The Short Life of Four Water Pumps

[Big Nole]

Four freshwater pumps and one raw water pump [of unspecified brand or type or capacity] have burned out in two seasons.

I'm at my wits end with this problem.

I do not have a clue where to start [some unspecified process, perhaps means replacement of the unspecified brand or type or capacity of these pumps with ones that have a longer service life]

Please give me any recommendations [presumably for how to increase the service life of the pumps or what other brand or type or capacity of pump compared to the pumps that fail in two season would be better].

Replacing pumps is a costly option.

[Jefecinco]

I would suspect an electrical problem was/is causing the fresh water pump to run constantly. If your boat is operated in waters with a lot of marine growth some may have been sucked into the pumps causing early failure.

Q1: are your pump intakes protected by a a strainer?

[jimh]

As Butch alludes, a very reasonable basis to assume as the cause of a very short service life of an electrically-operated pump is for the pump to be run at a much higher duty-cycle that anticipated by the manufacturer of the pump. Another very reasonable basis to assume has caused a failure in the pump is it is continually being run without any water being pumped.

The typical plastic centrifugal-type lifting pump is not rated for continuous duty. They are expected to only run very sporadically, and when running to only run for a minute or two.

A very easy way for a lifting pump that is intended to remove water from a sump area and is being controlled by a float switch to be able to run continuously is for the design of the control system to be extraordinarily badly designed. For example, for a pump controlled by a float switch to work properly, once the water level in the sump area rises high enough to cause the float switch to switch to RUN mode, the pump MUST be able to remove enough water from the sump to get the water level low enough for the float switch to revert to OFF mode. In order for that to happen, the float switch must be carefully located in relation to the water level in the sump that is the level that occurs when the lift pump stops being able to lift water. You might think this was endemic in any boat design, but maybe not always.

If the boat has a leak and water is continually collecting in a sump area and the float switch is continually asking for the pump to run, and even if the float switch is properly located so the pump shuts off, the continual leak of water into the sump is going to--you guessed it--continually keep the pump coming on to remove the water.

In water lift pumps some designs rely on there always being water in the pump when the pump is running as a way of handling the heat generated by the work being done by the electric motor. Your use of the phrase "burn out" may be very cogent if the cause of these seemingly premature pump failures is due to lack of water in the pump when running. Also many pumps use a rubber impeller to move the water, and if there is no water to lubricate the rubber vanes of the pump as they rotate against a steel enclosing chamber, the rubber will rapidly heat, and eventually deform.

Also, when soliciting advice, your solicitation should make very clear exactly what advice is being sought. When describing an unanticipated failure of a component, give more details about the component and its brand, type, and particulars.

[jimh]

Some other ways to increase the service life of water pumps:

• buy higher quality pumps rated for a higher duty cycle;
• by pumps with higher flow rate capacities, as this will reduce the amount of time they will need to run to evacuate the undesired water;
• by pumps with with diaphragm action that can be moved out of the area where water accumulated and located in a dry area, and still be able to lift water and prime themselves.

Pump Nomenclature

The vertical distances related to a lifting pump are characterized by two metrics, LIFT and HEAD.

A pump's lift capability is the vertical distance that the pump can pull up a liquid that is below the pump's centerline into the pump's input.

A pump's head capability is the vertical distance the pump can raise the liquid in the exhaust port path.

The typical centrifugal plastic pump is designed to be immersed in the sump water because it has essentially zero lift capability. The flow rate of a centrifugal pump will significantly decrease as the head on the pump increases.

A diaphragm pump will have significant head capability, often several feet. A diaphragm pump will also tend to produce a steadier flow rate even as the head on the pump increases toward the maximum.

The head on the pump is related to the volume of water in the output path, so essentially its the weight of water that must be pushed out.

The advantage of a plastic submersible centrifugal pump is a relative low cost; other than that everything else is at a disadvantage compared to a diaphragm pump.

The disadvantage of a diaphragm pump is its cost, which is probably four or five times the cost of a centrifugal pump. Otherwise everything about the pump is an advantage compared to diaphragm pump, including the ability to pass small debris right though the pump without harm.

ASIDE: many years ago, c.1988, I installed a Jabasco 36600 Diaphragm Bilge Pump (which as I recall cost about $150 then) to remove water from the deep keel sump of a 30-foot sailboat. The pump was located below the cockpit deck in a machinery area, and it would lift water about six feet vertically from the keep sump to its input and literally throw the exhaust water five feet astern via an above-the-water-line port on the transom. I would bet that pump is still working today. Replacement diaphragm kits were available back then as that was about the only wear part other than the electric motor. Alas I see it has been discontinued, probably because the price rose to maybe $500 or more.

https://www.xylem.com/en-us/products--services/pumps-packaged-pump-systems/packaged-solutions/drainage-dewatering2/36600-diaphragm-bilge-pump/

[Big Nole]

I would suspect an electrical problem was/is causing the fresh water pump to run constantly. If your boat is operated in waters with a lot of marine growth some may have been sucked into the pumps causing early failure. Are your pump intakes protected by a a strainer?

The strainers were/are clean. The pump does not constantly run, I can hear it when it does. These are not cheapo pumps with low gpm, most were 5 gpm. I thought clogs may have done it but nothing. I know [the cause of the unexpectedly short service life of the pumps] must be electrical [in nature], but [to know] where to start [the remedy] is [my] problem.

[Big Nole]

The freshwater and raw-water pumps that have all failed are listed below [with their brand and specifications]:

FEITON 6.5-GPM 70-PSI 12-VDC RV Fresh Water Pump Self-Priming Diaphragm Pump

SEAFLO Water Diaphragm Self Priming Pump 3-GPM (10.6 LPM), 45-PSI, New, RV/Marine, 12-Volt DC, 12-Volt Demand Fresh

YOUNGTREE RV Fresh Water Pump 12-Volt 5-GPM 55-PSI, 12-Volt DC, Self-Priming Water Pump

Johnson Pumps Model 10-13329-103 Aqua Jet FlowMSTR Pump 5 GPM, 12-Volt

Circle River 3.5-GPM 55- PSI RV Fresh Water Pump, RV, 12-Volt, Premium, Self-Priming, Diaphragm, RV, Water Pump 42-Series

These pumps do not run continuously.

[jimh]

I know [the cause of the unexpectedly short service life of the pumps] must be electrical [in nature]...

Your surmise that the cause of the failure of the pumps to work MUST be due to an electrical problem, rather than a mechanical problem like a failure in the actual mechanism of the pump, is very interesting. Your comment provokes this new question:

Q2: when a failed electrically-operated pump is replaced by a new pump of the same type and the new pump is connected to the same electrical circuit as the failed pump was connected, does the new pump operate?

Also, for all of those pumps to fail and for the cause of the failure to be electrical, then the source of electrical power for all those pumps would need to be a common source.

Q3: were all of the pumps that failed being powered by the same power source?

[Big Nole]

Q2: when a failed electrically-operated pump is replaced by a new pump of the same type and the new pump is connected to the same electrical circuit as the failed pump was connected, does the new pump operate?

When I replace the burned out (non-operating) pump with a new one, the new pump works fine but only for a couple of days or so then completely stops.

Q3: were all of the pumps that failed being powered by the same power source?

[The pumps that have failed] have all been using the same power source: a battery.


I agree that [the cause of the repeated failure of multiple water pumps] must be [due to] electrical problems.

Q4: how are electrical problems diagnosed?

Q5: how are electrical problems remedied?

Thanks.

[jimh]

Is there any chance you are running 12-Volt pumps on 24-Volts?

[Big Nole]

Is there any chance you are running 12-Volt pumps on 24-Volts?

[There is] no [chance the pumps are being run on 24-Volts]. [The pumps] are run off of 12-Volt batteries.

[Big Nole]

Update, I went to the boat [on August 29, 2024] and the pump was working.

I am now really confused.

I did check the filter and it was fine.

[jimh]

Q4: how are electrical problems diagnosed?

Electrical problems are generally diagnosed by analysis of the electrical circuits involved. The voltage and current at various points in an electrical circuit are measured. The measured values of voltage and current are then compared to the expected values that should exist at the measurement points. If a measured value deviates from the expected value, the circuit is then analyzed to see what failure or fault in the circuit could produce the discrepancy between the expected value and the measured value.

In order to use this method, the fault condition must exist. The expected values must be specified in the circuit diagram or deduced by analysis of the circuit by the diagnostician, who has thorough understanding of electrical circuitry or the normal values have been measured previously when the fault was not present.

I know this is a general answer, but since you question was totally unspecific to any particular circuit and no details have been provided about a circuit, about the only answer that can be provided is a general answer.

[jimh]

Q5: how are electrical problems remedied?

Once the cause of a problem in an electrical circuit has been identified as due to a specific circuit element being at fault, the faulty circuit element is replaced with a nee component of the same specifications, including the electrical value of the circuit element being replaced and perhaps with an increase the quality or durability or expected service life of the component so as to reduce the chance or a repeat failure in the future.

I know this is a general answer, but since you question was totally unspecific to any particular circuit and no details of the circuit have been provided, about the only answer that can be provided is a general answer.

[jimh]

Is there any chance you are running 12-Volt pumps on 24-Volts?

[There is] no [chance the pumps are being run on 24-Volts]. [The pumps] are run off of 12-Volt batteries.

The fact that there are 12-Volt batteries in the plural suggests that due to a wiring error it is possible that a load connected to two 12-Volt batteries could be operating at 24-Volts if there were an error in how the 12-Volt loads were wired to the two 12-Volt batteries.