domestic water pump runs-on when tank is empty

[Xlantic]

When out of fresh water, my water pump just runs on. This can potentially lead to problems such as overheating the pump motor and breaking it or running down the batteries.

Is there a simple solution to this problem?

For example a timer that measures how long the pump has been running continuously that would trigger a buzzer or pump interrupt switch when a preset time is exceeded.

Ideas are welcome!

 

[bligh]

I run out of water about once a year and I cannot hear that pump running either. But when I leave the boat the water pump breaker goes off just in case anyways. Im sure that has occasionally saved an impellor.

 

[RT Firefly]

Greetings,
Mr. X. Tank gauge?

 

[catalinajack]

If my water runs out my pump will burn up within minutes. My solution? I watch my tank sight tubes. If you have no way of monitoring you water supply, install an in-line water meter assuming you know the capacity of your tanks. When I leave the boat, I turn off the pump in the event that a pipe breaks however unlikely that is.

When out of fresh water, my water pump just runs on. This can potentially lead to problems such as overheating the pump motor and breaking it or running down the batteries.

Is there a simple solution to this problem?

For example a timer that measures how long the pump has been running continuously that would trigger a buzzer or pump interrupt switch when a preset time is exceeded.

Ideas are welcome!

 

[GregBrannon]

Google found several 'water pump run dry protection' circuits, mostly DIY. I didn't find a ready device for sale that provided this protection, but I didn't look long. Most or all of the protection circuits require water level sensor in the supply tank, so you might as well install a human readable water level indicator and provide your own run dry protection. If running dry occurs when human intervention isn't possible, then I recommend securing the pump when not at the boat and then finding and fixing the water leak.

As others have indicated, what you describe is 'as designed' operation, and running out of water should be rare and anticipated. I've installed reliable tank monitors since owning my boat - it came with unreliable ones - but the boat's water system design reduces the chances that I'm surprised by empty water tanks. I have two large, self-balancing tanks that feed a smaller tank from which the house water is drawn. The two large tanks are completely visible with their water levels easily determined. Once the larger tanks are empty, I know we have 3-4 days of water with normal use until a refill is required, longer if we conserve.

Let us know how you resolve.

Greg.

 

[Westiculo]

You can put one of these in line.

https://www.supplyhouse.com/Square-...PSI-DPST-w-Manual-Switch-Low-Pressure-Cut-Off

 

[Larry M]

We added a pump on LED in the salon. When the pump runs, so does the green LED. It’s real obvious and has saved us a few times. The red LED is to indicate when the engine lights are on.

 

[High Wire]

For simplicity sake nothing beats monitoring tank level. It’s a daily check on my departure check list. Fill the tank at a level with one days (or more) reserve. Never challenge the pump. No different than your fuel tank.

 

[FF]

Problem solved https://www.supplyhouse.com/Square-D...essure-Cut-Off for $15.53 each.


NICE

 

[Xlantic]

Thanks for the insights.

I agree monitoring the water level is a good way to prevent the pump running dry and important in other ways. In my boat this is not impossible but somewhat inconvenient. I have a total of 7 fresh water tanks, the two aft ones under the bunks in the main cabin and the other five in the bilges. Only one, towards the middle, has a sight gauge but it takes an effort to read. By opening the valves in all the tanks the sight gauge will measure the combined level. I will change the current sight gauge tubing, somewhat yellow, to make it easier to read.

An indicator light at the helm would also help and is easy enough to rig.

Nonetheless, given the risk of running down, and ruining, expensive batteries, I would like a failsafe solution as well.

 

[Xlantic]

Googling "water pump run dry protection' I found this one which seems to be what I need but am not certain as the spec are not very detailed:

https://www.comet-pumpen.de/en/prod...n-pumps/accessories/pump-dry-run-control.html

 

[Xlantic]

The Square D device suggested by Westiculo and FF could be the answer but I don't know how it would be connected.

 

[ScottC]

Some interesting ideas have been mentioned.
I have installed a diaphragm pump, which doesn't seem to mind running dry.


Alternative & cheaper solution...wait for it... fill the water tank

 

[OldDan1943]

Greetings,
Mr. X. Tank gauge?

IMO, electronic read outs of tank levels are a 'suggestion.'

Sight glasses are better but, then generally do not read 'all the way to the bottom of the tank.'

If you run out of water, turn off the HW electrical heater. No need to burn out the heating elements.

 

[Irish Rambler]

Fit a diaphragm pump and a sight gauge to the instrument panel plus 1 in the galley. Simple, cheap and effective.

 

[BeeJay]

You could put a water level switch in line, the water pump is only live when water is present, the pressure switch will work as usual.

 

[High Wire]

A simple level column made of clear tubing could be tee’d into the pump suction line and run to a convenient spot. Water in the column will seek its own level same as the tank feeding the pump as long as the pump is not running. The top of the column must be open to atmosphere. This also assumes that the pump suction is off the bottom of the lowest tank.

 

[alormaria]

One of my PAR fresh water pumps has a red box attached to it's side that is connected to the pressure switch. It says it's an "Automatic Dry Tank Shutoff". The part number doesn't line up to anything by ITT or Jabsco. The instructions are to "Open line to water tank. Open one faucet. Press red reset switch and hold until water flows. Close faucet."



I've never had it in service but it seems to be designed to handle the situation.

The part number is 43003-0068 but that doesn't line up to anything like this device.

 

[Xlantic]

I have found this device but the price is $417

https://www.groco.net/products/pumps/accessories/noflo-dry-run-protection/noflo-7500

 

[FF]

Anywhere after the FW pump output the Square D could be installed.

Choose a spot that is easy to reach .IF the water pressure drops below 10psi the safety will turn off the water pump.

An accumulator will help if turning on the dishwasher, washing machine and starting a shower draws the pressure down.

These SQ D switches should be on every water pump as the pressure of/on can be owner adjusted . The switches on DC water pumps fail early , but the big sized contacts and wide opening allow these units to last and last.


For the $ its grand protection.

 

[Chrisjs]

The pressure cut-offs sound like a good idea. We had a similar problem with being unable to measure tank volume well because one tank was horizontal and low down. Our solution was to insert a domestic water meter (inexpensive) just before the pump. Knowing the combined tank volume at full, it was then easy to see water consumption and calculate water left in tanks.

 

[Xlantic]

Thank you for the inputs.

The Square D pressure sensor seems like robust, fail-safe solution and I will install one.

I will also improve my sight-glass and look into a flow-meter for more precision.

 

[Xlantic]

So, I bought and installed the pressure sensor with the low-pressure cut-off and it works as advertised!

As it turns out, my pump had a Square D pressure sensor (9013 FSG-2) so the switch to the one with the low-pressure cut-off (9013FSG2J24M4) was straight-forward.

The price I paid, though, was four times the one in the web-site suggested by Westiculo and FF:
https://www.supplyhouse.com/Square-...PSI-DPST-w-Manual-Switch-Low-Pressure-Cut-Off

For some reason that model is not readily available vía the Internet here in Europe and I bought mine in a local pump shop in Menorca, where I live, quite a small island in the Balearics.

I adjusted the cut-out pressure down to 30 psi (2 bars) which was the lowest I could get while still having the cut-off work when there was no pressure.

Thank-you all for the suggestions and now on to my other dozens of projects!

 

[STB]

Drop a water level switch near the bottom of the tank and wire inline with the pump, adding a bypass switch in parallel in case it fails. Or use one of the external sensors and associated control boards to do the same.

 

[C lectric]

Late but I will chime in.
I also use the Square D switch. One failed after 20 yrs. The contacts were ok but enough dirt got in that the mechanism failed. The switch will give you good service.
I replaced the failed switch a few years ago and carry a spare for the next time in about 15 yrs.

 

[cranger]

Water Pump

These are generally "demand" pumps meaning that they require water to fill their dead space before they stop running. First, when leaving my boat for any length of time, I simply turn off the water pump at the electrical panel. Second, if you're on-board and this happens, your faucet will start spitting air so just switch over to your next tank. Third, on my boat I can hear the pump running which may not be true for yours, but that signals me to switch to the next tank.