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Macerator woes

Wolfe Smythe

Wolfe Smythe

New Member
I am having issues with my macerator. Should it be able to empty the holding tank? Does the inlet tube go to the bottom of the tank? I seem to be able to empty the line but not the tank. Maybe it's just the pump that needs a rebuild.
 
Most macerator pumps are self priming up to about 4 to 6 feet of vertical distance. As macerators age or become clogged with debris they loose the ability to self prime. .Typically the cutting blades / impeller on macerator pumps are serviceable & replaceable. Best to identify the brand and model you have then look up specs on line. You should be able to determine the macerator's original ability to self prime and if the unit is serviceable.

Ideally macerator pumps are located at the same level or below the base of the holding tank. Obviously this is not possible in M38x with the holding tank in the lower portion of the keel.

When I disassembled Pilgrim's (1979 M382 hull#115) original holding tank the discharge was a PVC pipe. The end of the pipe was slightly above the floor of the tank. Thus it would be impossible to empty the last inch or so of waste from the tank.

What are you defining as "the line"? Is this the run of hose between the macerator and the holding tank pick up? The run of hose between the macerator and the thru hull? Both? What makes you think you are clearing the line?

Are you certain the holding tank is not empty?
 
svpilgrim said:
Most macerator pumps are self priming up to about 4 to 6 feet of vertical distance. As macerators age or become clogged with debris they loose the ability to self prime. .Typically the cutting blades / impeller on macerator pumps are serviceable & replaceable. Best to identify the brand and model you have then look up specs on line. You should be able to determine the macerator's original ability to self prime and if the unit is serviceable.

Ideally macerator pumps are located at the same level or below the base of the holding tank. Obviously this is not possible in M38x with the holding tank in the lower portion of the keel.

When I disassembled Pilgrim's (1979 M382 hull#115) original holding tank the discharge was a PVC pipe. The end of the pipe was slightly above the floor of the tank. Thus it would be impossible to empty the last inch or so of waste from the tank.

What are you defining as "the line"? Is this the run of hose between the macerator and the holding tank pick up? The run of hose between the macerator and the thru hull? Both? What makes you think you are clearing the line?

Are you certain the holding tank is not empty?
Click to expand...

Thanks for the info
I know the specs of my pump and it is supposed to have a 5 ft lift, and it is serviceable though 34 years old so I may just replace it as opposed to putting a kit in. By the line I meant the line from the head and the waste line to the tank. The pump seems to load up and sounds like it's working then pulses. In retrospect that seems like it's losing it's prime. My main question was how far down does the tank inlet go. From what I gather from your feedback both they discharge (to deck fitting) and inlet (from head) reach the close to the bottom of the tank. If it is indeed within an inch of the bottom then it is most likely just a bad pump.
 
A new macerator should fix that , or mail it to Depco pump co Clearwater fla they fix pumps ! They do Disney's pumps , They run all there rides on water. Great people !
 
Make sure that the hose to the deck pump-out is not porous. I needlessly replaced a macerator when it wouldn't hold a prime. Same problem with the new macerator until I replaced the hose. I didn't suspect the hose because there was no noticeable odor. I also put a shut-off valve in the deck pump-out hose adjacent to the macerator so it would never happen again.
 
svpilgrim said:
Most macerator pumps are self priming up to about 4 to 6 feet of vertical distance. As macerators age or become clogged with debris they loose the ability to self prime. .Typically the cutting blades / impeller on macerator pumps are serviceable & replaceable. Best to identify the brand and model you have then look up specs on line. You should be able to determine the macerator's original ability to self prime and if the unit is serviceable.

Ideally macerator pumps are located at the same level or below the base of the holding tank. Obviously this is not possible in M38x with the holding tank in the lower portion of the keel.

When I disassembled Pilgrim's (1979 M382 hull#115) original holding tank the discharge was a PVC pipe. The end of the pipe was slightly above the floor of the tank. Thus it would be impossible to empty the last inch or so of waste from the tank.

What are you defining as "the line"? Is this the run of hose between the macerator and the holding tank pick up? The run of hose between the macerator and the thru hull? Both? What makes you think you are clearing the line?

Are you certain the holding tank is not empty?
Click to expand...
svpilgrim said:
Most macerator pumps are self priming up to about 4 to 6 feet of vertical distance. As macerators age or become clogged with debris they loose the ability to self prime. .Typically the cutting blades / impeller on macerator pumps are serviceable & replaceable. Best to identify the brand and model you have then look up specs on line. You should be able to determine the macerator's original ability to self prime and if the unit is serviceable.

Ideally macerator pumps are located at the same level or below the base of the holding tank. Obviously this is not possible in M38x with the holding tank in the lower portion of the keel.

When I disassembled Pilgrim's (1979 M382 hull#115) original holding tank the discharge was a PVC pipe. The end of the pipe was slightly above the floor of the tank. Thus it would be impossible to empty the last inch or so of waste from the tank.

What are you defining as "the line"? Is this the run of hose between the macerator and the holding tank pick up? The run of hose between the macerator and the thru hull? Both? What makes you think you are clearing the line?

Are you certain the holding tank is not empty?
Click to expand...


Thanks for that.

You seem to have the best insight to my next question as you have disassembled the atmk.. I have removed the old macerator pump with more than the usual bloodshed. Before I install the new one I want to be sure I'm not just redoing what could be a bad install.
Firstly let me give you the lay of the land so to speak and make sure we are speaking in the same terms. The tank has 2 ports. One is the discharge side to the deck pumpout and I am confident that it goes to the bottom of the tank. The other is the inlet which comes from the head. The macerator currently is installed on the line that comes from the head to the inlet of the tank. There is T fitting in the tank inlet line, On the discharge side of the macerator it is tee'd into the sink drain. When you run the macerator you have to turn off the sink drain line under the sink or everything comes up through the drain, ugh!.
The big question and why I am suspect of this system, and if it ever worked is this. Does the inlet tube go to the bottom, or near the bottom of the holding tank, or is it "freefall" at the top of the tank. If it does not go to the bottom of course there is no way it will ever prime or empty the tank.
Normally macerators are installed on the tank discharge line, which will be a painful install on the 38, and I'll have to drill another hole in the boat, not a fan of that. I may just go with a deck pump and save a bunch of work.
Hope this is clear
 
Wolfe,

I'm not sure how much background you have on our modifications to SV Pilgrim. Soon after purchasing the vessel we became aware that the seal between the bilge and the holding tank was compromised. I am fairly certain the point of failure was the tabbing between the floor of the bilge and the vertical side of the keel. Rather than attempt to repair a design we felt was flawed, we chose install a prefab holding tank under the counter in the head and consolidate all the black water plumbing to the head. Here is a link to our photo album documenting the project... Holding Tank Install 2014

This left the original holding tank in the lower keel as an unused void. We choose to open the tank and inspect for damage, blisters, etc. After a very thorough cleaning we were able to ascertain there was no structural damage. We filled some cracks on the floor of the tank and then barrier coated the entire area. We then installed a series of three electric bilge pumps. Here is a link to our photo album documenting the project...Bilge Modifications 2014

From what we discovered in our bilge modifications the "inlet" tube extends a short distance, less than 3", into the holding tank.

Original holding tank inlet & pick-up

Original holding tank inlet & pick-up


Factory sealant used in holding tank plumbing

Factory sealant used in holding tank plumbing


I concur with your assessment. A macerator plumbed to the holding tank inlet would be practically useless.

If you are choosing to leave the holding tank in the lower bilge, then I recommend inserting a "T" or "Y" valve in the existing deck pump out hose. Install the macerator and dedicated thru-hull fitting in the starboard hanging locker opposite the galley sink.

Hope this is helpful. Please let me know if you have additional questions.

Jeff
 
Thanks for the clarification on the inlet configuration. Exactly as I suspected, a bad install. The macerator in the starboard cabinet is a consideration that we may look into going forward. In the interim I think we are going to go with a deck pump for emptying the holding tank. We use that system on our C&C 34 in Canada and though a little awkward is pretty foolproof, though tough to be discreet.
 
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