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Old 06-29-2008, 08:38 AM   #1
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Changing from 1 1/2" PVC to 2 1/2" PVC

I am installing a new pump for my pool. The current piping is 1 1/2" PVC however the pump requires 2 1/2". Is there a coupling that starts with 1 1/2" PVC and has a male end of 2 1/2"? What are suggestions for changing this PVC size?


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Old 06-29-2008, 10:01 AM   #2
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Are you sure you mean 2-1/2", not 2"?


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Old 06-29-2008, 10:45 AM   #3
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Just buy a 2 -1/2" coupler and throw a couple of bushings in it?
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Old 06-29-2008, 11:55 AM   #4
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Are you sure your not buying too big of pump for your plumbing? From my limited experience in this area, if your pump can not draw enough water, it will cavitate and not be very efficient.

From my Hayward pump manual ( a 1 1/2" line will flow between 50 to 65 gallons per minute, depending on if it is sucking or pushing the water. A 2 1/2" line will flow 103 to 129 gallons per minute - a big difference.

Do you know the specs of your new pump? On page 5 of the link I posted, you can see some of the specs I was talking about.

Hope this helps
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Old 06-30-2008, 10:39 AM   #5
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Make sure you actually need 2 1/2" pipe. The O.D. (outer diameter) of Schedule 40, the standard type, PVC is 2 3/8". The O.D. of 2 1/2" PVC is actually 2 7/8". I have a fairly large pool (20' x 40', with an 8' x 14' ell) and my pump is a 2". I have 2 skimmers and 1 main drain, all 1 1/2" lines, on the suction side and 1-1 1/2" return line for the jets and 1- 1 1/2" line for a Polaris. I have had no problems with the pump sizing.

In any case, you will have better luck using a coupling the size of the larger pipe, and getting a bushing, which goes inside one end of the coupling, to reduce to 1 1/2". Make sure you buy pressure fittings, not DWV (for drainage). Pressure fittings have a deeper glue socket than DWV.

I hope this helps.

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Last edited by mstplumber; 06-30-2008 at 10:41 AM. Reason: typo
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