Return Plumbing Question

[jiperalta]

Setting up a 65 with overflow box. The return hole is 3/4" and the pump output is 1".

Is it better to put the 1" to 3/4" converter at the pump outlet and plumb with 3/4" from there or plumb 1" pipe to the bulkhead and place the converter there?

Any difference in flow and is either better for minimizing pump strain?

Thanks in advance.

[richie z]

going from a larger hole to a smaller hole will increase flow(venturi efect) going from a smaller hole to a larger one will reduce flow rate

[jiperalta]

Thanks, I'm not quite that dumb. I am wondering if there are any advantages/disadvantages to the actual placement of the flow restrictor.

[RedEDGE2k1]

People are likely to ignore your request for assistance, given your attitude after the first offering of help.

[richie z]

sorry if it sounded like i was saying you were dumb, im from newcastle most peaple i talk to grunt. i have my reducer at the pump.

[jiperalta]

red, what attitude? I was poking fun at myself...

thanks, richie

[NeveSSL]

Originally posted by jiperalta
red, what attitude? I was poking fun at myself...

thanks, richie

Use the emoticons to emphasize this.

See?

Brandon

[kgross]

The answer to the question is do you want to maximize the flow from your pump? If you do, you will use the 1 inch, or even better move up to 1 1/4 inc pipe all the way to the 3/4 inch bulkhead then reduce down to 3/4 as it goes into the tank. The friction loss in the 1 or 1 1/4 inch pipe will be much less than in the same length of 3/4 inch pipe so you will get more flow out of your pump. personally I would suggest not useing the 3/4 inch bulkhead for your return use it for a second backup drain and plumb your return up over the top of the tank. What flow rate are you planning on running through your sump system?

Kim

[kcress]

jiperalta; Sounds like you are making the common mistake of thinking that restricting a centrifugal pump's output puts some sort of strain on it. On the contrary the more restriction, the less work the pump has to do, and the easier its life becomes.

Realize that the Work a pump does is moving mass,(water). If you restrict it, less mass is moved, hence less work is done, less "strain" whatever the heck that is.

Now if you want more flow then then just as kgross suggests make the exit (return) as large as possible. You can run up over the top but all the 90s will be restrictive in their own right. If you run larger pipe up to the bulkhead, what happens is the water coming up to the bulkhead is motoring along then hits the bulkhead restriction. It will act like a fire nozzle forcing the water to greatly accelerate in an attempt to sustain the flow from the riser. When this happens into an open tank there isn't a big flow restriction like there would be when reducing the flow by going into some "length" of smaller pipe where the accelerated flow would lose a lot of energy running down the sides of the pipe.

Recapping: Return line restrictions make a pump's life easier but reduces the throughput - probably not why you bought that size pump.

Running a restriction into a large body of water will result in the least reduction of flow verses a length of reduced piping.

[jiperalta]

thanks for the responses. I knew not taking fluid mechanics in college would come back to bite me in the rear one day...

so, either put off the restriction as long as possible or avoid it all together by plumbing up and over the back.

for whomever asked, i'm shooting for 5x on a 65 gal with a 1" outflow bulkhead and a 3/4" return bulkhead.

the "strain" I was worried about was whether placing the restrictor at the pump output would create sufficient back pressure to either break the impeller or shorten the life of the pump.

[richie z]

my return pipe goes up and over like suggested before by some one it works fine