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Old 08-04-2018, 08:31   #1
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Bilge Pump Continiouslly switches On & Off.

I have a Rule Mate 1100 gph bilge pump in each of my bilges in my catamaran. The alarm activates in my saloon at the nav station. It drives my crew and I crazy. I can switch the alarm buzzer off but dont wish to do so. My crew do so when Im not looking. It continiouslly switches on and off at regular intervals. It seems that the little bit of water sloshes around in the bilge activating the float sensor switch. Should I use a different / better pump, is it possible to attach a seperate less sensative float switch with more tolerance and should I do so or are there any other suggestions? I replaced both pumps recently thinking that the old pumps had to be faulty but they behave in the same manner. Its terribly annoying haveing a continioius intermittant alarm whilst underway. Pse share your experince and advice. Much appreciated. Mike
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Old 08-04-2018, 08:40   #2
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Re: Bilge Pump Continiouslly switches On & Off.

Separate the alarm from the bilge pump switch so that the alarm only sounds when the bilge pump is not able to cope with the water level.
Many boats have this as a high water alarm combined with a high water high-capacity bilge pump.
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Old 08-04-2018, 08:53   #3
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Re: Bilge Pump Continiouslly switches On & Off.

You can also install an On Delay relay in the alarm circuit. This would energize the alarm after the bilge pump has run for a set period of time. You can get these at most autoparts stores. You want an NOTC (normally open timed close).

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Old 08-04-2018, 08:55   #4
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Re: Bilge Pump Continiouslly switches On & Off.

Bilge pumps dont pump out all the last bit of water. They pump it into the hose, then suck air, so shut off. When they shut off, the water in the exit hose runs back into the bilge. So the pump turns on again... etc etc.
Some people add a pickup tube type of small pump to get rid of the final water. These pumps are not centrifugal pumps like a bilge pump, so water doesnt flow back thru them much. They have the big pump raised up a bit for big water issues.
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Old 09-04-2018, 08:23   #5
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Re: Bilge Pump Continiouslly switches On & Off.

Cheechako, thats exactly what happens. The pump just runs contioniouslly on the backflow and water swishing around with movement of the boat is underway. The pump thus runs unnesisserily but does so continiouslly. Thanks for the replies. Any other comments / suggestions?
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Old 09-04-2018, 08:25   #6
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Re: Bilge Pump Continiouslly switches On & Off.

Quote:
Originally Posted by Cheechako View Post
Bilge pumps dont pump out all the last bit of water. They pump it into the hose, then suck air, so shut off. When they shut off, the water in the exit hose runs back into the bilge. So the pump turns on again... etc etc.
Some people add a pickup tube type of small pump to get rid of the final water. These pumps are not centrifugal pumps like a bilge pump, so water doesn't flow back thru them much. They have the big pump raised up a bit for big water issues.
I had a pump that did this. I fitted anon return valve near the pump so only a a small amount trickled back. I also lowered the outlet to near the waterline so I rely on this valve when heeled, not a problem I expect you entounter in a cat!
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Old 09-04-2018, 09:26   #7
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Re: Bilge Pump Continiouslly switches On & Off.

Hi. Sorry I don't have a solution but I had exactly the same problem with that model pump. If memory services, it is designed to activate every 2 minutes if it senses that there is still water in the bilge. There wasn't but the pump activated anyway. I looked at one way valves but they are not recommended. BTW, the setup on my boat had a smaller 500gph pump and the 1100gph pump wired together. The electrician said the two were wired together incorrectly. His solution was to remove the bigger pump. Also, when I bought the boat with this setup there was no problem. The problem started after Irma destroyed my dock which cut of the electricity which cutoff the air conditioning which fried my batteries in the heat and humidity.

Wish I could be more help.

Marshall
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Old 09-04-2018, 09:39   #8
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Re: Bilge Pump Continiouslly switches On & Off.

Either of these types as a small pump will solve your large pump cycling problem. Keeping the little bit of water out of the bilge.
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Old 09-04-2018, 09:43   #9
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Re: Bilge Pump Continiouslly switches On & Off.

I had a problem several years ago where the backfow in the discharge hose fed back into the bilge, reactivating the pump and continuing this cycle. Perhaps this is your problem. I solved mine with an electronic sensor rather than the float-type which allowed a bit more water in the bilge before activating the pump. The other solution is a backflow valve in the discharge hose, preventing the ........backflow.
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Old 09-04-2018, 10:11   #10
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Re: Bilge Pump Continiouslly switches On & Off.

Mike-

As others mentioned, these symptoms are often due to recycling water not completely discharged from the previous pump cycle [assuming no other constant source of water.]

A delay start relay will help some, and that is how our boat was set-up when we acquired it.

I took it a step further: I raised the 1100GPM submersible bilge pump and smart switch [with separate high water alarm...] about 6" off the bottom of the bilge- making it the new secondary bilge pump. [And there are 2- 4000 GPH pumps above it.]

For routine maintenance dewatering of the bilge, I installed a Whale IC bilge pump.

The main benefits are:
  • The pump is a robust diaphragm pump [i.e., can run dry and pump air/water mixed] and is never submerged
  • The submerged pick-up has a potted water sensor wired back to the pump
  • To help prevent cycling [as you describe] the pump has a ~9 second delay built in to ameliorate nuisance alarms from small amounts of water sloshing about
  • The pump runs for another ~45 seconds after the submerged sensor indicates no more water- effectively clearing the discharge hose so no water runs back into the bilge when the pump shuts off
  • Your current pump is no longer submerged and will likely last much longer as a stand-by pump.

If you do this, don't forget test regularly... We do so by turning off the lower pump[s] and adding water to bilge when cleaning to test the higher pump[s] in order high to low [and associated alarms.]

This also flushes some clean [fresh when possible] water through each of their independent discharge hoses; lets you time how long it takes each pump to dewater to its level in static situations; and determine what flow rate [from dock hose or washdown pump] your pumps can handle as a system [and the electrical draw...]

In case this is of interest.

Cheers! Bill
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Old 09-04-2018, 10:13   #11
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Re: Bilge Pump Continiouslly switches On & Off.

Suspect you are using a pump with built in float switch. Easiest solution I came up with was to use a remote float switch instead. Mount securely the pump at the lowest bilge level and secure the remote switch a few inches higher. Obviously that will require a slightly greater volume of water in your bilge, so add bilge cleaner, and as that water sloshes about, the bilge stays degreased.This works well unless you have excessive amounts of oil in your bilge. it also operates as an alarm system. If you are underway, for instance, and the pump activates more frequently than what you regard as normal, check your stuffing box for excessive leakage... or other sources of leakage (hoses, water tanks, etc). CAUTION: maintain a separate high water alarm higher in the bilge as a safety backup.
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Old 09-04-2018, 10:21   #12
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Re: Bilge Pump Continiouslly switches On & Off.

I had the same problem.

I think Brickbat is right that the switch to activate the pump could be an eletronic switch a little higher up (so not using a Rule type switch). After all your prblm is being caused by the water flowing back into the bilge down the tube from the pump which might be a little higher up. That has a fixed volume of water so if you put the switch higher up it will be higher than the run-back water. While it is not recommended because of debris blocking the system I added a non-return valve down in the bilge which immediately fixed the problem. Many will say you should not do this but i have had no problems with it. (If there were to be problems i have a manual bilge pump which sucks from the same position in the bilge).
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Old 09-04-2018, 10:49   #13
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Re: Bilge Pump Continiouslly switches On & Off.

I too have a non return valve. It usually works fine, however it occasionally causes a problem. If the pump completely empties the bilge and air gets into the pump the pump does not have enough force to overcome the weight of the water in the exhaust hose. For that reason I have positioned the float switch an inch or two higher than the pump. Of course that means a little water remains in the bilge. It is a deep sump so it is not an issue.

BTW. My bilge pump is a Rule 1500. It is 32 years old and still working. When I bought the boat 27 years ago it came with a spare. The spare is still in the box.
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Old 09-04-2018, 12:07   #14
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Re: Bilge Pump Continiouslly switches On & Off.

I looked up the specs for the pump I think you have and found this description:

>>These pumps boast "smart" operation, with an internal computer chip that cycles them on every 2 1/2 minutes, then quickly shuts them down if no water is detected. <<
So they are designed an built to cycle frequently.
I just put in a new bilge pump but have a separate, solid state, "float" switch which doesn't go on until there is about 3" of water in the well and shuts off when down to about 1".
Having the separate switch is an advantage since you can put it as high or low as you want.
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Old 09-04-2018, 12:08   #15
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Re: Bilge Pump Continiouslly switches On & Off.

Are you sure it uses a float switch? My Rule uses amp draw to determine if there is water. It will spin up every 90 seconds or so. If the amp draw is low (Pump not fighting water), it assumes there is no water and stops. If amp draw is high (Pump is pushing water), then it continues to spin until the amp draw falls.
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