Heavy duty construction for both commercial and pleasure boat use; known for trouble free operation and reliability. 1-1/2" (38mm) discharge outlet.
700 gallons per hour
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Comments about Rule 3700 Bilge Pump:
I initially installed a smaller Rule pump to pump water up a 5 foot head (vertical lift) out of my sailboat's bilge. The pump would whir away - but pumped no water. I then installed this monster: the biggest pump that would fit in the bilge. Same behavior, lots of whirring noise - no water pumped.
Rule blamed the problem on air locking: an effect where air gets trapped at the top of the pump chamber preventing priming of the pump. The only advice they offered was not use a backflow preventer and to make sure the hose had no "dips" that could trap water. The problem is: when the boat is heeled to port, the anti-siphon loop that Rule does recommend becomes a "dip". Rule must assume that no one sails in a monohull sailboat that heels. "Vertical" is a relative thing in a monohull sailboat.
Rule was of no further help in solving the problem. Emails from me went unanswered. I finally found the solution by consulting a master plumber. He took one look at the problem and said: "You need a weep hole. The weep hole is for evacuating air and facilitating priming." I drilled a 3/16ths inch hole in the hose directly downstream of the pump discharge port and, viola!, it pumps water. Yes, it leaks a little back into the bilge, but only a small percentage of the amount of water that goes overboard, and some water flow is better than none.
Advice: after installing your pump, put the garden hose in the bilge and see if the pump actually works! Finding a problem at the slip is better than finding it out on the water. And if the pump whirs away but pumps no water, drill a small hole in the hose next to the discharge port.
Comments about Rule 3700 Bilge Pump:
The problem with any submersible pump, is that at some point, guaranteed, your float switch will stick and your bilge will fill with water to a point above the wiring connectors. No matter how well you seal these from water, the wires will get wet and start to corrode. If you periodically re-terminate these, and you will have to when they fail, the wire must be cut shorter making it even more likely the wire will get wet again. So you are left with the dilemma of how short to cut the wire. Short enough to re-terminate the wire, or even shorter to find less corroded wire. I tend to try to keep the wire as long as possible.
I typically use UltimaSwitch automatically control the on/off. Even these fail. In fact, they fail too often. I thought this type of switch would last for a long time. These UltimaSwitches fail almost as often as a mechanical float switch.
I am presently using two RULE 3700, one on top of the other controlled with UltimaSwitches. If I had it to do over again, I'd use a non submersible pump so the wires never get wet. This is a more costly option, but well worth the extra expense if you want to keep your boat afloat.
If Rule sold a replacement wiring pig-tail and that wire was much longer, this would be an acceptable product.
The bottom line is these pumps are better than nothing, but do not trust them, and get a bilge alarm and make sure everyone near your boat has your phone number so you can bail it out when this pump craps out.
One final point. The bottom mount of this pump--the red portion is frail and weak. They sell replacements because they fail so frequently.
You decide. Do you want to spend a lot of money on this joke of a bilge pump, or put your money into a higher quality non submersible pump like a Jabsco.