Macerator Freezing Up Between Uses

[Rick D]

OK, so I have a Johnson macerator in a non-boating application emptying the contents of a 15 gallon grey water tank from a free standing portable sink. Anyhow, I have noticed that the pump will not start on the first throw of the switch. Sometimes it takes a couple to turn the shaft. I can hear the pump try to work but it just doesn't turn without several flicks of the switch.

The tank does provide some head pressure to the impeller since the tank sits above the macerator. I wonder if this might be an issue? There is no material food waste in the line.

So, I am thinking perhaps I need to lube the impeller housing. It runs fine when running and evacuates the tank easily. It has only been used maybe five or six times in a year +.

I'm putting this in the sailing forum since it's perhaps a problem this devise also has in the boating applications since that's what it's designed for.

Any thoughts from Peggy or anyone?

 

[Peggie Hall HeadMistress]

Gray and black water is sticky, so I'm thinking you need rinse out the macerator with plenty of clean water immediately after using it to dump the tank. Lubing the impeller wouldn't do much because the lubrication would just wash out in a couple of uses.

If rinsing out the pump doesn't work, you may want to consider replacing the macerator impeller pump with an electric diaphragm pump...the SeaLand T-Series pump would be the best choice.

 

[Benny17441]

Rich, you are knoledgeable in these matters. An electric motor as you may recall requires up to 5 times the amount of power required to run it. Check your source of power, connections and also the voltage drop when you flip the switch. Gray water from a sink contains emulsions from oils and soaps which will in time come together, and precipitate in globs to the lowest point which could be your macerator. It may be fighting low starting power, poor connections or a glob of thick discharge. Since you do not have any solids to churn, have you considered just using a high volume pump?

 

[Rick D]

Yea, I'm thinking a high volume pump may be the way to go. The people using the unit have been good about not putting any food parts in the sink drain. The power source is a 20 amp ac / dc quality converter with clean power. I would think that has plenty of start up power but in fact it could be a bit light since the posted draw is between 13 and 15 amps. I know Peggie is right about it being a waste to lube it. I'm just wondering if there is something I'm overlooking here. It makes no sense to me that it doesn't want to start even though there is current there and you can hear the motor hum when the switch is thrown. That why I'm wondering if water pressure on the intake side might be an issue. Hard to think it might be enough to tweak the impeller vanes causing a hard start, huh?

 

[Peggie Hall HeadMistress]

Water pressure isn't causing your problem...gray water is even stickier than black water...and what you're describing is an impeller that's getting stuck to the housing between uses. The stress needed to break it loose every time it's started again is gonna break off a vane sooner or later, and then you're gonna be back asking why it motor runs and the impeller turns, but it doesn't move anything out of the tank (it won't till the impeller is replaced).

There are two cures. Put enough clean water through it after the tank is empty to rinse it out--the tank should be rinsed out anyway...or replace the impelller pump with an electric diaphragm pump that can get stuck.

 

[hewebb]

I have one in the RV and I run water at end of pump out then put a small amount of vegetable oil in it and toggle the switch on/off quickly to get the vegetable oil in the impeller. In four years I have not had a problem. It sits in storage for months at a time.

 

[Maine Sail]

Yea, I'm thinking a high volume pump may be the way to go. The people using the unit have been good about not putting any food parts in the sink drain. The power source is a 20 amp ac / dc quality converter with clean power. I would think that has plenty of start up power but in fact it could be a bit light since the posted draw is between 13 and 15 amps. I know Peggie is right about it being a waste to lube it. I'm just wondering if there is something I'm overlooking here. It makes no sense to me that it doesn't want to start even though there is current there and you can hear the motor hum when the switch is thrown. That why I'm wondering if water pressure on the intake side might be an issue. Hard to think it might be enough to tweak the impeller vanes causing a hard start, huh?

Rick,

This is likely your problem. Connect it to a battery and I would nearly guarantee your issues go away. That little converter simply can't deliver the in-rush current needed...

 

[Benny17441]

Keep an open mind and don't hone in into what could be an unlikely cause, I don't think water presure could be preventing the pump from starting . Maine could be right, I had missed the part where you are running a converter. I would definitely connect it to a fully charged battery to clear once and for all any issues about low power. My question to you now is, how can you be sure they are not putting any solids in the drain? After all you are probably looking at the gray water after it passes the macerator.

 

[Rick D]

Benny, Sounds Right To Me Too..

Keep an open mind and don't hone in into what could be an unlikely cause, I don't think water presure could be preventing the pump from starting . Maine could be right, I had missed the part where you are running a converter. I would definitely connect it to a fully charged battery to clear once and for all any issues about low power. My question to you now is, how can you be sure they are not putting any solids in the drain? After all you are probably looking at the gray water after it passes the macerator.

You are correct, Benny. I don't know really, I just think I know. This is in a yacht club, so I don't see what goes down the drain all the time, but they do seem to be good about it.

I just changed out the AMG battery on my wife's Miata. It's OK but weak. I'm going to try it between the converter and the load. I have an idea that Maine and you are dead on as to the cause. I have seen the macerator jump to 25 amps on initial start up on my boat, so maybe it's just the start up jump that's doing it since it runs like a champ after it is going.

 

[Rick D]

That Was It...

...it appears the start up spike amps of the macerator was more than the capacity of the 12 volt converter. So, I put the old AGM Miata battery in between the converter and 12 volt pumps and it works like a charm.

This is a bit of a hillbilly set up tho since the converter isn't a charger, but with 13.8 volts going out, it will bring up that AGM just fine in between uses. I think.

 

[artboas]

This will solve it

...it appears the start up spike amps of the macerator was more than the capacity of the 12 volt converter. So, I put the old AGM Miata battery in between the converter and 12 volt pumps and it works like a charm.

This is a bit of a hillbilly set up tho since the converter isn't a charger, but with 13.8 volts going out, it will bring up that AGM just fine in between uses. I think.

Hi Rick,

Arthur here. Glad you're still enjoying the 40.5. I miss mine a bit, but love my new Hunter!
What you can do is wire a honking big electrolytic capacitor across the motor. This will give you a ton of startup current for just enough time to get the pump spinning, and overcome the inrush current of the motor. Put the capacitor right a across the pump wires, and that will make sure losses are minimal.
By the way, the power supply you are using is probably a linear supply, which does have a certain amount of output filter capacitance. The problem is that the pump is an inductive load, and it will easilly "swallow" the charge built up on the capacitors. To run this pump from a supply without startup hiccups, you would likely need at least a 20A supply.
Good luck

Arthur