Will a jabsco macerator lift?

[Gripfast]

I have a lake sailing boat where pump out is problematic. Boat has a head and holding tank. I installed a jabsco maserator and a length of discharge line with a ball valve. The plan is to pump the holding tank to a portable RV holding tank at the end of the weekend and dump it at a RV dump station along the way home.
Problem is either the pump wont lift the black water the 2.5 feet to get it out of the boat, or i have a suction line problem....blockage or suction leak.

Its an old tank and hasn't been used in a couple years.
Am i looking in the right area or am i not?
Pump runs, nothing comes out.

[Dockhead]

Typical behavior of these pumps. They can be very hard to prime. Mine does this too, and not even uphill. Maybe someone can suggest something to do about it.

It is rated to self-prime up to 1.2 meters, but in practice -- it's a race between burning up the impeller and actually getting the flow going. My solution is to carry multiple spare impellers -- maybe someone has some other suggestion.

[sailorboy1]

Try adding some water into the pump discharge line and see it will prime then. Plus that will prevent the impeller running dry while it primes.

[peghall]

A macerator pump should have no trouble lifting tank contents up to at least 4 ft. If the toilet/tank/macerator haven't been used in several years, the problem could be a blocked tank vent. Dirt daubers love to build nests in vent thru-hulls...or the blockage is also likely to be at the other end of the vent line--the vent fitting on the tank and that end of the hose...vent blockages rarely occur anywhere else in the vent line. A blocked vent would cause the macerator--and would also cause any pumpout--to pull a vacuum that won't let the it pull anything out or even prime. If you've tried a lot and/or let the macerator run dry, you've prob'ly fried the impeller in it by now.

So the first step would be to clear the vent...then try it, and if it still won't work, replace the impeller in the macerator pump. If it STILL won't work, there may be a blockage in the tank discharge line, most likely at the discharge fitting.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

[Gripfast]

It ran till the run dry feature shut it down, twice....so i will replace the impeller. I can lift and tilt the tank to fill the line, but before i do that, i will try to clear any vents. It has a threaded lid, i can open the lid to make sure it vents.
This has the potential to be a mess....
Thanks.

[peghall]

It ran till the run dry feature shut it down, twice

The MOTOR ran (the run dry feature only protects it from burning out and/or catching fire) , but that doesn't mean the impeller was still able to move anything. Running dry will "fry" an impeller.

You'll have to clear the vent to be able to use the toilet...'cuz flushing against a blocked vent will pressurize the system, which has a LOT more portential to make a mess than just opening an inspection port (just opening the pumpout fitting cap won't provide the source of air needed for the macerator to remove anything, but it will relieve any pressure in the tank). So you might as well bite the bullet and clear the vent. It's not hard to do. Use a screwdriver blade or whatever works to scrape out the vent thru-hull...then pull the vent line off the tank (warming it a bit with blow dryer will make it easier) and scrape out the vent fitting on the tank and that end of the vent line. Then replace the impeller in the macerator before you try to use it again.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

[Carver Power]

Make sure your holding tank is not blocked from outlet, "Sludge" on bottom of tank.

[Gripfast]

Yep, going to take a closet auger and see if its plugged, that is a very likely thing. The tank sat for a couple years after i bought the used boat before i installed the mascerator a couple weeks ago.
Its been a renovation project for a while. I should have looked at the tank closer.
I bet the po left crap in there and it could have solidified around the discharge fitting.

[jtsailjt]

I have had more trouble with these pumps than almost anything else on the boat and as a result have removed it, after replacing it twice, in favor of a Whale Gulper pump which doesn't have impellers that could burn out. The problems I had with macerator pumps were many:

If not used for a week or so, they would tend to seize up so when turned on the amperage would spike and trip the CB so I'd have to stick a screwdriver in the end to turn the impeller to "unseize" it so the motor would turn. Sometimes, before the CB tripped, the wires near the pump would feel warm to the touch which probably meant I needed a lower amp CB (I realize that was my fault, not the pumps). Since the CB was not within reach of where the pump was located and if the impeller needed help to get started it would trip the CB within seconds, it became a 2 person operation, one person to operate the CB and the other to help assist the pump to get it turning.

They are not good at lifting and I was always afraid that if I ran it dry in an attempt to pull the waste up from the holding tank, I might burn out the impeller.

They are very noisy.

I had to replace the long thin bolts that hold it together because they corroded after just 2 years.



So, I inserted a Whale Gulper toilet pump where my macerator pump used to be and have had no problems with it at all. It takes a bit longer to empty the tank but the amperage draw is consistent with no spikes and is lower than the macerator drew. It's also so quiet that I have to listen carefully to detect that it's turned on, but if I forget it and leave it on for awhile, that's OK because they can run dry all day without harming them. I'll never go back to using a macerator pump to empty my holding tank.

[CHRISBENJES]

It must be blockage from tank. A blocked vent will not stop macerator from dumping the tank. Air will instead be sucked into the tank through the toilet. I intentionally block my vent and then run the tank macerator to empty toilet and toilet discharge line for maintenance. Do check the vents anyway, you definitely need them to flush.

[peghall]

Air will instead be sucked into the tank through the toilet...

Not always...it depends on the length and routing of the toilet discharge hose among other things. But even if it works, it's a very bad idea because marine toilet pumps are not designed to have air sucked through 'em (yes, I know the air is being sucked through the bowl, but whatever goes out of the bowl has to go through the bottom part of the pump). It won't work at all unless the joker valve in the toilet discharge fitting is so worn out that the slit has become an open hole, making it useless for the functions it's designed to do. The suction would just pull the "lips" on a joker valve in decent shape closed more tightly.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

[CHRISBENJES]

Sorry, but it works just fine with a good joker valve, even a brand new one. Vacuum easily pulls it open. Joker valve lips are designed to close when there is pressure from the back side, not vacuum. Joker valve is always checked when toilet maintenance is performed.

[Dockhead]

Originally Posted by peghall

.. . It won't work at all unless the joker valve in the toilet discharge fitting is so worn out that the slit has become an open hole, making it useless for the functions it's designed to do. The suction would just pull the "lips" on a joker valve in decent shape closed more tightly.. .

Are you sure about that? Seems to me like the water will be pulled the right way through the joker valve.

Don't know about the pump, though, so I certainly wouldn't do this.

[peghall]

Are you sure about that? Seems to me like the water will be pulled the right way through the joker valve.

Oops...my brain seems to have made a left turn...you're correct. The suction would pull the lips closed. But that would only make it harder to pull enough air from the toilet bowl through it.

However, it would have to be AIR, not water, being pulled through. If the suction is pulling water through, that would be bad, 'cuz most marine toilet bowls don't hold water. Any more than the <cupful of water left in the bottom of the bowl being pulled through would either be waste left in the toilet discharge line due to incomplete flushing or would have to be being pulled through the pump from the thru-hull.

My brain burp or yours notwithstanding, there are a lot of reasons why relying on the toilet to supply air to the tank is still a bad idea.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

[Mike Banks]

Macerators aree not designed to lift--because of the blades designed to chop up the solids within the stream. They push very well though--so set your macerator right next to the heads pedestal and you should be OK pumping it to any reasonable height--but you will need a syphon-breaker as well, to stop the macerated waste within the ascending part of the pipe (or the excess flush water) running back and overflowing the pedestal.