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Author Topic:   Check valve
Arriba posted 08-14-2001 10:17 AM ET (US)   Profile for Arriba   Send Email to Arriba  
I have a Rule Platinum bilge pump and I need some help. The hose,1 1/8 inch inside diameter, runs from the pump up and overboard thru the hull fitting. The problem is the hose does not clear of all the water pumped. It returns to the bilge pump pit and the pump then figures there is more water and after the 2.5 minutes, pumps this again. It does not get out of the hose and once again returns to the pump pit and the cycle begins again. If this didn't occur the pump is smart enough it would merely check for water and not pump if it was not warranted. Does anyone have any suggestions how to keep the water in the hose from returning to the bilge pump pit. I would like to install a check valve as close to the pump as possible, but can't find any for a 1 1/8 inside diameter hose.
triblet posted 08-14-2001 10:37 AM ET (US)     Profile for triblet  Send Email to triblet     
That's not the way those pumps work. They
don't have a sensor to see if there's water.
They just try every three minutes or so, and
based on sensing the power required, they
can tell whether there's water and keep
pumping till there isn't water. Then try
again three minutes later.

However, IIRC, the Rule Platinum is a little
smarter yet. If on one pass it doesn't get
any water, it won't wait three minutes,
it will wait ten or so before trying again.
It will stay on a ten minute cycle until it
does get water, then go back to a three
minute cycle.

How many GPH? 1 1/8" seems pretty large
daimeter. Also, is the through hull well
above the waterline?


Arriba posted 08-14-2001 10:56 AM ET (US)     Profile for Arriba  Send Email to Arriba     
Thanks very much for the reply Triblet. You have my pump down pat. The pump is the largest capacity they make. I'm not taking any chances. Be prepared for the worst is my motto. Yes., the fitting is above the waterline. The hose rises approximately 2 feet from the pump in the pit,not directly up, but over a 3-4 ft length. The boat does not leak and when I sponge the pit to normalize the cycle the pit stays dry, unless we bring waterin the cockpit after swimming, etc. Any suggestions??
andygere posted 08-14-2001 11:54 AM ET (US)     Profile for andygere  Send Email to andygere     
You should be able to find a simple ball check or rubber flap check from an industrial plumbing supply house like Ryan Herco or Harrington. You may also find one in the Granger catalog. It will add some headloss, slightly reducing the capacity of the pump, but will probably solve the problem. Is there any way to shorten the hose run or eliminate some bends?
Arriba posted 08-14-2001 01:24 PM ET (US)     Profile for Arriba  Send Email to Arriba     
All right! Thanks andygere. I hadn't thought of a plumbing supply outfit. I've got it about as direct as I can get it. Would getting a 1 1/2 in check valve,then going from my 1 1/8 to the 1 1/2 check valve and then back down to the 1 1/8 hose be advisable or beneficial?
jameso posted 08-14-2001 04:40 PM ET (US)     Profile for jameso  Send Email to jameso     
Try raising the pump and inch or so in the well. You have a set amount of water in the hose/pump when it shuts off, this drains in the well and the cycle will continue until you sponge it out or it evaporates! By raising the pump an inch or so the pump will not pick up the small amount of water that is left over. You will still have an inch or so of water in the well and I don't know of a way to avoid it. This is a common problem with these pumps,,,guess I'm old fashioned,,,have a manual switch.
andygere posted 08-14-2001 04:49 PM ET (US)     Profile for andygere  Send Email to andygere     
If you can bush up instead of down, you reduce head loss, so its the way to go.
Arriba posted 08-16-2001 09:29 AM ET (US)     Profile for Arriba  Send Email to Arriba     
Jameso and andygere, thank you very much. I think the way to go is to raise the pump slightly. It is such a sensible answer to my problem. I called Rule and they suggested a vent loop. I'm not going that way. They told me,on my pump, a check valve could possibly cause an air lock. They did say the way it was operating now was not going to affect the pump other than I wouldn't be getting the pumps full range of ability. thanks again.
jimh posted 08-16-2001 08:14 PM ET (US)     Profile for jimh  Send Email to jimh     
I am visualizing this pump situation...

Imagine the pump is mounted at the top of a sump that is 100 feet deep. The pump runs until it clears all the water it can, that is until the impeller is spinning without water loading it down.

The pump shuts off. There are still 100 feet of water below the pump. The water in the exhaust hose runs back down, filling the sump just enough to get the pump running again. The cycle starts over.

Now, I follow the advice given here and I raise the pump abou an inch. What changes?
I have 100-feet and 1-inch of water below the pump. Does the pump know this?

No. The pump just runs like it always did.

I don't see how raising the pump is going to stop this cycle.

What is really determining this endless cycle is this:

The volume of water in the exhaust hose which flows back into the sump when the pump shuts off has to be reduced so that when it re-enters the sump it does not cause the level of the sump to rise enough to re-trigger the pump.

The easiest way to do this is to shorten the exhaust hose so there is less water stored in it.

Or, increase the diameter of the sump area so that when the water from the hose returns it spreads over a large diameter area and does not cause any significant rise in level.

Absent some change like this, I don't see how just raising the pump will affect this feedback-loop situation.


lhg posted 08-16-2001 09:16 PM ET (US)     Profile for lhg    
Agree with Jim - this is an 1100GPH pump ( I have one also) and you have a combination of too much rise (problably too close to the thru-hull fitting and too much length, plus a small surface area of the bilge sump. With any bilge pump, the volume of water in the "rise" area of the hose will flow back into the sump when the power goes off.

If you can, the way to fix this is to accomplish the total vertical rise as close to the pump as possible, with the rest of distance running almost horizontally. That way the hose won't hold much water, and won't dump as much back in the sump when the power goes off.

As a last alternative, you can buy a Rule hose reduction fitting, to neck the pump discharge down to 3/4" hose. This diameter hose will only hold half the volume of water of the 1 1/8" hose. The pump will lose some efficiency in it's 1100GPH output, but your problem will be solved.

Arriba posted 08-17-2001 09:53 AM ET (US)     Profile for Arriba  Send Email to Arriba     
jimh & Ihg, well, I sure didn't catch that result of pump raising. my wife keeps telling me its hard to get good help. I can't increase the pit area so I'll try repositioning the hose or possibly reducing to a smaller hose. Thanks again for your help.

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