Back pressure in sanitation line

[Windflyer]

Hi,
I replaced my sanitation line recently (2009 Hunter 36). It was pretty straightforward. I have a jabsco electric toilet. It has a one inch very flexible line that exits the head. It is about 10 inches long. It connects to the standard white 1.5 inch sanitation line using a "reducer" plastic fitting, which then connects to the holding tank.

I made all the connections and clamped them tight. It was a "one for one" swap - as in I simply replaced the line exactly as it was before. Now when I do test flushes, I hear air leaking out of the connection between the two hoses, and small amounts of water drip out. If I undo that connection, I get a lot of water flow back up the hose. I have clamped very tight, but have not used any sealant, glue or similar.

When I remove the connection at the holding tank and flush, some water is pushed out of the end of the hose, and it is brand new, so obviously it isn't block. The toilet does empty properly and I am not getting backflow into the head. I have tried leaving the pump out cap off and also cleaning the vent, so I don't believe there is a vacuum being created in the holding tank.

However, I can't seal the connection, and it concerns me that there is so much pressure in my line. Is this normal? Is it just the weight of water in the line that is causing this back pressure?

Any help appreciated.

 

[Peggie Hall HeadMistress]

I see you've just joined sbo.com today...welcome aboard!

First, I would have replaced the 1" toilet discharge fitting with one that can use either 1" or 1.5" hose...eliminating the need for a reducer. And btw, all hose connections should be double clamped, with screws 180 degrees apart, or at least 90 degrees if access makes 180 impossible

As for your pressure problem...I suspect that a blocked tank vent is the culprit. The back pressure is escaping out your leaking fitting instead of going all the way to the bowl. You said you've cleaned it, but....maybe not.

The two most common locations for a vent blockage are the vent thru-hull and the other end of the vent line--that end of the hose and the vent fitting on the tank. Start by cleaning out the thru-hull...use a screwdriver blade, ice pick--whatever works. If that doesn't result in a spew out the vent, you'll need to relieve the pressure before removing the vent line from the tank to clean them out...so open the deck pumpout fitting VERY CAREFULLY with a hose at the ready. Be sure you're UPwind of it! Scrape out that end of the vent line and the vent fitting on the tank...reconnect the vent line.

If you want to prevent future vent blockages, replace the "vent" thru-hull (designed to keep sea water out of water and fuel tanks, but boat builders use 'em on holding tanks too) with an open bulkhead, aka "mushroom" thru-hull. This will allow you to put a hose nozzle against it to back flush the vent line every time you wash the boat and/or pump out...anything that's tried to set up housekeeping in the vent line will just get a water slide ride into the tank.

--Peggie

 

[Windflyer]

I see you've just joined sbo.com today...welcome aboard!

First, I would have replaced the 1" toilet discharge fitting with one that can use either 1" or 1.5" hose...eliminating the need for a reducer. And btw, all hose connections should be double clamped, with screws 180 degrees apart, or at least 90 degrees if access makes 180 impossible

As for your pressure problem...I suspect that a blocked tank vent is the culprit. The back pressure is escaping out your leaking fitting instead of going all the way to the bowl. You said you've cleaned it, but....maybe not.

The two most common locations for a vent blockage are the vent thru-hull and the other end of the vent line--that end of the hose and the vent fitting on the tank. Start by cleaning out the thru-hull...use a screwdriver blade, ice pick--whatever works. If that doesn't result in a spew out the vent, you'll need to relieve the pressure before removing the vent line from the tank to clean them out...so open the deck pumpout fitting VERY CAREFULLY with a hose at the ready. Be sure you're UPwind of it! Scrape out that end of the vent line and the vent fitting on the tank...reconnect the vent line.

If you want to prevent future vent blockages, replace the "vent" thru-hull (designed to keep sea water out of water and fuel tanks, but boat builders use 'em on holding tanks too) with an open bulkhead, aka "mushroom" thru-hull. This will allow you to put a hose nozzle against it to back flush the vent line every time you wash the boat and/or pump out...anything that's tried to set up housekeeping in the vent line will just get a water slide ride into the tank.

--Peggie

Hi,
thank you for the welcome - long time lurker, first time poster....

Good point on the one inch hose, I was thinking same and will do so at a later date. Given how inflexible the "white hose" is, I suspect I will still need a flex hose and then a same size coupler to the white hose?

All is double clamped and pretty tight.

Regarding the pressure, if the vent is blocked but I can't find the blockage (I can't seem to find one), could I trouble shoot the problem by leaving the pump out cap off and test flushing? I think that should relieve any pressure, but maybe not? My tank is empty right now.

Will there always be sitting liquid in the sanitation hose? Or is a flush meant to push all liquid into the holding tank?

Thanks!

 

[Peggie Hall HeadMistress]

Good point on the one inch hose, I was thinking same and will do so at a later date. Given how inflexible the "white hose" is, I suspect I will still need a flex hose and then a same size coupler to the white hose?

Maybe...What brand/version hose did you buy?

if the vent is blocked but I can't find the blockage (I can't seem to find one), could I trouble shoot the problem by leaving the pump out cap off and test flushing?

Nope... all that would do is pull air in and provide an escape for air through the pumpout fitting, and that's possible only because your tank is empty. Did you try to find the blockage by following the directions in my previous post?

Will there always be sitting liquid in the sanitation hose? Or is a flush meant to push all liquid into the holding tank?

That depends on how long the toilet discharge line is and the routing...whether it's an uphill run and/or has to go up and over, around and through, or fairly short (+/- about 6') or longer. There are workarounds and I'll be glad to help you sort out what you need to do to get flushes to the tank.

Now when I do test flushes, I hear air leaking out of the connection between the two hoses, and small amounts of water drip out.

Hopefully you used a male-male "hose mender"...if so, wrapping both ends with plenty of Teflon tape should solve that problem.

--Peggie

 

[Windflyer]

Maybe...What brand/version hose did you buy?

IT"S WHITE SMOOTH 1.5inch PVC ANTI ODOUR SANITATION HOSE. 148 series? I THINK IT IS GENERIC BRAND.

Nope... all that would do is pull air in and provide an escape for air through the pumpout fitting, and that's possible only because your tank is empty. Did you try to find the blockage by following the directions in my previous post?

I DON"T THINK THERE IS A BLOCKAGE, BUT JUST TO BE SURE I FLUSHED THE HEAD A FEW TIMES WITH THE PUMPOUT CAP OFF. SOME WATER FLOWED INTO THE HOLDING TANK, BUT THE BACK PRESSURE IN THE HOSE SEEMED TO CONTINUE.

That depends on how long the toilet discharge line is and the routing...whether it's an uphill run and/or has to go up and over, around and through, or fairly short (+/- about 6') or longer. There are workarounds and I'll be glad to help you sort out what you need to do to get flushes to the tank.

I REPLACED THE FACTORY INSTALL IN THE SAME WAY IT WAS INITIALLY INSTALLED. THE TOTAL RUN IS ABOUT 15 FEET. TWO ALMOST 90degree BENDS (WHICH I HAVE SMOOTHED OUT A BIT) AND SOME "UPHILL" SECTIONS.

Hopefully you used a male-male "hose mender"...if so, wrapping both ends with plenty of Teflon tape should solve that problem.
I HAVE A MALE MALE BARBED CONNECTOR. I WILL TRY THE TAPE.
--Peggie

Thanks very much for the input.

 

[Peggie Hall HeadMistress]

What brand/version hose did you buy?
IT"S WHITE SMOOTH 1.5inch PVC ANTI ODOUR SANITATION HOSE. 148 series?

I was afraid you'd bought one of the more expensive odor permeation resistant hoses. Flexible PVC #148 is the cheapest hose, which unfortunately is likely to permeate with odor rather quickly...how quickly is unpredictable. It was on one of my own boats for 7 years without a trace of odor...permeated within 90 days on the next boat. Typically it happens within a year or two. That's the bad news. The good news is, when you do have to replace it with hose that actually is odor permeation resistant, you'll be able to run 1.5" all the way from the toilet to the tank and we can plot a routing plan that will get your flushes to the tank with a minimum amount of pumping and flush water. Meanwhile, I'd leave everything as it is.

--Peggie