macerator doesn't have enough oumph

[sabbatical88]

Aloha good sailors,
In my 2003 hunter 456, I am finding that the macerator for the fowrard holding tank does not seem to have enough power to pull the waste out. The picture shows my setup. I acutally built a mock setup out of PVC at home that matches the length of the tubing to the deck plate and the height of the macerator above the 'holding tank' to make sure the new macerator had enough oomph, and no problem. The macerator sits up pretty high above the tank (about 18-24") and the hose to the deck fitting is a good 6', so it seems like some serious suction is required. The vents are clear (I can pump out ok from the deck fitting). Since there is no stink, doesn't this mean the hoses are not permiated? What's up? Is this simply a design flaw and I need to lower the macerator? Or do I need to replace all the hoses even though there is no stink? Lowering the macerator is the perferred nixt step since it would be way easier than replacing the hoses. Maybe I can 'prime' the thing by putting a shopvac on the deck plate or maybe put some water into the deck fitting, but I'm looking for a perminent solution.
Thanks in advance for any advice.
-john

 

[jssailem]

Generally there is a Y valve not a T fitting where the circle is. This directs the suction to the holding tank through the Y valve to the pump. A T fitting lets you suck air down the deck outlet as well as the effluent from the tank. That may be why the pump is having problems.

 

[Ralph Johnstone]

Air ingress will destroy the vacuum that the macerator is trying to develop.

 

[dlochner]

Check the electrical connections and the voltage at the pump when it is running.

 

[RoyS]

Be sure to pump about a gallon of raw water through your toilet after your holding tank reaches empty and while the macerator is still running. This will help keep the macerator impeller from clogging between uses. Your momentary contact switch may make this a two man job or you can change the switch. That is probably your problem; that switch prevents you from easily flushing the system.

 

[JamesG161]

What is the model number and age of your macerator pump?

Jim...

 

[Peggie Hall HeadMistress]

I agree with John...replacing the tee with a y-valve should solve the problem. However, depending on the age of macerator pump, the impeller may be worn enough to reduce suction, so it may be a good idea to replace that too.

--Peggie

 

[Terry Cox]

Thanks in advance for any advice.

Hi John. Our 1991 boat's original Jabsco overboard macerator system has the same setup as yours and always works. Just a wye fitting rather than a wye valve, which works great. It becomes pretty complicated if you were to replace the fitting with a valve. Ralph provided a good check regarding any air leaking into the system through the deck fitting. A couple of possibilities to check; a clog in the pump or in the hose between the tank and the pump, or a blockage between the pump and the through hull valve.

Unlikely the tank stand pipe is leaking air as you are able to pump out through the deck fitting. If it were my boat, I would connect a city water hose to where the waste hose connects to the tank, turn the macerator pump on, then the city water, just to make sure that that pathway is clear of any clogs. Did that make a difference?

 

[JamesG161]

Pump outs depends on the Hydraulics of your boat.

If a newJabsco macerator, like my forward head, the suction or lift power depends on hold tank level and boat's water line.

Thus please provide your Model number and maker.

Jim...

 

[JamesG161]

just a wye fitting rather than a wye valve,

No valve needed.

Jim...

 

[JamesG161]

lift power depends on hold tank level and boat's water line.

Jim...

 

[sabbatical88]

Thanks everyone!

My macerator is the Jabsco 18590-2094. When I stopped getting vaccuum I installed the 18598-1000 service kit since I thought the impeller looked a little worn. That did not help. I also have a new amarine 12GPM pump, which also is not able to get suction. Ralph, I did replace the O ring in the deck which didn't help. I ran a snake from the pump-out fitting and could see it go all the way into the tank. The line from macerator to the T is also clear.

I am not sure how a wye fitting will do anything different than the current T fitting. What would be the difference?

@dlochner, what voltage should I expect when the macerator is running? It will obvously drop some below 12.8v. I think this is a good suggestion though- it is a long run with pretty high guage wire so maybe some serious voltage drop along the way. I'll try running directly off a battery.

I am attaching another picture that shows how the macerator actually sits in the boat relative to the tank and thruhull. I am pretty sure the tank is below the waterline and I know the macerator is above (with the thruhull open, no water into the exit tube of macerator). Do you think if I reduce the distance "X" in the drawing that would help? That seems fairly easy.

As for a Y or wye value, what about a simple 1 1/2 pvc ball valve from Home Depot just on the deck pump-out side of the T?

 

[Ralph Johnstone]

My macerator is the Jabsco 18590-2094.

@dlochner, what voltage should I expect when the macerator is running? It will obvously drop some below 12.8v.

Do we see a conflict here ?

 

[Richard19068]

The 12V vs 24V would sure make a difference.

@sabbatical88

Last May you had a similar problem and posted this as your solution:

"sabbatical88
May 27, 2022
After replacing the macerator for the fwd toilet and snaking the line from macerator to the T with the holding tank-deck fitting and double checking the deck cap, I was able to pump out. Whew. Yet not sure which of the things I did fixed it. I'll do an autopsy on the old Macerator and see if it was good or not. If not I'll try refurbishing it to have a spare. Thanks for all the help. I'm done with poop projects for a while, yeah!"

What is different now than then? Has it worked fine for the last 17 months and then just gone south or what?

What did you conclude when you did the "autopsy"of the old pump.

 

[Terry Cox]

Hi John. Unless I missed it, did you check the hose from the macerator through the through hull valve just to make sure there is no blockage?

 

[sabbatical88]

Last May you had a similar problem and posted this as your solution...
What is different now than then? Has it worked fine for the last 17 months and then just gone south or what?
What did you conclude when you did the "autopsy"of the old pump.

Yes, that is when I put in the amarine macerator. I recently got the service kit for the Jabsco macerator and as I replaced the impeller, I noted some wear. In august the toilet was getting serious use and that is when it started not working again. Other than that, nothing has changed. Seems like this system is right on the edge of working/not-working.
Terry- that is a good suggestion- I will check the macerator-thruhull hose, I have not done that since the trouble began.

 

[dlochner]

@dlochner, what voltage should I expect when the macerator is running? It will obvously drop some below 12.8v. I think this is a good suggestion though- it is a long run with pretty high guage wire so maybe some serious voltage drop along the way. I'll try running directly off a battery.

If the voltage drops below 12v then that could be a problem. The lower the voltage goes the less efficient and powerful the pump will be. Is there a specific cutoff voltage, maybe, but I don't know what it would be. If the voltage is dropping too low there could be several causes, the connections are poor and there is extra resistance in the circuit causing the voltage to drop, the motor is failing or the pump is failing requiring too much current to function, or the batteries them selves are getting older and have less ability to deliver the amount of current necessary for the pump to run efficiently.

The voltage is only one piece of the puzzle.

 

[Ralph Johnstone]

If the voltage drops below 12v then that could be a problem. The

The voltage is only one piece of the puzzle.

Huh ?

 

[Richard19068]

Yes, that is when I put in the amarine macerator. I recently got the service kit for the Jabsco macerator and as I replaced the impeller, I noted some wear. In august the toilet was getting serious use and that is when it started not working again. Other than that, nothing has changed. Seems like this system is right on the edge of working/not-working.
Terry- that is a good suggestion- I will check the macerator-thruhull hose, I have not done that since the trouble began.

Okay.
So are you you currently using / having problems with the 24 volt Jabsco pump or the 12 volt Amarine pump? Or are you using a 12 volt Jabsco pump? Which is it?

 

[sabbatical88]

Re 24 volt macerator: Since I am not at my boat to look at the actual model number I googled what looked like mine and reported that as the model number. Mine is almost certainly the 12volt model. I will confirm later today when I go to the boat. Sorry for the likely bad info.