Macerator Pump - Dumping Waste Material

[Ron]

I have been searching and talking with RV Service Technicians for information regarding the Macerator Pump. I wonder if the following could be the correct information concerning blockage of a Macerator Pump.

What I have been told Material from the Sewer Outlet must be able to Flow/Gravity Feed to the Inlet of the Macerator Pump. Level or a Slope to the Inlet of the Macerator Pump is fine.
Material from the Sewer Outlet must be able to Flow, Gravity Feed to the Inlet of the Macerator Pump. The action of the Macerator Pump grinds the waste as it enters the inlet of the Macerator Pump.

A: To dump Material from the Black Tank, if the RoadTrek is Level or on a Slope being Facing Down, Gravity will properly Feed Material to the Inlet of the Macerator Pump.

B: If the RoadTrek is on a Slope/Incline, Facing Up, Material from the Black Tank will not be able to Flow properly to the Inlet of the Macerator Pump with Gravity Feed, a sufficient amount of Material being Toilet Paper, Feces, Urine and Water will stay in the Black Tank.

Black Tank will not be completely emptied and could cause the Toilet Paper to Clog the Inlet of the Macerator Pump.

I would believe that thinking the Black Tank is completely emptied the Urine and Water is not pushing, (Gravity Feed) the Feces and Toilet Paper completely through the Inlet of the Macerator Pump and out of the Macerator Pump Outlet, and the Toilet Paper stays and clogs the Inlet of the Macerator Pump, which causes the blockage.

When dumping it is important that the RoadTrek is Level or on a Slope, front end facing down, suggestion made to me from a RV Service Rep is to have the rear tires on leveling blocks, making the rear of the RoadTrek higher than the front.

Also the Black Tank should be completely full with water before dumping, after dumping again fill Black Tank to the top with water, then dump, after this dump put in 2 - 3 gallons of water along with proper chemical treatment to break down the RV 1 ply toilet paper and feces.

Checking my RoadTrek's Black Holding Tank bottom and Macerator Pump Inlet bottom on Level Ground in my garage the following Approximate Measurements were taken.

8" Ground to Bottom Rear of Black Holding Tank

6 3/4" Ground to Bottom Front of Black Holding Tank

5 3/4" Ground to Bottom of Macerator Pump Inlet

Ron,

[markopolo]

"RV techs" and "macerators" could be part of the problem.

Think boats.

You don't gravity feed waste into a macerator on a boat. Check the specs. I think all macerator pumps will suck waste up a few feet. No need for gravity. Mount the pump on top of the tank. Then you can have two options. Gravity through a 3 inch hose or pump it out through the top.

[Ron]

Mark,

I found the following also will contact SHURflo:

Step #4
Install macerator in compartment with sewer outlet for motor homes and under frame for travel trailer and fifth wheel applications. When installing macerator be aware material from sewer outlet must be able to flow to pump with gravity feed. Do not mount macerator above outlet.


Would you be able to found out any info if Gravity Feed to macerator pump is need?

[Ron]

Mark,

Thanks for posting my Signature.

[markopolo]

Originally Posted by Ron

Mark,

I found the following also will contact SHURflo:

Step #4
Install macerator in compartment with sewer outlet for motor homes and under frame for travel trailer and fifth wheel applications. When installing macerator be aware material from sewer outlet must be able to flow to pump with gravity feed. Do not mount macerator above outlet.


Would you be able to found out any info if Gravity Feed to macerator pump is need?

That has to be from something to do with retrofitting RV's.

I'm really glad you brought this topic up. Macerators will suck waste up from a tank. I'm not smart enough to think that up. I must have read it in product specs.

I'll post what I find.

[markopolo]

SHURflo

Pump is self-priming to a five-foot lift
when impeller is wet, four foot lift when impeller is dry.

http://www.shurflo.com/files/Education- ... %20001.pdf

Jabsco

Self priming to 5ft this pump will empty a typical 30 gallon (115 Liter) holding tank in less than 3 minutes.

[Ron]

Just posted on RV.net:

Yes, a macerator pump will grind waste & PUMP it long distance & up hill.

BUT it has very little 'suction' power...therefore the inlet side of pump needs a good gravity feed & lots of water ( which is needed even when using the standard 3" hose).

Ron

[markopolo]

5 feet of suction.

More than adequate. Mount the pump on top of the tank.

In a retrofit, you can't really do that. I hope Roadtrek reads this. They could give owners two option at little additional cost. Pump it out or let it drain.

[Mike]

They're great when they work? (we've had that discussion before)
I think the macerator is a great idea (in theory?), but the fact that we're even discussing them, leads
me to believe that maybe in a smaller RV, where the waste systems aren't always easy to get at because
of space constraints which require them to be located mostly underneath the van, they aren't a perfect
solution. Hard to get at to resolve problems like clogs. In a larger RV they might be a better solution.
I think if I were designing a class B, I'd be considering hassle versus reward. I'd probably have considered
a better gravity fed dumping system that was positioned for greater accessibility, and maybe added a
better flush out setup of some sort, rather than add a machanical device which appears to be less than
effective. and apparently less reliable.
Hindsight, I know.

[Johnny R]

Is there an advantage to macerating pump? I know in the home setups one has to be careful what is flushed down. Only poop.

[Mike]

Originally Posted by Johnny R

Is there an advantage to macerating pump? I know in the home setups one has to be careful what is flushed down. Only poop.

Apparently not. It appears Roadtrek added it because others did, I'd guess. Seems problematic in some cases,
and in my opinion, the cheapest and most effective fix would seem to be remove it and replace it with a (better?)
gravity feed system.

[Ron]

Believe RoadTrek is the only one who installed the Macerator Pump, Pleasure-Way did not install the macerator pump, they have the gravity feed using the sewer hose.
Wish I could replace the macerator pump, unable to do so, no room underneath.

[markopolo]

If you can't go back to gravity dumping through a 3" hose then we need to figure out why your macerator has failed to work properly.

1. Check the wiring. Maybe hold a camera up under there and take lots of photos. Hopefully you'll be able to see the writing on wiring. It needs to be able to handle 20 amps with little or no voltage drop.

In my first experiment with macerators I used some 18gauge wire I had. It was useless. I'd blow the 20 amp fuse. I replaced that wire with 10 gauge - no more blown fuses.

2. Maybe pump out a little bit of gray water first to wet the pump. Then dump the black and finish with gray tank.

3. I suggest running the van motor when using the macerator when possible. The pump will see 14 volts instead of 12 volts or less. If you've been camping a few days your batteries might be discharged a bit and if stop at the dump station on the way out the batteries won't have had time to recharge. The macerator could easily blow the fuse if the battery is low. If it is very cold out then your battery voltage will again be lower.

You'll solve this problem.

[Ron]

Good suggestion, although SHURflo said to dump the black tank first, then the gray tank.

[markopolo]

Black first, then gray should work. That's the normal way of doing it.

Maybe 1 or 2 seconds of gray................ You want to make sure you have enough gray left to clean everything out.

I liked using my self-installed macerator on my Roadtrek. My favorite campground had a high curb around the dump site. It was about the same level as the lowered RT black pipe. It was a real nuisance "walking" the waste through the blue hose up over the curb. The macerator solved that.

Most dump sites don't have that problem.

[Ron]

That is what I would do have I had the sewer hose, use a portable macerator pump instead of the permanent macerator.

[Mike]

Have you sought a second opinion about retrofitting a gravity system in place of the macerator? Maybe someone
else knows an inventive way to get around the clearance issue? Google might turn up something, or RVNet?
It really sucks that you spent that much money, and didn't get exactly what you want.

[Ron J. Moore]

I don't know if this helps - I installed a macerator on my 05/04 RT190P and it has been problem free since installation about 5.5 years ago. Took about 4-5hrs to finalize and test. We only use it for "fluids" and it has worked flawlessly. Bought all the items thru RV-Sani-Con and followed the installation of a fellow Trekker. Safe travels.

[Ron]

Hi Ron,

Good for you having no problems, and using it for only fluids, take it you must use the campground bathrooms.

We will not dispose toilet paper in the toilet use a plastic bag which is in a container with a cover.

http://i879.photobucket.com/albums/ab35 ... posal8.jpg

Ron

[yizit]

We purchased our 04RTC190P last March 2010. The original owner had a macerator pump installed. Shortly after we purchased the RT, we are 3rd owners, we had to replace the hose and shortly there after the mascerator pump went. I did an extensive search on the web about mascerators, and one of the things I read was it was very important to add at least 1 gallon of water with chems into the emptied tank. The biggest problem with blockage is the lack of adequate water to start the breakdown of "matter", just urine is not enough. When we dump our tank, I notice the first couple of seconds of "matter" is clear water then cloudy water. We are fortunate to have our own dump system at home, so we are able to take our time and do a good job of flushing out the tank. We are not immune to toilet paper obstructing the sensors and causing us a false reading on the panel. Another thing we use, after another extensive search on the WWW, is http://www.5starhappycamper.com/compare.html. We've used the "other stuff" in our TT's and didn't like the chemical smell. It breaks down "matter" and there is NO odor (we use 2 ply paper). Our dump system is not ground level, it is about 6" above ground (poor planning on our part), and we have no problems with the pump pumping up and over to empty.