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drblogan · 19-04-2010, 07:58

Maggie and I live aboard a Manta42 catamaran, built in Sarasota in 2008. We have a Village Marine [Little Wonder 300] the feeder motor of which gets extremely hot and shuts down after 20 minutes use. Raw water inflow, via the seacock, is excellent; pressure at the 5 micron filter is 24-27; membrane pressure is at 800 and the product flow is 12G/hr. I do not understand why the feeder pump gets so hot. The pump is a Flojet continuous flow type, which delivers 3.3G/min. Any ideas?

TaoJones · 19-04-2010, 08:49

Welcome aboard, drblogan! We're glad to have you here.

You will notice that your post has been moved to the Plumbing Systems and Fixtures Forum, since you have some specific questions regarding your watermaker. I'm guessing that there is some resistance introduced into your system at some point that is causing the pump to have to "push" too hard, overheating in the process. Hopefully, one of the members who is familiar with your particular Make and Model will have some more specific advice for you.

Again, welcome to Cruisers Forum.

TaoJones

Watercolor · 25-04-2010, 18:27

Just a couple thoughts. I'm no expert at watermakers. In addition to Taojones back pressure comment, the only other possibility (barring a defective pump, would be lack of cooling source(air).

How long have you had the watermaker? Has it always done this or is it a new phenomenon? If it's something new I'd check the 5 micron filter.

If you're getting the proper flow rate in the first ten minutes from the system now, my guess is that the membrane is working properly.

You might try disconnecting the input line at the watermaker and then doing the test with the filter in place and removed.

Next I'd check to see if the pressure relief valve is working properly`. There should be a pressure relief valve, shutoff and gage on the low pressure overboard line from the membrane housing. If the excess water and brine go to a below water seacock, the seacock could be blocked or closed.

Best of luck and fair winds,

Jed

Watercolor · 25-04-2010, 19:01

Since I don't know where you are and therefore the cost of shipping, I'll sell the two components for $240.00 and you pay COD and shipping by what ever method you chose.

I don't have a Paypal so the $10.00 covers basically the COD charge. I have no idea what charges PayPal has.

I've sold many items on the Forum this way in the last year, only one was sent COD.

What I've done in the past is, on receipt of the check, I send the item out immediately, usually Parcel Past priority.

Again, Fair winds,

Jed

drblogan · 26-04-2010, 01:26

Thank you for your observations on my Little Wonder 300 [LWM300] water maker. The LWM300 was first used October 2008. It worked fine until February 2009, when the seacock disintegrated. I had to wait until July to get a replacement. All well until September 2009, when the Flojet feeder pump [3.3G/min] failed. I replaced it with a Flojet [3.3G/min]; but, it was a shower pump, not appreciating that it needed to be a continuous flow pump. A month later, with the LWM300 producing 8G/hr, instead of 12, a Spectra engineer, in Grenada, discovered that a fuse, in-line to the Flojet, had blown. All well, until March 2010, when the circuit breaker to the LWM300 tripped. From then on, the Flojet worked for 20 minutes, before shutting down, due to over-heating. One of two electric motors, which drive the HP pump, burnt out; the brushes on the other motor had all but disappeared! Now, with the correct spec continuous flow Flojet, a new electric motor and re-newed brushes in the other, the Flojet shuts down after 30 minutes. I have applied a fan over the Flojet; with that, the Flojet runs continuously. A new membrane produces 12G/hr as specified in the manual.
Bernard

drblogan · 26-04-2010, 01:36

Thank you, Taojones, for your welcome and advice. My concern with the concept of back-pressure is that the pressure at the exit point of the 5 micron filter is well within the recommended level of 35lb/sq". If there is back-pressure, would the observed pressure not be greater than 35lb/sq"? There is no kink in any of the lines and reject water is exiting, above sea water level, at as good a rate as I have seen. I should mention that raw sea water is directed to the Flojet continuous mode pump [3.3G/min]; from there, the water enters an air/oil separator and, then, to a 5 micron filter. A pressure guage is at the exit point of the 5 micron filter; next stop: HP pump.
Bernard

Minggat · 26-04-2010, 01:56

Are there wires in the feed pump circut that also get hot? Sounds like it's starving for power to me.

drblogan · 26-04-2010, 02:09

Haven't felt the wires. However, there are interesting findings: The Flojet feeder pump [continuous mode producing 3.3G/min] is supposed to take a maximum 6A load. With the generator [5.5kW] supporting the battery bank, current flow to the Flojet reaches 7A; but, the return flow down the neutral wire is at 6A! There is, also, a voltage of 0.5v between the Flojet casing and the neutral wire. With the generator off, but support from 6 solar panels and a wind turbine, the current flow to the Flojet still exceeds 6A.

**Tellie** · 26-04-2010, 17:52

I'm a little confused. You say there is a .5v difference on the neutral wire? Is this a 12v unit or a 110v unit?

drblogan · 27-04-2010, 04:08

12v. The voltage drop occurs between the Flojet casing and the neutral wire from the Flojet

**Tellie** · 27-04-2010, 05:17

Quote:

Originally Posted by drblogan

12v. The voltage drop occurs between the Flojet casing and the neutral wire from the Flojet

The reason I asked is 12v pumps have a positive and negative wire. 110v have a neutral wire. I suspect you mean the black negative wire. What size are the red and black feed wires and how long is the run from the pump to the power source? Flo jets have thermal overload protection. If it is shutting down because of heat it is doing what it supposed to do. Why you are creating such heat is the problem. Electrical problems are tough to fix without being there. My first thoughts are bad wire, bad/corroded connections or improper voltages, perhaps the wrong pump. Take voltage readings at the breaker and at the motor. Also what are the model numbers on the pump motor?

drblogan · 27-04-2010, 11:50

I believe the feed wires are 12gauge; they are same as those from the Flojet. The Flojet was provided by Village Marine; it is not available in the various chandelers in the Caribbean. I believe Flojet make the pumps for Village Marine. The feed wires are just two years old and the connections have, recently, been cleaned. Voltage readings with my 5.5kW generator backing up the battery bank:
Circuit Breaker: 13.2v Motor: 12.78
After 35 minutes, the voltages were:
Circuit Breaker: 13.75 Motor: 13.00
Current down the feeder live wire 7A
Current down the negative wire 6A
Voltage drop between the Flojet casing and the negative wire: 0.53v
With the generator off and the battery bank boosted with six solar panels and a wind turbine:
Circuit Breaker 12.60v Motor 12.2v Current Live 6.3A Current Neutral 5.3A
Voltage drop between Flojet casing and Neutral: 0.46v
Flojet continuous mode pump: Model 4105-501 S/N 05044884
Current flow is supposed to be a maximum of 6A
Finally: Current to the left-hand electric motor is at 3A; that to the right-hand electric motor is at 20.5A Both motors sit astride the HP pump; their drive belts drive the same wheel, which is attached to the drive shaft of the HP pump.

**Tellie** · 27-04-2010, 13:46

Does it say continous flow somewhere on the pump? I thought 4105-501 pumps were Intermittent Duty pumps. I'd double check with VM on this. If they are 15-30min ID pumps then I'd say the problems you describe would make sense. Also the pumps wires are 18AWG.