# Pump Intake Dia. Question



## 440mag (Jan 29, 2018)

Hello all!

*Background*: we are the second owners of our house; the lake-draw irrigation system was here before we purchased; apparently the original owners never seemed to hire the same contractors twice; and as a result, I am constantly coming upon all manner of "surprises," "patches" and "quick fixes."

I am wondering if the fact our F & W Pump # CJ101D201 intake starts out as 1-1/2" but within a foot of length is *reduced* to 1-1/4" pipe (which runs out into the lake) is something that makes sense from a mechanical / pump draw perspective OR if some contractor that came behind the original installers simply switched to 1-1/4" pipe cuz "that's what he had on the truck" (which is exactly what's occurred in other areas on the estate …. :roll: )

Our pump is now not holding prime, the pvc has been exposed to UV light for 12 years now so, instead of simply chasing a small crack or clogged filter I am going to just replace all the pipe from the pump down into the water and including a new filter and flap valve …

Thing of it is, as the attached photos show, the intake pvc pipe entering the pump is 1-1/2" but about 12" toward the shoreline there is a "reducer" fitting so that the intake pipe going into lake is really only 1-1/4" …

*Question*: if the intake opening on our F & W Pump # CJ101D201 is female NPT 1-1/2" and I am going to replace th*e entire intake pipe, all the way to the terminal end with the filter and flap / stop valve on it, should I go with all 1-1/2" pvc OR IS THERE SOME REASON THAT WOULD EXPLAIN WHY THE EXISTING INTAKE IS REDUCED TO 1-1/4" ???*

Thanks in advance - thought I had someone who does this with his eyes closed lined up to do it for good $ but sadly, it appears he is no longer dependable …


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## Justmatson (Apr 4, 2020)

Cost!
Or already had the 1 ¼" pvc on hand.

With any pump go with the diameter of the suction side of the pump or even bigger. Pump that size stick with the 1 ½"
When you lower the diameter it can cause cavitation (staving the pump) and premature wear on the pump, as well lower flow rate.


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## 440mag (Jan 29, 2018)

@Justmatson Thank You!

Sad to say I know those 1-1/4" pipes have been in place since at least 2014 when we bought the place but, the good news is the 1-1/4" will soon be gone and everything will be 1-1/2" from the pump to the intake filter, very soon!


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## TampaBayFL (Jul 24, 2020)

Since it sounds like you are redoing all the piping anyway, while you are at it if you can make the section of piping going into the inlet of the pump have a much longer straight section (instead of having that elbow right at the inlet), you will improve things as well.


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## 440mag (Jan 29, 2018)

Howdy @TampaBayFL and Wow!

So few words and yet such potential impact (now I'm double appreciative I posted my query here!)

In faaaaaaaaact, I picked up 20' of 1-1/2" pvc hose from Tractor Supply to replace the first 20' of rigid pipe as I suspect the sharp incline of the shoreline may have caused eventual cracks in any of the pipe connections.

My dilemma (until I got your post) was the fact it is not 20' down to the water and I was trying to figure out where I would put the hose bib I will use to prime to system each Spring.

So now, instead of having a 90^ elbow come off the pump and connecting the hose to that, I think I will have the hose come straight off the pump and make a gradual curve down to the rigid pipe at the waters edge.

Thinking I'll make a big "C" - as opposed to a sharp "L" - with the 20' of hose.

Doing ^that^ will allow me to "use up" the excess hose and install the priming bib above the water line!

Thank YOU!!!!


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## ScottieBones (Apr 2, 2020)

440mag said:


> Howdy @TampaBayFL and Wow!
> 
> So few words and yet such potential impact (now I'm double appreciative I posted my query here!)
> 
> ...


I have nearly same lake fed setup as you and also replaced rigid with a flexible hose. I even disconnect it and submerge in the lake for winter 😅


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## 440mag (Jan 29, 2018)

ScottieBones said:


> I have nearly same lake fed setup as you and also replaced rigid with a flexible hose. I even disconnect it and submerge in the lake for winter 😅


Okay, now THAT's ingenious!

One less thing for me to worry about while we're away winters - YESSSSSS!!!!!!!!


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