Straight pipe before pump?

[lastdon87]

My builder didn't put the 10-12 inches of straight pipe on the suction side of our pump. This is a new build that isn't finished yet, do I make them redesign it somehow? The plumber told me that's how they normally do it, and haven't had any issues, I just know once all the $$$ is handed over that making any changes will be more of a struggle. Thanks in advance for your thoughts.

 

[gwegan]

A quote from MAS985 one of our resident pump experts:

IMHO, the pipe in front of the pump has little bearing on cavitation or any other issues with pumps. It is something that is recommended in the water distribution industry where the pumps are much larger and much more prone to cavitation and they don't use a pump basket so the flow into the impeller is directly related to the plumbing attached to the impeller inlet. A residential pool pump has a pump basket which completely changes the fluid dynamics into the impeller inlet so the plumbing ahead of the basket has little impact to the flow dynamics other than head loss. Plus the turbulence in a typical pump basket overwhelms any benefit that a straight piece of pipe might have. Although some pump manufactures continue to recommend it for residential pool pumps, there is little evidence that it makes any difference at all. Most installers of pumps ignore this recommendation without any deleterious effects whatsoever. I would make the straight piece as long as you can but don't get overly concerned about it and don't add any extra fittings to get a longer piece either.

 

[lastdon87]

A quote from MAS985 one of our resident pump experts:

IMHO, the pipe in front of the pump has little bearing on cavitation or any other issues with pumps. It is something that is recommended in the water distribution industry where the pumps are much larger and much more prone to cavitation and they don't use a pump basket so the flow into the impeller is directly related to the plumbing attached to the impeller inlet. A residential pool pump has a pump basket which completely changes the fluid dynamics into the impeller inlet so the plumbing ahead of the basket has little impact to the flow dynamics other than head loss. Plus the turbulence in a typical pump basket overwhelms any benefit that a straight piece of pipe might have. Although some pump manufactures continue to recommend it for residential pool pumps, there is little evidence that it makes any difference at all. Most installers of pumps ignore this recommendation without any deleterious effects whatsoever. I would make the straight piece as long as you can but don't get overly concerned about it and don't add any extra fittings to get a longer piece either.

Thanks so much Gwegan....this is the info I was looking/hoping for!

 

[JamesW]

Why only one pipe going in to the pump?

 

[Patrick_B]

Good question....

 

[gwegan]

I suspect the main drain is plumbed to the skimmer

 

[banditig]

Yes whats up with one suction pipe, is there pipes combined burried in the ground?

Oh I see now its a special skimmer. Very interesting.
http://www.1paramount.com/products/venturiskimmer/

 

[Cinic]

Not to hijack, but what's the round gray thing with the black lid right next to where the conduit comes out of the ground?

 

[lastdon87]

Not to hijack, but what's the round gray thing with the black lid right next to where the conduit comes out of the ground?

That's the in-floor value, pretty sure.

- - - Updated - - -

Yes whats up with one suction pipe, is there pipes combined burried in the ground?

Oh I see now its a special skimmer. Very interesting.
http://www.1paramount.com/products/venturiskimmer/

It is a venturi skimmer from a&a..., and the in-floor leaf Vac is now in between the pump and the 2 pipes right in front of the pump, with a jandy 3 way valve to control suction from drain or skimmer (best I understand). Thanks y'all for the comments, definitely want to catch any problems before all money is paid out.

 

[ewkearns]

My builder didn't put the 10-12 inches of straight pipe on the suction side of our pump.

Actually, it should be 5-10 times the diameter of the pipe. However, since there is a strainer basket attached to the inlet of the pump, inlet piping just isn't all that critical.

 

[banditig]

That venturi skimmer looks kinda like a well jet pump. Does the water from the pump to skimmer get filtered or straight from pump?

 

[lpennock]

Venturi skimmer should be plumbed so it has a suction on the bottom that is turned off normally. The jet should be on the filtered side. I like to feed it post chlorination as I always found it strange to send unclorinated water back to the pool. My builder used the unclorinated water to feed the jet but I redid it when replacing a stuck ball valve.

Leonard Pennock (AD7AS)
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