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Old 16-07-2011, 18:27   #1
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Raw Water Pump Inlet / Outlet ?

Hey all! OK, call me an idiot, but on a water pump">raw water pump such as this one (Sherwood G7b), which one is the inlet, and which is the outlet? The pump is not marked, nor are their instructions and their mech drawing... Thanks, Chris
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Old 16-07-2011, 18:33   #2
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Re: Raw water pump inlet / outlet?

if it is not marked with direction arrows i assume in and out would be determined by the direction of rotation you choose.
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Old 16-07-2011, 19:05   #3
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Re: Raw water pump inlet / outlet?

The output is where the water come out. The inlet is the other one. It runs either way.
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Old 16-07-2011, 19:27   #4
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Quote:
Originally Posted by daddle
The output is where the water come out. The inlet is the other one. It runs either way.
Well, so I thought. Look at the pic. If the pump is turned clockwise ( from this direction ) you would think that the inlet is on our left, and the outlet is on our right. No, I believe this is exactly backwards...
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Old 16-07-2011, 19:44   #5
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Re: Raw water pump inlet / outlet?

Wheres the impellor cover? you should be able to take that off and logic it out....
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Old 16-07-2011, 19:54   #6
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Re: Raw water pump inlet / outlet?

Nope. Yes. You turn that clockwise, in the picture view, and the water will flow to the left. Put some water in the right side and give it a turn. The water is transported the long way around the bottom of the pump. You should take the cover off and see for yourself the clever way these pumps work.
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Old 16-07-2011, 19:54   #7
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Re: Raw water pump inlet / outlet?

After a few minutes on Google I was surprised to find statements that this pump is bi-rotational.

Use the search phrase "Sherwood G7b bi-rotational pump" and you can see examples such as,

... All Series G pumps are capable of bi-rotational flow without modification ...


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Old 16-07-2011, 20:29   #8
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... All Series G pumps are capable of bi-rotational flow without modification ...
Funny thing, I did the google search, and among others, came up with several posts such as this: http://my.boatus.com/forum/forum_posts.asp?TID=58085 That also found the pump to only work in one direction... How screwed up is this???
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Old 16-07-2011, 20:33   #9
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Quote:
Originally Posted by daddle
Nope. Yes. You turn that clockwise, in the picture view, and the water will flow to the left. Put some water in the right side and give it a turn. The water is transported the long way around the bottom of the pump. You should take the cover off and see for yourself the clever way these pumps work.
I'm wondering if hooking up the inlet on the "short" side makes it harder for the pump to prime as opposed to the side that takes the water the long way around the bottom... Inside the pump there is a "ramp" or area at the top that compresses the impeller fins. Think about it... If it worked well forcing water over the top, what good would the whole bottom half of the pump be? ;-)
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Old 16-07-2011, 20:40   #10
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Re: Raw water pump inlet / outlet?

Well, that is screwed up.

But the example you mention is a forum post. Maybe that has some bearing. Could be others in your search are not forum posts.

The search phase I used returned results for James Town Distributors, marineparts,com, fisheriessupply,com, marinemanifold,com, and other vendors.

Clearly not conclusive but evidence just the same. Possibly it's not likely several vendors would be in error.

Though it's news to me that any pump is bi-rotational.

Edit,..... I just scanned the Sherwood tech guide pdf and found no reference to bi-rotation. I scanned it rather quickly.
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Old 16-07-2011, 20:56   #11
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I think they should cast an "inlet" and "outlet" into the pump, just for idiots like me... ;-)
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Old 16-07-2011, 21:07   #12
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Re: Raw Water Pump Inlet / Outlet ?

I am in error and only making things worse here.

After following the links in my search and looking more carefully I have made mistakes.

It is a completely different "G" series of pumps that the quote I stated is referencing. A double lobe design totally different from the G7B to which this thread is about.
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Old 16-07-2011, 21:08   #13
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Re: Raw Water Pump Inlet / Outlet ?

Quote:
Originally Posted by Christian Van H View Post
I think they should cast an "inlet" and "outlet" into the pump, just for idiots like me... ;-)
But your comments in post 9 make a lot of sense.

I have trouble believing this pump goes both ways.

I'd have to disassemble it to figure it out.
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Old 16-07-2011, 21:10   #14
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Re: Raw Water Pump Inlet / Outlet ?

These pumps can typically be operated in either direction. It's the nature of the design. Of course the water flow changes direction as the rotation changes direction.

This is why they don't label it. Mine has arrows going both directions around the 'bottom'.

Some of you are making this too complicated. The guy in the linked post made a mistake.

It's pretty easy to test with a little water and a turn of the wrist. Sheesh.

I've never liked the stress of reversing the rotation of the impeller. It's ugly to watch with the cover off and can't be good for the impeller.
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Old 16-07-2011, 21:17   #15
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Quote:
Originally Posted by daddle
This is why they don't label it. Mine has arrows going both directions around the 'bottom'.
Daddle, I think you hit the nail on the head. Yes, they work in either direction, just so long as you have then pump connected so the water flows "around the bottom" and you are not trying to pump it "over the top"... There IS a difference...
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