Bilge Pump Situation

[Nibiruwayne]

Hey, just installed a new Rule 3000 gph bilge pump with the built in float switch. I also put in an inline check valve plus ran the hose with an anti-siphon break. I have heard it is incorrect to install an inline check valve in a bilge pump system. I did it to eliminate drain back into the bilge when the pump cuts off. The pump has to pump to a vertical height of about 4' before it makes the top of the siphon break.
Any thoughts out there?

[sabray]

The anti siphon would be there if your pumping below water line not great if that's the set up.. Prefer it if the pump discharges as high ad possible and above the water line.. I hate having a check valve in line avoid that if possible

[cal40john]

The manuals I've seen that come with Rule pumps say no check valve. Other companies say it's ok. One of the problems is that the weight of the water on the check valve can keep the pump from pumping if there is air in the pump. Centrifugal pumps don't pump an air water mix well, so it might not overcome the head and the air can't escape up the hose. My theory why some companies say that it is ok to use check valves is that the design of the pump somehow allows the air out or can never trap it in the first place.


Here's someone with 4 reasons:
Resist Using Check Valves


What has become recommended is to mount a small pump with a small hose in the lowest part of the bilge to make the bilge as dry as possible, and mount your bigger pump up higher for a more serious leak.

As the other poster said, no anti-siphon needed unless your outlet can go underwater. The recommendation in your Rule manual is if the outlet comes within 12" of the waterline worst case, i.e. heeled over, then you need the loop.

Just has pictures but your manual had all this information in it. You should have one of these with your pump:
http://lib.store.yahoo.net/lib/kingp...ump-Manual.pdf

[HopCar]

"What has become recommended is to mount a small pump with a small hose in the lowest part of the bilge to make the bilge as dry as possible, and mount your bigger pump up higher for a more serious leak."
Exactly right! With luck the big pump never comes on.

[Nibiruwayne]

Thanks sabray and cal 40. Weight of water against check valve makes sense.
My overboard is in a manifold and at the waterline so loop to rail is necessary, but i can see check valve is a bad idea. I already have a smaller whale gulper under the engine block to suck it dry.
Thanks for the advice.

[barnakiel]

We do not use the valve. We do not use the siphon. The hose goes up to exit which is above waterplane at all times.

It all depends on boat specifics but I would try to avoid the valve if feasible.

b.

[four winds]

I was going to mention number 4 from the link above. I've witnessed the benefit of this while working on my boat.

"The fourth problem with check valves is that they inhibit a good thing. All that water rushing back down the discharge pipe backflushes the debris screen(s) at the intake to the pump. Mostly these screens do not get clogged and this is why."