Head Pump Booster

[Derik]

I just rebuilt my aft marine head, with a Jabsco kit. It works but not any better than it did previously but it is no longer leaking.

The freshwater tank it draws water from is too far down in the boat so it's pumping up about 3 ft. Pump pressure is low and it takes too long to get water in the head. I can't imagine it would ever fill the head enough to go number 2.

Has anyone ever put a booster pump in-line before the toilet pump? Seems pretty easy and I could easily wire it to the head switch to come on when I depress the head switch.

 

[kthoennes]

Boy, makes me think that there's something else going on besides the pump. Kinked or restricted supply line maybe? One of our heads is close to the supply tank, but the other is a mile away and flows fine. A new Jabsco pump should have no problem with a three foot lift. Our macerator pump loop has a three foot lift from the holding tank to the top of the loop then back down to the thru hull and flows easily. Different model pump I know, but same pump mechanism as I recall.

 

[JustCruisin]

I have the same issue...Jabsco 37010-1090. Mine draws raw water and if I hook it to a pail next to the head it does well but doesn't seem to be able to lift water from the thru hull very well. Have verified that the supply hose and thru hull are clear. New impeller made no real difference. Maybe it's all it can do...I can live with it but wish it did better.

 

[Derik]

I too tried pumping from a 16 inch length of hose from a bucket worked great. I am going to replace the old line to the freshwater head tank and if that doesn't work use a booster.

 

[Bmarler]

If you do install a booster pump I’d suggest powering it through a relay so you don’t overamp your existing switch. Unless, of course, you know your switch is capable of the load.

 

[STB]

Hi all,

I'm not sure how much head you've got, but I think the 37010 series can support a head of up to 4' for each of flush and discharge. Please check the manual for whatever unit you might have or post the model here and I can try to find it.

If you are pumping against more than 4' of head, I see the problem, but I think 3' of head was reported here.

So, I see a couple of possibilities:

1) It is more than 4' of head
2) The electrical supply is compromised by corrosion of the connectors, connections, and/or wires, and the pump is seeing too little voltage and, even drawing more current, isn't able to do as much work.
3) The water supply path is heavily constricted
4) The pump is worn out and leaking internally, unable to develop enough pressure.

I would have guessed another possibility, that expectations weren't appropriate, but the owner reported being satisfied while it was pumping from less distance

My first guess on these types of things where electrical wasn't checked early in the process is always electrical. Electrical maintenance tends to get neglected in general, and especially near the head.

If everything looks good try checking voltage at the toilet while flushing. And, if your meter supports the current level and has a hall effect (DC) current probe. I'd suggest checking with an in-line DC ammeter that supports the current level, but sometimes folks have trouble getting good connections in situations like this, so I recommend that only if you feel confident you can get a good test.

 

[OldDan1943]

Check the discharge of the pump by pulling off the hose.

I agree with the suggestion, trace out the water line, looking for kinks and tight bends and turns etc.

 

[jungpeter]

I just rebuilt my aft marine head, with a Jabsco kit. It works but not any better than it did previously but it is no longer leaking.

The freshwater tank it draws water from is too far down in the boat so it's pumping up about 3 ft. Pump pressure is low and it takes too long to get water in the head. I can't imagine it would ever fill the head enough to go number 2.

Has anyone ever put a booster pump in-line before the toilet pump? Seems pretty easy and I could easily wire it to the head switch to come on when I depress the head switch.

Hi Derik. If yours is truly a head designed for fresh water use, it likely uses pressurized fresh water from your potable water system to fill and flush. AND, it should have a solenoid valve on this line (normally closed, and only energized by the "ON" button to the head) to prevent backflow into your potable system from the head. If you're relying on the head itself to provide flow from a non-pressurized source, then nope, it's not designed for that, and unlikely to function properly, unless that fresh water source is located on or above the level of the head itself. And however you lash this thing up, don't forget to isolate it from your potable water source. E. coli is nasty stuff.

Regards,

Pete

 

[STB]

To Peter's point, if it is something along the lines of the Jabsco 37245 series freshwater toilet the original poster reported, vs the 37010 series a subsequent poser reported, it takes a flow rate of 3.5gpm at the toilet. So, you might consider the capabilities of your freshwater pump. It might be undersized for the purpose, especially if it is marginal and fighting a lot of head pressure. An upgrade there might be helpful.

 

[HeadMistress]

A Jabsco 37010 is a sea water toilet that can lift up to 4..it does not need, nor should it use pressurized flush water. Put an amp meter on it WHILE FLUSHING...if it's not getting 12v, the battery may be weak or the or wiring could be the wrong size. However, you said the toilet pulled water out of a bucket just fine, so I think we can rule out the battery or wiring.


Something just hit me: we've talked about the toilet's ability to LIFT 4' max, which would be PUSHING IT UP from the toilet to a tank above it...he's trying to PULL water up to the toilet. I've never seen a spec saying how high the 37010 pump can pull water. So I suggest you ask Jabsco tech support. Paul Campagna is Jabsco's toilet guru...his direct line is 978.282.5246. He'll be able to tell you whether the solution is a "booster" pump or maybe just raise the flush tank foot if possible.


--Peggie

 

[STB]

I've never seen a spec saying how high the 37010 pump can pull water.

Hey Peggy, In my copy of the 37010 manual it lists both pulling seawater and pushing discharge separately, but each as 4'. See attached.

 

[Derik]

My head is an older non freshwater design 37010 jabsco that the previous owner made into a freshwater head. He added a 40 gallon isolated tank in the bottom of the boat it is isolated from my 300 gallon freshwater tank that I use for everything else.

Toilet works great if you add water to it manually but doesn't fill quickly and long pump run times are necessary.

I'll check electrical but like I said the flush part works great which I believe takes more power than the pump part.

 

[HopCar]

The toilet should work when mounted up to 4 feet above the water source.
Is your water level in the tank more than four feet below the pump? Fill the tank.
Are all the connections on the supply line tight? A small air leak would cause this.
Is the tank vent clear? Air has to get in for water to get out.
Is the supply line between the pick up and pump restricted anywhere?
Is the impeller worn?
Is the pump body worn?
Is the wear plate worn?
Did the paper gasket get damaged during assembly?

My bet would be a partial blockage on the tank vent, but that’s just a wild ass guess.

 

[Rufus]

I'd opt for an appropriately sized diaphragm style lift pump and get rid of the noise-maker impellor intake pump(s) on the head(s). Make sure the intake hose is sized correctly. Wire an extra switch to add water in the bowl (without flushing) as an extra feature.

 

[HeadMistress]

Intake and flush water limits in that piece both tell you how high the toilet can PUSH water...you're just trying to PULL water up the bowl. I suggest you ask Jabsco tech support. Paul Campagna is Jabsco's toilet guru...his direct line is 978.282.5246 I also recommend that you have an accurate measurement of the actual distance between the toilet intake fitting and and the flush water discharge fitting before you call him.


--Peggie

 

[HopCar]

Peggy, Jabsco makes several small pumps that use that same impeller. They will all self prime to at least four feet. Maybe the water level in the tank is below four feet.

 

[STB]

Intake and flush water limits in that piece both tell you how high the toilet can PUSH water...you're just trying to PULL water up the bowl.

The pump is integrated into the toilet as opposed to external along the path or at the tank. It can't push water from the tank. It /necessarily/ pulls it: By intention, by design, by construction, and by configuration in this application.

We aren't talking about a situation where any component of the toilets water supply is above the toilet -- and if the supply itself were above the toilet the water would be lowered, not lifted, and gravity would help.


The "push" is a tiny and fixed distance from the pump's location in the base of the toilet to the discharge at the top of the bowl.

The posted manual is quite clear about the pump's intended capabilities in this respect, I think, "Flush pump is self-priming with a vertical lift up to 4 feet;".

Of course, "up to" means in ideal practical circumstances. Too much constriction (supply, discharge, or vent), too much friction (supply, discharge, or vent), too little voltage, dirty or worn or obstructed or broken pump components, etc, etc, etc can limit that.

The questions in this case are, I think, if the pump is behaving less than ideally, what are the contributing factors? And, what can be done about them?

This is a different situation than the freshwater pump where the manual states a minimum flow rate at the device for proper function rather than an integral capability.

 

[Mac2]

I just fixed a similar low pressure situation on my raritan. When I unhooked the freshwater line at the toilet, I accidentally found a filter inside the line just before the solenoid. It was caked on with gunk. Surprised water could get through. It has a raised tab in the center that is designed to be grabbed with needle nose pliers. I cleaned it and my toilet is like brand new. I thought about removing it but was talked out of it because it could flood the boat if a piece of grit holds the solenoid open. Also noted is that I have a mesh strainer before the house pump. It took three years of livaboard to clog the filter.

 

[HeadMistress]

Peggy, Jabsco makes several small pumps that use that same impeller. They will all self prime to at least four feet. Maybe the water level in the tank is below four feet.

Parks, the toilet has to pull from the discharge fitting on the tank, which is at the bottom of it, so I don't THINK the water level in the tank has anything to do with it. I'm becoming more and more convinced that the lift is higher than the toilet can do. But to repeat, it has to PULL water up to the toilet and I don't know how that correlates to how high the toilet can PUSH it...which is the reason I recommended he ask Jabsco's toilet guru.


--Peggie

 

[STB]

But to repeat, it has to PULL water up to the toilet and I don't know how that correlates to how high the toilet can PUSH it...which is the reason I recommended he ask Jabsco's toilet guru.

Peggy, what is being pushed?

The discharge is being pushed, but thats not what we are talking about. The water is being pushed from the base of thebtoilet to the rim, but that is a factory-fixed small number of inches.

The spec for the saltwater toilet is to self-prime and pull water: up to 4'. The spec for the freshwater toilet is for the freshwater systems pressure pump to push the water into the toilet with a flownrate if not less than 3.5gpm. The freshwater pump is doing the pushing, not the toilet.

In the case of the person having the trouble with the freshwater loop, my first check would be to see what the rating is of my freshwater pump for the amount of lift. It coukd be that the freshwater pump needs replaced. I'd add a better freshwater pump before adding a lift pump. It has the benefit of providing better showers and sink function -- and I'll bet that sink is higher up. If the higher up sink is fine, I'd be looking for a constriction related to the toilet, starting with the solenoids that control freshwater flow and the electricity to them. I still suspect an electrical problem as there are no complaints about the shower or sink -- powered by the same freshwater pump. But, it could be a tank vent or other global issue and the user is just more tolerant of slow flow w.r.t. other devices.

In the case of the person with the saltwater toilet, even when employed pulling water from a special freshwater tank, now I am concerned about lifting the water from the ocean or the tank into the bowl. There is still no pushing. The spec here is 4'. If the lift is outside of that spec, or close to it, a boost pump may make sense. But, if not, I'd rather find and fix the problem than add complexity to patch around it. I'd want to know why the pump isnt able to do its job. Corroded electrical? Constricted hoses from delamination or crud? A bad bend? Etc.

The only fluidbbeing significantly pushed is the discharge. And that is 100% not the concern here (And the spec for that is given).

 

[HeadMistress]

The spec for the saltwater toilet is to self-prime and pull water: up to 4'. The spec for the freshwater toilet is for the freshwater systems pressure pump to push the water into the toilet with a flownrate if not less than 3.5gpm. The freshwater pump is doing the pushing, not the toilet.


This issue has nothing to do with how high the toilet can LIFT (push), it's about how high it can PULL. You just cleared up for me that it's the same for both: a max of 4'...and that's only if it's a straight run.



The toilet has to pull from the discharge fitting on the flush water tank, which is at he bottom of it, so you have to measure the the height/distance from there to determine whether it exceeds 4'. If it does, then yes...a booster pump be needed unless you can raise the tank.


However...it would pushing while the toilet is pulling, which means they'd have to work in sync...and that's one of the reasons I think you should have a talk with Jabsco's toilet guru. He should be able to recommend a pump or may have anoher solution.


--Peggie

 

[SteveK]

Is the fresh water tank just for the head?
If not and is also the domestic supply then would tapping into the onboard pressure system, like we do with marine elegance solve the problem.

 

[HopCar]

Parks, the toilet has to pull from the discharge fitting on the tank, which is at the bottom of it, so I don't THINK the water level in the tank has anything to do with it. I'm becoming more and more convinced that the lift is higher than the toilet can do. But to repeat, it has to PULL water up to the toilet and I don't know how that correlates to how high the toilet can PUSH it...which is the reason I recommended he ask Jabsco's toilet guru.


--Peggie

Peggy the pump only has to suck water from the water level in the pickup tube which will always be the same level as the water in the tank. It doesn’t matter how long the pick up tube is.

This assumes that the impeller is wet or greased. A completely dry impeller doesn’t seal to the pump housing as well as a wet impeller. A completely dry impeller will only self prime to about half the height of a wet impeller.

It certainly wouldn’t hurt for him to talk to your guy at Jabsco.

 

[STB]

In the case of the freshwater unit, the toilet doesn't have to suck water from the freshwater tank at all. It is pushed in at a flow rate of at least 3.5gpm by the boat's freshwater supply pump, provided that pump meets spec for this application. It doesn't matter how high it is as long as there is 3.5gpm at the toilet.

In the case of a saltwater flush toilet plumbed normally, the vertical distance between the waterline at the hull and the pump in the base of the toilet (*) needs to be 4' or less under the best of real world conditions.

In the case of the saltwater flush toilet being plumbed atypical to draw from a special freshwater tank, the toilet will be able to, under the best of real wprld conditions, pump to spec from that tank so long as the actual water level in that tank is less than 4' below the pump in the base of the toilet (*). A tape measure can answer this question, I suspect.

Unless a substantial portion of that saltwater toilets freshwater in the special tank is more than 4' below the pump in the base of the toilet, I don't think that's the problem. If it were, I would expect the toilet works well from a full supply tank but have trouble as that tank approaches the last X%.

...I am curious if this "special tank" has a proper vent, or at least a truly functional one. If not....that'll make things hard to implosion.

Just in case there is any confusion, the depth of the pickup tube in the tank does not matter. Nor does the location of the thru hull, soclong as it is submerged. Put a straw into a glass of water and the water level in the straw will quickly align with the water level in the glass. The pump doesn't need to achieve that movement.


(*) My read of the spec is that the pump can discharge into the bowl at a sufficient rate of flow so long as the pump itself is 4' or less from the water level within the vessel from which it is pumping (ocean, special tank). If someone wants to argue that the spec should be read to mean 4' from the rim of the bowl where the water is discharged, that isn't my read. But I do understand it.

 

[HeadMistress]

Peggy the pump only has to suck water from the water level in the pickup tube which will always be the same level as the water in the tank. It doesn’t matter how long the pick up tube is.
It certainly wouldn’t hurt for him to talk to your guy at Jabsco.

What pickup tube, Parks...what am I missing? The toilet's flush water line is connected to the flush water tank, which is below the toilet, so it has to pull water of the tank which typically has a discharge fitting at the bottom. Some water may rise in the toilet intake line, but the toilet still has keep pulling water out of the tank, which brings us back to how high the toilet can pull it.

Where's the flaw in that scenario?

And it just occurred me that there's a question I don't think we've ever asked: how big is the tank? How tall is it?

--Peggie

 

[STB]

Hi Peggy,

Correct....how high the toilet can pull it...and the spec says that it should be able to pull it 4' above the waterline in the vessel from which it is pulling it.

It doesn't matter if it is drawing it from the top, the bottom, or anywhere in between for the same reason that if I put a straw in a glass and pour water into the glass, even though the opening in the straw is at the bottom of the glass, the waterline in the straw will rise to match the water level in the rest of the glass.
(Feel free to try at home...we can talk about surface tension and capillary action, etc, later).

The pressure in a vented water column is linearly related to the depth of the column. The vented tank is one column. The hose leading to the pump is another vented column. They are connected such that water can flow in between. The pressure pushing down on the vented tank will push water up the hose until the water level in each is the same, because until they are the same there is a pressure differential motivating leveling. This is what people mean when they express that, 'Water seeks its own level". The pump doesn't need to move the water in the hose up to the level of the water in the tank -- the water does this itself.

Describe it as pushing, pulling, pumping, lifting, or twerking, the pump spec says, in an otherwise good situation, the toilet's own pump is good for 4' from the water level in a properly vented tank.

 

[kthoennes]

I don't mean to drift this thread into mechanical metaphysics, and far be it from me to second guess Peggy, but doesn't every pump by its nature and design push and pull? Seems to me every pump has a discharge side (push) and intake side (pull). I don't get this discussion. All I know is that I have five jabsco pumps on my boat and they all push and pull just fine, including the macerator that has to suck water - and stuff - just over three feet up, chop it to bits, and then push it four feet down and out the thru hull.

 

[STB]

Hey Kthoennes,

I think there is a lot being conflated and confused in this discussion, and that none of it matters, anyway, so I am reluctant to make it worse with technical details that don't matter, but let me offer a quick example of what people usually mean when they express that a pump is pushing or pulling.

Let's imagine that I put a pump right darn in a fuel tank and it's job is to move fuel up through a hose to the engine. This pump is said to be pushing the fuel. This is because the side of the pump restricted by the hose is on the discharge side and has positive pressure (it wants to leak outward if it gets a hole)

Now let's imagine that we move that pump all the way up to the engine that it is servicing. The side of the pump restricted by the hose is on the suction side and has negative pressure (it would want to suck air from the housing in if it got a hole.). This pump is said to be pulling.

A pump positioned in the middle of the line can be said to be pushing and pulling. Put it closer to one side than the other and it'll be doing one more than the other.

Different pump designs react differently to the difference in configuration, especially when priming.

None of this matters here. Because Jabsco tells us that it can self-prime and lift water up to 4', we don't need to be concerned about any of this. They've given the answer. Quite clearly.

The pump is integrated into the toilet vs in the tank or somewhere along the way, so it is pulling in all cases. There is no chance they meant 4' only in a push configuration, because that configuration is simply impossible in this application.

In some other world where we were designing the system we might find that a pump could work well enough if we were to locate it at the tank, but couldn't prime if we located it at the toilet, so it we would need to prime the system. We might also, possibly, find that a pump doesn't do well with a huge pressure we difference, so it is better sitting right in a tank than in line. But none of that is this situation.

The best I can offer you as a familiar example is an AC pump. Ever had one above the water line? They work great once you prime them. But, if you don't do that, no bueno. Those pumps can pump water against substantial head -- but can't prime in that situation. This stuation with the toilet isn't that.

If you want, you can probably google positive displacement pumps (PDP) vs non-positive displacement pumps (NPDP), i.e. "PDP vs NPDP pumps" for some more details.

I guess I'll also add that a pump that is pulling has a theoretical limit because, at best, it can generate a vacuum. Then there is nothing more to suck out. It is actually the atmosphere doing the pushing to move the fluid. A push pump can shove as many molecules around as it can grab, so it doesn't have this limit. But, again, this is super far removed from this discussion which describes the movement of water in a way no different, really, than the way we all move water from the freshwater tank to the lav or shower, other than it ends with Whoooosh!

The whole pushing vs pulling thing is really most often either about priming or about selecting an appropriate pump design.

 

[Derik]

I replaced the supply line. It had a substantial kink in it. Flow improved but it was rather short lived. The 3/4 inch supply hose I used was from home depot a reinforced braided vinyl hose. It soon collapsed to a point where the flow was somewhat restricted again. Better and the toilet doesn't leak but I need to get a maybe a washer style hose?

 

[STB]

I replaced the supply line. It had a substantial kink in it. Flow improved but it was rather short lived. The 3/4 inch supply hose I used was from home depot a reinforced braided vinyl hose. It soon collapsed to a point where the flow was somewhat restricted again. Better and the toilet doesn't leak but I need to get a maybe a washer style hose?

Where in the world are you located? In the US, I'd send you to West Marine for a hose.

But, can you help me understand what you think caused the collapse? Is it a tight bend?

Is this the installation with the true freshwater toilet? Or the one using a saltwater toilet drawing from a tank?

If you think suction collapsed the hose I'd like to understand the source of the suction, i.e. saltwater toilet vs freshwater toilet and if there may be any obstructions.

I'd also like to make sure anything drawing from overboard via a thru hull is up to that task for safety reasons.

Any chance you can remind us of your configuration and, if itncollapsing from a bend ornpositioning, maybe post a picture of where it is collapsed so we can see the situation.

Thanks!