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Effluent Discharge from Holding Tank Vent

LVGS

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Apr 8, 2018
32
Hunter 33 Nanoose Bay, Vancouver Island
While several kilometres off-shore, I opened the discharge thru-hull and ran the macerator in our '06 H33. After a relatively short period, my wife yelled from the cockpit that there was effluent 'shooting out in sputters' from the holding tank vent.

What might have caused this? I would have assumed that opening the thru-hull and running the macerator would have relieved the tank of pressure, even if full and that the vent is solely intended to release gases. Any thoughts would be greatly appreciated.

Thanks, as always.
 

LVGS

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Apr 8, 2018
32
Hunter 33 Nanoose Bay, Vancouver Island
If the discharge hose was blocked or the thruhull was closed, the back pressure could do that. No other causes.
Thanks very much Don. The thru-hull was definitely open. When replacing the macerator earlier this year every indication was that flow from the tank to the macerator and then to the thru-hull was unimpeded.

Any practical advice on how to check for a blockage?

Thanks again.
 
Apr 5, 2009
1,565
Catalina '88 C30 tr/bs Oak Harbor, WA
A DC motor will turn the wrong way if you have the polarity reversed. I would make sure that you have + to the red wire and - to the black wire. If it is backards, you will fill the tank rather than empty it. :what:
 
Dec 2, 1997
8,092
- - LIttle Rock
Is there any possibility you could have installed the new macerator pump backwards? If so, it would pull sea water in instead of pulling tank contents out, overfilling the tank and pushing the overflow out the vent.

--Peggie
 
  • Like
Likes: NYSail

LVGS

.
Apr 8, 2018
32
Hunter 33 Nanoose Bay, Vancouver Island
A DC motor will turn the wrong way if you have the polarity reversed. I would make sure that you have + to the red wire and - to the black wire. If it is backards, you will fill the tank rather than empty it. :what:
That’s a good point Hayden, I will definitely check.
 

LVGS

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Apr 8, 2018
32
Hunter 33 Nanoose Bay, Vancouver Island
Is there any possibility you could have installed the new macerator pump backwards? If so, it would pull sea water in instead of pulling tank contents out, overfilling the tank and pushing the overflow out the vent.

--Peggie
Thank you Peggie, I do not believe that is the case but will confirm when I go down to the boat later today and post a pic of the installation.
 
Dec 2, 1997
8,092
- - LIttle Rock
Brainstorming a bit... Unless the tank was full-to-overflowing out the vent before you turned on the macerator pump, I'm convinced that turning it on somehow managed to add water to the tank. There's no way that a blockage in the line could do that, so we can eliminate a blockage.

There are only two sources of water to the tank : the toilet and the macerator pump. A wiring error when you installed the toilet could cause it to flush continously when you run the macerator pump (possible, but highly unlikely)... installing the macerator pump backward could cause it to pull in water. So once you eliminate both of those, the only thing left would have to be reversed polarity causing the pump to run backwards.

That is, unless one of you can think of another way to make the macerator pump pull in water.

--Peggie
 
Mar 6, 2008
681
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
Peggy, If you mean placing the hoses in wrong connectors, it will not be possible since the input is 1 1/2" and the output is 1". That leaves us reversed polarity which is easily fixed.
 

LVGS

.
Apr 8, 2018
32
Hunter 33 Nanoose Bay, Vancouver Island
Brainstorming a bit... Unless the tank was full-to-overflowing out the vent before you turned on the macerator pump, I'm convinced that turning it on somehow managed to add water to the tank. There's no way that a blockage in the line could do that, so we can eliminate a blockage.

There are only two sources of water to the tank : the toilet and the macerator pump. A wiring error when you installed the toilet could cause it to flush continously when you run the macerator pump (possible, but highly unlikely)... installing the macerator pump backward could cause it to pull in water. So once you eliminate both of those, the only thing left would have to be reversed polarity causing the pump to run backwards.

That is, unless one of you can think of another way to make the macerator pump pull in water.

--Peggie
Thanks Peggie,

I can confirm the following based on my visit to the boat earlier today (pls see attached pic):
1. Tank is no greater than half full;
2. Macerator pump is installed correctly; and
3. Macerator pump wiring is correct.

This being the case, if there is a partial blockage between the macerator and thru-hull, is there any possibility that is is contributing to a vacuum in the tank that is forcing effluent through the vent when the macerator is turned on? Any other ideas?
IMG_7154.JPG
 
Oct 2, 2008
3,553
Pearson/ 530 Strafford, NH
If the tank is half full, how would anything come out the vent hose? Hmmmmm.
 
Oct 26, 2010
1,405
Hunter 40.5 Beaufort, SC
[QUOTE="LVGS, post: 1711825, member: 141083"

I can confirm the following based on my visit to the boat earlier today (pls see attached pic):
1. Tank is no greater than half full;
2. Macerator pump is installed correctly; and
3. Macerator pump wiring is correct.
[/QUOTE]

@LVGS
Just thinking out of the box here
1. How do you know that the tank is no greater than half full? - Are you are relying on a tank level indicator that may be unreliable?
2. Macerator is installed correctly - that looks right
3. Macerator pump wiring is correct? While your red may be hooked to the red and black to the black did you actually probe with a voltmeter to check that the red supply wire from the dc system is actually positive?

A couple other things to check
4. Is the white in line valve really open? - Yes the handle says its open but did the ball really move to open?
5. At your thru-hull, are you sure the ball is actually moved to the open position or are you relying only on the handle says its open - THIS HAPPENED TO ME - (not yelling, just for emphasis) the valve shaft didn't actually turn the ball so I thought it was open when in reality it was closed (I had to replace the thru-hull)
6. Is it even remotely possible that the macerator pump is internally wired backward? Stranger things have happened. Is this the first time that you have used the macerator since you installed it?
 
  • Helpful
Likes: JamesG161
Dec 2, 1997
8,092
- - LIttle Rock
Peggy, If you mean placing the hoses in wrong connectors, it will not be possible since the input is 1 1/2" and the output is 1".
That's because the standard holding tank fittings are 1. 5" and so are many discharge thru-hulls, requiring a 1.5 x 1" reducing adapter for a macerator pump. Because the discharge on most Jabsco toilets is also 1", the male hose fitting on some tanks can be a 1.5" x 1" reducing adapter...or a replacement custom tank can be ordered with a 1" inlet.

For decades, Jabscos were the only toilets that had 1" discharge fittings Today, almost all toilet mfrs supply a discharge fitting that can be used with either 1" or 1.5" discharge line.

So while it's unlikely to make that mistake , it's not impossible to install a macerator pump backwards...and btw, macerator pumps are the only overboard discharge pumps that do have 1" outlets...manual and electric diaphragm pumps are 1.5" in AND out.

--Peggie
 
Last edited:

LVGS

.
Apr 8, 2018
32
Hunter 33 Nanoose Bay, Vancouver Island
[QUOTE="LVGS, post: 1711825, member: 141083"

I can confirm the following based on my visit to the boat earlier today (pls see attached pic):
1. Tank is no greater than half full;
2. Macerator pump is installed correctly; and
3. Macerator pump wiring is correct.
@LVGS
Just thinking out of the box here
1. How do you know that the tank is no greater than half full? - Are you are relying on a tank level indicator that may be unreliable?
2. Macerator is installed correctly - that looks right
3. Macerator pump wiring is correct? While your red may be hooked to the red and black to the black did you actually probe with a voltmeter to check that the red supply wire from the dc system is actually positive?

A couple other things to check
4. Is the white in line valve really open? - Yes the handle says its open but did the ball really move to open?
5. At your thru-hull, are you sure the ball is actually moved to the open position or are you relying only on the handle says its open - THIS HAPPENED TO ME - (not yelling, just for emphasis) the valve shaft didn't actually turn the ball so I thought it was open when in reality it was closed (I had to replace the thru-hull)
6. Is it even remotely possible that the macerator pump is internally wired backward? Stranger things have happened. Is this the first time that you have used the macerator since you installed it?
[/QUOTE]

Thank you for helping sort through the various contributors to the problem Smokey.

To answer your questions:
1. It is possible to see how full the tank is i.e. unless it is completely full or empty, using a flash light. Unfortunately, the tank level indicator is quite unreliable.
3. Every indication is that the wiring is OEM and therefore, I have assumed as I connected red to red and black to black, this is not the issue. However, I will check with a multimeter has you suggest.
4. The in-valve is definitely open, it was one of the first things I checked.
5. All the thru-hull valves were checked when the boat was lifted earlier this year.
6. It is certainly possible that the macerator itself is incorrectly wired internally. Other than testing it during installation, this is the first time we have used it to any extent. I have a spare (older generation) pump I might try.

Thanks again Smokey.
 
Oct 26, 2010
1,405
Hunter 40.5 Beaufort, SC
@LVGS How hard is it to turn the overboard discharge thru-hull valve handle? When mine failed it was very easy to turn the handle because the shaft had sheared and the handle was not really rotating the ball itself.

After you check the voltage for the input from the boats dc panel:

Can you go over the side, find the correct thru-hull opening underwater and with the valve open, attempt to put something up the hole to make sure it is actually open?

Probably not likely that the pump is internally wired wrong but outside of the box thinking only. If you are going to think about replacing the pump, it might be messy, but prudent, to check the current pump by disconnecting the input and output hose, putting a hose from the tank side in a bucket of water and bumping the macerator motor into a large bucket to see if its actually pumping in the right direction. This is a two person job so you only bump the motor very briefly. Otherwise its a reall mess:poop:

I still don't see how a blocked outlet would pressurize the tank and cause effluent to come out of the vent since the pump should just operate at shut off head and pressurize the line from the macerator output to the thru-hull.
 
  • Like
Likes: JamesG161
Dec 2, 1997
8,092
- - LIttle Rock
This being the case, if there is a partial blockage between the macerator and thru-hull, is there any possibility that is is contributing to a vacuum in the tank that is forcing effluent through the vent when the macerator is turned on?
I can't see how a vacuum in the tank could cause the contents of a half full tank to rise high enough enough to force 'em out the vent...UNLESS the boat is heeled enough to spill contents into the vent line, which often happens when the boat is underway on that tack without requiring a vacuum, but it doesn't seem likely you'd be heeled that much while dumping the tank.

Smokey73 may have hit on the answer: If this is the first time you've used that macerator since you installed it, it's indeed possible that the motor could have been installed backward or internally wired backward, especially if it's a Jabsco.

Most of you are aware that ITT spun Jabsco off to a company called Xylem Flow Control about 10 years ago. What you may not know is that while Xylem is a US company, they do -0- manufacturing in the US...it's all done in 3 locations: the UK, China and Mexico...and Mexico is where everything Jabsco makes that's sold in the US is made, using materials and components sourced from China and other Asian countries. As a result, the quality of Jabsco equipment (which never has been TOP rated, but decent) has deteriorated significantly.

So I'd try another macerator pump (if you have to buy one instead of borrowing one, go with a Johnson Pump this time...pretty much identical to the Jabsco, but much higher quality for close the to same price). Hopefully you can still return this one for an exchange.

Afterthought: Have you tried pumping out instead of dumping? That would be quickest way to determine whether there are any blockages in the discharge line.

--Peggie
 
Feb 14, 2014
5,628
Hunter 430 Waveland, MS
that the vent is solely intended to release gases
Actually the vent is to let Air INTO the hold tank. Air flow rate in = Waste flow rate out.

The only way possible to spurt out of vent, is the reverse pumping per @smokey73 .

The wires have to be reversed at the Breaker switch in your DC panel.

No need to verify with wires at the macerator.
Jim...
 
Dec 2, 1997
8,092
- - LIttle Rock
Actually the vent is to let Air INTO the hold tank. Air flow rate in = Waste flow rate out.
Close, but no cigar. All tank vents--water, waste and fuel tanks-- have TWO functions: to provide an escape for air in the tank displaced by incoming contents--preventing the tank from becoming pressurized... AND to provide a source of air to replace tank contents as they're pulled out, without which a pump, whether it be a pumpout, macerator, water pump or fuel pump, will pull a vacuum that prevents it from pulling anything more out once the limited amount of air in the tank has been used up.

--Peggie