macerator not emptying holding tank

[ktdtx]

I replaced our macerator pump with a Sealand diaphragm pump and haven’t had any issues since.

YES!


I had a similar, recurring problem which required aggressive back flushing from the thru hull--redid the system with PVC and more appropriate sized and type hose. Also replaced Jabsco macerator with Sealand and then NO MORE problem.


I might have an idea that the seller knew there was a problem.


Ken

[Swfla]

Originally Posted by menzies

Did you open the deck cap? If not try that in case the vent is clogged. Air needs to get in to replace the water.

There was a recent thread about a tank split because the vent was clogged and the vacuum of the pump crushed the tank.

[Alaskan Sea-Duction]

Originally Posted by menzies

That PVC T is a Y valve! (not a lot of difference in the letter!).

Make sure the leak is between the macerator and the through hull, if it is on the holding tank side of the pump it may be causing your problem.

Originally Posted by jclays

when i bought the boat the holding tank had waste in it. It did not empty then. The delivery captain had it pumped out and cleaned. The cabin of the boat had some odor so i put water and bleach in the holding tank to hopefully eliminate some of the odor. there is a PVC Tee at the bottom of the holding tank. One hose goes to the deck fitting the other side of the Tee goes to the macerator pump. No Y valve. The hose from the out put hose from the macerator to the seacock is wet and is leaking discovered after looking around a few days ago. Before my purchase the boat sat unused for about 6 months.

Your macerator pump is sucking air. Either the impeller is shot or as I found mine a few days ago the pump bolts/screws that hold the impeller onto the pump. Replace the pump. They are about $200 at WM.

Originally Posted by jclays

It’s actually just a white PVC T. It is not a valve in anyway. You cannot isolate the macerator or the deck pump out like a true y valve.

I am surprised the surveyor let that go., but if you look at it it works for pumping waste from the tank. Not sure if pumping from the deck can damage the macerator.

My black tank has one inlet and two outlets. One for pumpout through the deckfill and one for the macerator.

[timb]

Originally Posted by Alaskan Sea-Duction

I am surprised the surveyor let that go., but if you look at it it works for pumping waste from the tank. Not sure if pumping from the deck can damage the macerator.

mine is the same way but it has the cap on the deck fitting and the seacock on the pump should work fine . but mine doesn't work so i can't say .i i don't plan on using mine much but the hoses to the deck and pump are the only one left to change so i want to change the pump at the same time. i am dreading taking the lowest hoses on the tank off.

[Fletcher500]

My Jabsco Masc Pump is going in to the trash when I get back and will be replaced with a Sealand based on the comments here.

Edit: KTDX: how did you back flush through the thru hull?

[AusCan]

For emptying a holding tank, a macerator pump is the 3rd best option. They are expensive and unreliable. A diaphram pump is better.
I find the best solution is gravity. Mount your black water tank above the water line and just open the drain valve to empty.

[High Wire]

The deck fitting has an O-ring that if cracked will cause your problems. Very easy to check!

[bligh]

Originally Posted by jclays

when i bought the boat the holding tank had waste in it. It did not empty then. The delivery captain had it pumped out and cleaned. The cabin of the boat had some odor so i put water and bleach in the holding tank to hopefully eliminate some of the odor. there is a PVC Tee at the bottom of the holding tank. One hose goes to the deck fitting the other side of the Tee goes to the macerator pump. No Y valve. The hose from the out put hose from the macerator to the seacock is wet and is leaking discovered after looking around a few days ago. Before my purchase the boat sat unused for about 6 months.

Ok since the pump out fitting/line is connected to the macerator line, make sure the deck fitting of the pump out has a good o-ring and is sealed tight. Otherwise the pump will not prime with effluent.

[mahal]

Originally Posted by timb

mine is the same way but it has the cap on the deck fitting and the seacock on the pump should work fine . but mine doesn't work so i can't say .i i don't plan on using mine much but the hoses to the deck and pump are the only one left to change so i want to change the pump at the same time. i am dreading taking the lowest hoses on the tank off.

In case you weren't aware, you can apply vacuum to the tank to keep remnant black water from from coming out when replacing the hose. Attach a shop vac to a fitting on the tank's top, like the fitting for the hose from the head. Plug the vent line and any others that might allow air in. Turn on the shop vac and swap hoses.

BTW, discharge hoses that attach to the bottom of the tank (instead of the top with a dip tube) are subject to premature permeation since it's always full of crap. A workaround solution is to install a rigid sched.40 PVC pipe installed vertically or close to it up to the tank's top (external dip tube?) before the flex sanitation hose. Better yet, use PVC for as much as you can if you have straight runs.

If you're upgrading to a diaphragm pump, with your plumbing set-up, which is similar to mine, make sure that your discharge valve is always closed when at the pump out. Or the duckbills in the new pump might invert rendering it inop until corrected. Don't ask me how I know.

[mvweebles]

Last year when I was getting ready to leave San Francisco for Ensenada (a 75-hour non-stop run with myself and two crew ---- and one head), my macerator died (more accurately, it died a while back, just decided now was the time to replace). I got a new Jabsco from Defender. I installed - it would run and make a gurggling sound like it was emptying the holding tank, but then not actually move anything. I figured it must be an install error or something related to the boat sitting for a few years. I spent 1-1/2 days checking current, breakers, everything I could think of. Man, what a mess - I re-installed the dang thing a couple times.

Finally I bought a brand new one at West Marine's shylock prices. Worked like a champ! The original Jabsco was DOA. I sure wish I'd figured that out several-manhours earlier. It really bummed me out - I was trying to figure out what to do with three persons onboard for 3-days. Not like I could go headless.....

Hope your experience is better than mine. Made me think long and hard about a composting head.......

Peter

[jclays]

What is a diaphragm pump? I am not familiar. Can you give me a brand/model so that I may research.

I will install PVC ball valves after the PVC T to be able to isolate the macerator from the deck pump out.

[mahal]

Originally Posted by jclays

What is a diaphragm pump? I am not familiar. Can you give me a brand/model so that I may research.

I will install PVC ball valves after the PVC T to be able to isolate the macerator from the deck pump out.

Look up Dometic Sealand discharge pump.

Your plumbing set up is fine. My boat is plumbed the same way. As long as there’s a valve or seacock and it is closed when at the pump out it should be fine.

Like others have suggested, make sure that you don’t have a vacuum leak at the deck fitting by making sure the lid o-ring is in good shape.

[jclays]

The delivery captain had the boats tank pumped out and cleaned. The seasick was open . Would that damage the macerator? It runs fine it just doesn’t pump the tank of water out.

[Swfla]

Lack of use is a likely culprit. You're only guessing until you get in there and see with your eyes. A shop vac will suck up any small amount of bleach water that might seep out. Can you get to it before the weekend?

[mahal]

Originally Posted by jclays

The delivery captain had the boats tank pumped out and cleaned. The seasick was open . Would that damage the macerator? It runs fine it just doesn’t pump the tank of water out.

Which type of discharge pump do you have? I know you call it a macerator, but some folks call their discharge pumps that even if it's really a diaphragm type. If it's the latter, there is a chance that the duckbills are inverted and will need to be straightened or replaced. If you have the macerating type, I don't think vacuum going through it did any harm - but I'm not certain.

[High Wire]

Originally Posted by jclays

The delivery captain had the boats tank pumped out and cleaned. The seasick was open . Would that damage the macerator? It runs fine it just doesn’t pump the tank of water out.

Running a true macerator pump dry (or without flow) for more than a minute will destroy the impeller. Not knowing the history consider the impeller toast

[timb]

mahal thanks for the vacuum tip .

i looked up the 300 $ sealand pump there instructions are contradicting themselves they say you need a vented loop/siphon break between and the thru hull ? that would damage the duck bill like the seacock open .but on there same instructions the diagram does not show one?

[Woodland Hills]

Originally Posted by timb

mahal thanks for the vacuum tip .

i looked up the 300 $ sealand pump there instructions are contradicting themselves they say you need a vented loop/siphon break between and the thru hull ? that would damage the duck bill like the seacock open .but on there same instructions the diagram does not show one?

I installed mine as a direct replacement for a GalleyMaid macerator with no siphon break. Just a direct hose from the tank to pump and from the pump to seacock, works just fine for the past 9 months.

[mahal]

No vented loop on mine either.

[jclays]

Do the diaphragm pumps work with a vacuflush toilet?