Plumbing Changes For Pump Replacement

thenomad512

New member
Apr 26, 2025
2
Mooresville, NC
Hey there everyone,

I've been lurking for about a year and have learned so much from this community on maintaining the 15k gallon in ground pool we inherited when we moved. After maintaining with liquid chlorine the last year, I decided to put a SWG in for this season. Since I was already on the upgrade train and Duke increased their incentive for energy star pumps, I bought one and am looking to replace the 17-year-old Pentair pump they had in there. Looking at the manual for the new pump, it's telling me I should have 12.5 inches of straight pipe before the inlet (2.5" OD). How critical is this? The new pump has a coupler so I will need to modify the current pump inlet anyway but, it's currently a lot closer to that 3-way valve than the manufacturer recommends.

After we got the place I had to fix several suction side leaks including cracked 3-way valve housings and I basically replumbed the same way the builder had it but, added the 90 degree sweeps with new valves (please feel free to laugh at my horrible PVC cement job!).

I'm looking for some opinions on if I should just add the coupler to the short inlet pipe and be done with it? The new pump has the same inlet/outlet configuration so I would just have to add the coupler that came with the pump.

Alternatively, I am thinking about re-plumbing to extend the straight inlet section to 12.5" and move the 3-way valves back in line with the 3 supply lines from the main/skimmers. At the same time, I would replace the pump outlet plumbing to add sweeps, move the hose fitting, possibly get rid of the 2-way valve that goes to the vacuum port (seems redundant?), replace the canister that's leaking, and replace the coupling that goes to the spider valve.

See my pictures, hopefully they give a better picture of what's in my head. (The circuit on the left with the black jandy pump is separate for a waterfall. I have no idea why it was done that way but, that's what the owners did when they built the place. I have a bunch of other problems from the winter with this that I'll save for a separate post hah). Unfortunately, I think I would have to throw out those two new jandy valves I just replaced if I moved everything but, also seems like a good opportunity to streamline the plumbing?
 

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Welcome to the forum.
Have you had issues with the existing pump priming? That would be the only effect of poor suction (inlet) piping.
Depending on what VS pump you have, you should be able to reduce priming rpm and time. Also you will likely run the VS pump at a lower rpm. All of those things reduce the issues with the suction plumbing.
 
Welcome to the forum.
Have you had issues with the existing pump priming? That would be the only effect of poor suction (inlet) piping.
Depending on what VS pump you have, you should be able to reduce priming rpm and time. Also you will likely run the VS pump at a lower rpm. All of those things reduce the issues with the suction plumbing.
Thanks!

The current pump will still slowly lose prime after being shut off. I recently replaced the pump lid and drain plug seals but, there is still a small leak that I suspect is from the threaded inlet because I can see bubbles slowly coming from the inlet pipe after the pump shuts off. When it comes back on, it's able to re-prime in about 30 seconds.

Prior to replacing the 3-way valves last year, it would take several minutes running before it would get going again.

EDIT: I forgot to add that the new pump is a 2 HP Circupool VS pump.