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Old 10-16-2012, 08:40 PM   #1
Ron
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Default Macerator - Metal Impeller -vs- Polyurethane Impeller

Looking for opinions.

Two blades on the Impeller of my ShurFlo 3200 Macerator Pump of my 2010 RoadTrek have broken off, the Impeller is made out of Polyurethane, the blades are believed to be Rubber.

I have to either replace the Impeller or the Macerator Pump, of course cheaper to replace the Impeller.

There are Macerator Pumps that have a metal Impeller, would like opinions of a Metal Impeller -vs- a Polyurethane Impeller.

Ron


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Old 10-16-2012, 09:32 PM   #2
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Default Re: Metal Impeller -vs- Polyurethane Impeller

If you can find one then it should work. I think a flexible impeller is required for a self-priming pump. In your Roadtrek gravity gets the waste to the pump. The pump only has to chop it up and pump it out.

Are there any macerator pumps with a metal impeller available? I think you had a couple of quotes from RV places - can you post the brand and model number of the pump so we can look it up.

If you can't find a macerator pump with a metal impeller then maybe try a Globe brand blue 15 minute run dry impeller as a replacement. http://www.globecomposite.com/pages/products_impeller
I think the part # for the Globe replacement for ShurFlo is 01-12-0960

The Globe impeller would be worth a try at around $20.

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Old 10-16-2012, 10:37 PM   #3
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Default Re: Macerator - Metal Impeller -vs- Polyurethane Impeller

The cutting blades are stainless steel in your ShurFlo.
The impeller vanes are a flexible material.

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Old 10-17-2012, 12:25 AM   #4
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Default Re: Macerator - Metal Impeller -vs- Polyurethane Impeller

I received the following from Camping World:

We do have a Macerator pump that has metal impeller flaps. This is item number 7232. Please let us know if you have any other questions you may have.

Thank you,
Camping World Customer Care

ALSO:

You mention: In your Roadtrek gravity gets the waste to the pump. The pump only has to chop it up and pump it out.

SO IT TAKES GRAVITY FOR THE WASTE TO GET TO THE PUMP, ARE YOU SURE?

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Old 10-17-2012, 12:53 AM   #5
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Default Re: Impeller & Metal Cutter Blades Question

On my 2010 RoadTrek does the Grey/Black tank waste/solids first enter into the Metal Top/Bottom Cutter Blades housing, waste/solids chopped up, then exit to the Impeller, and out of the Impeller housing?

Or does the waste/solids first enter into the Impeller housing and chopped up.

I feel it first enters and chopped up by the Metal Top/Bottom Cutter Blades.

It is mentioned that Gravity feeds the waste solids into the Macerator Pump, take it then the Macerator Pump does not SUCK out liquid from the Grey Tank, nor the Black Tank.

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Old 10-17-2012, 01:42 AM   #6
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Default Re: Macerator - Metal Impeller -vs- Polyurethane Impeller

When I look up that Camping World item: http://www.campingworld.com/shopping/it ... 7232#specs
I see that it is a Xylem / Flojet / Jabsco product 18550-000 series with a flexible Nitrile Compound impeller which is a type of rubber as far as I can tell. It has metal cutting blades just like your ShurFlo.

Link: http://www.absak.com/catalog/product_in ... cts_id/215

Sorry, I can't say I'm 100% sure about gravity and the pump. I've never had the pleasure of working on a Roadtrek with one
It sure looks to be gravity fed as shown by the Roadtrek drawings in the manual though. The macerator pump is below the waste tanks.



The Globe impeller listed above must be many times more durable for the manufacturer to claim 15 minute run dry ability. Is it a 15 second run dry rating on the ShurFlo?

If you work on the pump yourself then all bets are off re: warranties but I think you might be past that point anyway.
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Old 10-17-2012, 01:51 AM   #7
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Default Re: Impeller & Metal Cutter Blades Question

Quote:
Originally Posted by Ron
On my 2010 RoadTrek does the Grey/Black tank waste/solids first enter into the Metal Top/Bottom Cutter Blades housing, waste/solids chopped up, then exit to the Impeller, and out of the Impeller housing?

Or does the waste/solids first enter into the Impeller housing and chopped up.

I feel it first enters and chopped up by the Metal Top/Bottom Cutter Blades.

It is mentioned that Gravity feeds the waste solids into the Macerator Pump, take it then the Macerator Pump does not SUCK out liquid from the Grey Tank, nor the Black Tank.

Ron
Waste hits the cutting blades first.
The impeller would draw waste through the blades quicker than gravity would allow. So it's a bit of both; gravity and suction.



Edit: Ok thinking about it some more......... gravity would get waste to the macerator unless an air lock is created somehow. I don't really think that would happen.
There would be air between the waste valves and the macerator after emptying the tanks. Next time you dump that air would have to escape up into a waste tank or out through the macerator. I think that small amount of air would go out the macerator.

I've gone full circle on this...... maybe...... to avoid a flexible impeller and suction you'd need a macerator pump that uses centrifugal force to push the waste out through the hose which would create suction anyway ........
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Old 10-17-2012, 11:16 AM   #8
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Default Re: Macerator - Metal Impeller -vs- Polyurethane Impeller

I can tell you that there is good suction from those macerator pumps. The '04 Roadtrek I had did not come with a macerator and I first tried a portable one connected to the 3" blue hose. On the initial test of the system I very briefly closed the waste tank valves once with the pump running........ and watched the portable pump quickly slide toward the van as the air was sucked out of the slinky hose I didn't do that again and still remember it 7 years later!
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Old 10-17-2012, 03:37 PM   #9
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Default Re: Macerator - Metal Impeller -vs- Polyurethane Impeller

Marco's comment about what is between the dump valves and the pump inlet is a point that I have always thought could be a major contributor to long or short life of the macerator. When the tanks are empty, you have air there. If you close the valves and go merrily on your way after putting a little water and treatment in your tank, the air is still there. It is also allowing the "stuff" that is still around the parts of the pump to dry out and solidify. When you again go to dump, you have pump with dried out sludge in it, and air in it, but nothing to lube and cool it, like liquid. The impeller could stick and tear, or if it breaks loose right away, it could overspeed because of no pumping resistance and overheat the impeller. The first thing to hit the pump is going to be the heaviest stuff from the bottom of the black tank, which might not be very good to do if it is running too fast.

What we do, and recommend, is, once the tanks are empty (with a grey to black backwash dump procedure), and maybe a couple of buckets of water dumped and pumped out from the black tank, mix up a gallon of water with Happy Camper at a bit higher concentration than for tank use. Poor it into the toilet, with the dump valve closed, and then open the black valve for a few seconds. You will hear the water fill the piping from the tank to the pump. Close the dump valve and add your regular water/additive to the black tank.

By doing the above, you help the pump in several ways. There is no air in it, so the sludge won't dry out. You have Happy Camper in the pump to help digest and break down and leftover stuff. The plumbing is full, so the pump won't overspeed, or run dry for any time at all. All the parts are lubricated and cooled with the water from the first second of running. All good things IMO.

We have done this for the last couple of years, after hearing of macerator problems, and have not had any problems yet. The pump always starts instantly, with no change in noise until the tank is empty. I will be pulling our pump out to check it this winter, as we will be traveling much more next year, and it is from 2007, so it will be interesting to see how it has survived.
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Old 10-18-2012, 01:46 PM   #10
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Default Re: Macerator - Metal Impeller -vs- Polyurethane Impeller

Would placing the macerator upright be a better way to do it? It would still dry out with infrequent use but residual water / scum / bits would drain away from the impeller.

from phrannie.org - macerator is "A" in the image

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