Macerator - Metal Impeller -vs- Polyurethane Impeller

Ron · 10-16-2012, 08:40 PM

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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markopolo · 10-16-2012, 09:32 PM

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.

markopolo · 10-16-2012, 10:37 PM

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

Ron · 10-17-2012, 12:25 AM

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?

Ron

Ron · 10-17-2012, 12:53 AM

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

markopolo · 10-17-2012, 01:42 AM

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.

markopolo · 10-17-2012, 01:51 AM

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 ........

markopolo · 10-17-2012, 11:16 AM

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!

booster · 10-17-2012, 03:37 PM

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.

markopolo · 10-18-2012, 01:46 PM

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

booster · 10-18-2012, 05:58 PM

Quote:

Originally Posted by markopolo

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

It would have to lift the effluent more that way, and would get air sooner, but maybe.

On the question of gravity feed or suction (lift). The only way to tell is to put a pressure/vacuum transducer at the inlet to the impeller or as close to that as possible. You can, however, make a good guess with a little experiment.

1. put water in your tank and pump it out with the macerator. Watch how far it squirts and how long it takes to empty.

2. take apart a macerator and use the inlet end of it only on the end of the tank drain. No guts, choppers or impeller, just the restriction of the inlet fitting.

3. Put water in again and gravity drain the tank through the new configuration.

If it took longer and didn't shoot water as far, the flooded inlet can't supply water as fast as the pump needs it. To get the water in adequate quantity, the pump will pull a vacuum on the water, and thus be in a suction/lift condition. If the tank drains as quick as before, there is no suction at the inlet.

Mike · 10-20-2012, 04:24 PM

kinda makes you wonder if it's really worth it. i like pulling the valve handle, and hearing nothing but the satisfying sound of rushing waste water as it makes it's way downstream. no mechanical pump thrum, or macerator noises to scrutinize and analyze for proper functionality. that is, until i use my toilet's flush handle after midnight, and hear the ShurFlo struggle to self prime as the motor kicks in, and tells me all is well in the pex plumbing world.
and that, is a reassuring sound in a class B camper. to me, at least.

arrveedogz · 10-20-2012, 06:26 PM

Quote:

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

I've definitely had occasions where I 'pumped air,' as I can see the hose jerking around and watch spurts of material through the translucent elbow above the discharge valve. When I see this, I stop pumping, wait a few and start the pump again. It usually seems to run more smoothly immediately afterwards. In my naive imagination, I suspect a bit of gravity drainage at work, with stuff in the tank settling back down once the turbulence due to macerator 'suction' stops.

If you follow the gray-after-black dumping practice, it would seem that you're rinsing the blades with soapy water when they need it most. I always run some gray first, with the idea of pre-wetting the blades and pre-lubing the hose with soapy water. And lately I've been running a couple of gallons of clear water into the black tank after dumping and then dumping that.

It's ironic that this delightful task signals the end of an otherwise pleasant and recreational activity.

markopolo · 10-23-2012, 09:04 PM

If you are a Roadtrek owner that stumbles across this topic - consider joining the Roadtrek Yahoo Group : http://autos.groups.yahoo.com/group/roadtrek/
11 years of great info on that site

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Macerator waste pumps have advantages and disadvantages. They don't fail often but they can stop working leaving you unable to empty your waste tanks. If you are on day 3 of a one or two week long vacation and hundreds of miles away from a repair facility then that pump failure could be a real inconvenience. I've periodically seen WagBags mentioned on the Yahoo group above.

Quote:

Our toilet kit is the ONLY biodegradable solution that traps, encapsulates, deodorizes and breaks down waste with a NASA-developed gelling agent. Use it, seal it and toss it as normal trash.

Usually, I see WagBags mentioned as a solution to winter rv'ing when you don't want to put water that can freeze into the waste tank of your RV. However, it might be a good idea to keep a couple of these kits in your camper van just in case your macerator waste pump ever fails and your waste tank is full. I've seen them at Princess Auto in Canada for $2.99 each and Cabela's in the US has 12 packs for $39.99

Sorry, I went a little off topic - back to the macerator repair.

Mike · 10-24-2012, 02:11 AM

Why not cut a hole in the middle of a small stool (sorry) and just use Wag Bags? Who needs a loo, when these bags will do? No macerator related muss or fuss?
Spare you and your loved ones the terror and embarrassment which accompanies a macerator failure in the middle of a crowded campground.

Sir Isaac Newton knew there was only one truly infallible answer to RV dumping.

(sorry, it's been one of those days

pardon the off topic intrusion

)

markopolo · 10-24-2012, 12:54 PM

It rhymes too! The puns are unavoidable on this forum

Injecting humor into this helps. Finding the positive in any situation helps also. I saw posts by WVvan and stan909 on RV.net not long ago. Both had mechanical failures on their vans - brake failure and radiator fan came apart - major stuff. Both were very happy to report that it happened at home and not on the highway. They only saw the positive and just dealt with the repairs.

Ron must be working on a fix. Over the last 8 years or so that I've read his posts he has presented some interesting solutions. I suspect some people misinterpreted his matter-of-fact writing style which probably was developed from writing many police reports during his career as a police officer.

I can think of two disadvantages with having a macerator:
1. it can fail leaving you unable to dump waste
2. you can't leave the gray tank valve open when enjoying a long shower in the van

The advantages I can think of are:
1. not as messy - no dripping 3" hoses to compress into a storage tube
2. you can empty the tanks in situations when gravity presents a problem
- at home, up over curbs, long distances
3. access to emptying the tanks is easier (particularly if you have a knee, hip or back problem etc.)

Mike · 10-24-2012, 01:21 PM

Don't forget the relative costs of each option. Dump hoses, gate valves, and gravity are (almost) free.
Macerators are expensive to include in the original equipment, to install afterwards, to repair, and to replace, if you're not a DIY-er.

I do tend to crunch the $$ numbers as well as the mechanicals.

As for pumping waste up hill, or when conditions make it awkward to use gravity, perhaps a portable macerator for those situations might work?

markopolo · 10-24-2012, 01:56 PM

Good point Mike.
Both systems have the same black and gray tank valves.

DIY impeller replacement - maybe $25
Dealer would probably suggest pump replacement (you know - why put the old pump back on etc. ) - maybe $500 installed

It would be great if a current RT owner would document a step-by-step macerator impeller replacement and share it amongst all the groups / forums. Like Harvey Tetmeyer use to do: http://www.roadtrekchapter.org/mods/

booster · 10-24-2012, 04:23 PM

Quote:

Originally Posted by markopolo

Good point Mike.
Both systems have the same black and gray tank valves.

DIY impeller replacement - maybe $25
Dealer would probably suggest pump replacement (you know - why put the old pump back on etc. ) - maybe $500 installed

It would be great if a current RT owner would document a step-by-step macerator impeller replacement and share it amongst all the groups / forums. Like Harvey Tetmeyer use to do: http://www.roadtrekchapter.org/mods/

I will be pulling our macerator this winter to check it out before we head out next summer on much longer trips. We have had no trouble, but I want to see if our early dumps, where we probably pumped too long, have done anything bad. It will also give me an idea as to if we should carry a spare pump, or cutters and impeller when we go out of the way places like Alaska in the future.

Ron · 10-24-2012, 10:06 PM

I figured it is best to replace my macerator pump with a new one, of course it will cost about $500. Meantime I will be using our old Porta Potti that we have had for years, it is in good shape, is reliable.

Concerning a problem I could have with the macerator pump he stated that the voltage to the macerator should be checked, may be a poor connection that is dropping the voltage which will make the macerator work a lot harder.

I also have been thinking of installing a Porta Potti permanently one individual sent instructions on how to remove the current toilet and cap the hole so that the Porta Potti can be installed in place of the toilet.

I was also told there is a custom hold down kit with heavy duty brackets, available special order to secure the Porta Potti, how do I get further information on a custom kit?

Ron

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