for the kitchen sink, as sometimes the vent/drain gets clogged too, and shifting around the debris lets it flow out.

https://www.amazon.com/Master-Plunger-Designed-Bathroom-Kitchen/dp/B08FVW8T3G?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A1CLJM9X3W55RM