Submersible pump and flow sleeve in a cistern

[grover]

I'm putting a submersible pump in my cistern and I need to design a flow sleeve for it. My pump is 1/2 hp 10gpm and it is 3.75 inches in diameter. Will a 4 inch PVC sched 40 pipe be enough diameter to get enough flow around it. Seems 1/8 inch on the sides is very little.
Also the pump manufacturer advised my to put the pump in a vertical position. Everyone I see doing this in a cistern is putting the pump in horizontally or with a slight incline.

What do you think?

 

[Reach4]

I'm putting a submersible pump in my cistern and I need to design a flow sleeve for it. My pump is 1/2 hp 10gpm and it is 3.75 inches in diameter. Will a 4 inch PVC sched 40 pipe be enough diameter to get enough flow around it. Seems 1/8 inch on the sides is very little.

Plenty.

Other good piping would be
solvent weld D2729 sewer pipe: OD 4.215 ID 4.056 ( white or green)
SDR 35 OD: 4.215 ID 3.97 SDR 35 (PS46) ASTM D3034

I computed the area in the pipe. Subtracted the area of the motor. The difference is the "annular space" where water can flow. For comparison, the area of a 1.25 inch diameter circle is 1.227 in².

 

[Sponsor]

 

[grover]

Thanks, I wasn't really expecting that much detail but good to know the numbers.
So if my discharge pipe is 1 1/4 sch 40 (1.36ID) then that area would be about 1.45 sq in. That would mean if I use sch 40 or D2729 for the sleeve it should provide more flow that my discharge pipe can handle.
6 inch pvc is a lot more expensive than 4 inch.

 

[Reach4]

The main point of the flow inducer is to run water right by the motor, which maximizes cooling. So 4 inch is better than 6 inch for this job.

In a well it can have some additional advantages, but not in a cistern.

Those thinner pipes are easier to draw in with the big hose clamp. Schedule 40 will need more saw kerfs to make it springier, I think.

 

[Greenmonster123]

I'm putting a submersible pump in my cistern and I need to design a flow sleeve for it. My pump is 1/2 hp 10gpm and it is 3.75 inches in diameter. Will a 4 inch PVC sched 40 pipe be enough diameter to get enough flow around it. Seems 1/8 inch on the sides is very little.
Also the pump manufacturer advised my to put the pump in a vertical position. Everyone I see doing this in a cistern is putting the pump in horizontally or with a slight incline.

What do you think?

i wouldn’t worry much about it I have 4” wells with 75 gpm pumps in them

 

[grover]

I’m planning to use a 4 to 3 inch rubber boot from sleeve to pump and splitting it where the wires come through instead of making slits in the pipe. Undecided about how to center the pump at the bottom.

 

[Reach4]

I’m planning to use a 4 to 3 inch rubber boot from sleeve to pump and splitting it where the wires come through instead of making slits in the pipe. Undecided about how to center the pump at the bottom.

Not needed, but if you want to do that, I would use three stainless or brass screws and nuts.

 

[LLigetfa]

Not needed, but if you want to do that, I would use three stainless or brass screws and nuts.

Agree that it is not needed. I would not use metal that would rub against the motor. Just heat up a small area and form a dimple.

 

[grover]

I like the idea of heating the pipe and putting dimples in for the centering.

 

[Fitter30]

Plenty.

Other good piping would be
solvent weld D2729 sewer pipe: OD 4.215 ID 4.056 ( white or green)
SDR 35 OD: 4.215 ID 3.97 SDR 35 (PS46) ASTM D3034

I computed the area in the pipe. Subtracted the area of the motor. The difference is the "annular space" where water can flow. For comparison, the area of a 1.25 inch diameter circle is 1.227 in².

Why does a submersible pump need a sleeve? Don't have a clue?

 

[Bannerman]

Why does a submersible pump need a sleeve?

To ensure sufficient water flow across the electric motor to provide cooling for the motor.

Because the inlet to the pump is normally located at the center of the pump's height, a well that feeds from above the pump location, will provide little water movement below the pump inlet where the electric motor is located. In the situation with placing the pump within a cistern, water will be drawn from all directions surrounding the pump intake, providing little cooling for the motor.

 

[grover]

I'm a little concerned about the plumbing inside the cistern now. The cistern is buried with the top at ground level. It gets near zero in our coldest part of the winter here. will my pipes freeze inside the cistern. Plan was to put a quick connect union near the manhole cover to be able to pull the pump if needed. Will the ground temps keep it warm enough inside to protect pipes?

 

[Reach4]

I'm a little concerned about the plumbing inside the cistern now. The cistern is buried with the top at ground level. It gets near zero in our coldest part of the winter here. will my pipes freeze inside the cistern. Plan was to put a quick connect union near the manhole cover to be able to pull the pump if needed. Will the ground temps keep it warm enough inside to protect pipes?

You could build a well-insulated cover, but that would need to extend out some.

Better, you can put a pitless adapter through the side of the cistern below the frost line. The wires can come over the top . How high does the water get with respect to ground level? https://terrylove.com/forums/index....-dug-well-and-adding-a-pitless-adaptor.89592/

Pulling the pump is fairly easy that way.

 

[grover]

I'm finding very little online with respect to using a pitless adaptor in a cistern or tank. My manhole may not be near the water line entrance so there would be nothing much to hold the supply line down when pulling the pump. Maybe a line running from the supply to the underside of the top of the tank near the manhole. Hope that makes sense.
Should galvanized water lines be used inside the cistern to be a little less flexible?

More research...

 

[Reach4]

Describe your cistern. Confirm you do not have a pit with a well in it. How does water get into the cistern?

How high does the water get with respect to ground level?

I'm finding very little online with respect to using a pitless adaptor in a cistern or tank. My manhole may not be near the water line entrance so there would be nothing much to hold the supply line down when pulling the pump. Maybe a line running from the supply to the underside of the top of the tank near the manhole.

I was picturing running the supply line outside of the cistern underground. So the pitless would be placed at a spot consistent to access via the manhole. The pipe/nipple thru the cistern wall would hold the pitless in place.

How were you picturing running a line to the pump without the line freezing? Is there an underground pipe, and you planned to use a flexible line to connect to the pump?

 

[grover]

Concrete cistern will be filled with hauled water for now. No well. the top of the cistern is visible, the rest is underground. The fitting for the supply line is below the frost line. I don't know how close the fitting is in the side of the tank to the manhole cover. Normally in a well the supply line is below the frost line but there is a T in the line through the casing so there is no up and down play in the supply line. In a cistern the supply pipe will have to be brought over to the manhole cover. I'll have to check next time I'm there but I was thinking 3-4 feet distance at least. A horizontal supply line would have a lot of up and down play unless you had some device to hold the supply line while pulling and/or installing the pump using a pitless adaptor. I've never done this so this is all in my little pea brain.

 

[Reach4]

OK. So it seems to me like it will probably be a problem running the out put of that cistern through the side thru the existing bulkhead fitting. You could look the fitting inside.

I am not sure a pitless adapter will help either. But how do you plan to get water out of the cistern?

Also, if I were putting a submersible pump into that cistern, I would want it horizontal so that I could pump lower, unless you are planning to use one of those Franklin C1 pumps. https://terrylove.com/forums/index....-pump-in-cistern-mounting-installation.23621/

 

[grover]

Plan is to enter the cistern through a theaded fitting on the side below the frost line. Then over to the area of the manhole cover. Then 90 up to the cover, 90 into a union fitting, then 90 down to the pump set vertically recommended by the pump manufacturer.

 

[Bannerman]

Valveman supplied the diagram below, which shows a submersible pump placed within a cistern. Although the cistern is shown above ground, the configuration could be easily adapted for an in-ground cistern where the supply line to the home will be buried.

The pressure tank, pressure switch and CSV would be located within the home or other temperature controlled location to prevent freezing.

Since the water inlet for a submersible pump is usually located between the electric motor and the pump, a submersible pump installed vertically within a cistern, will not be capable of accessing the water at the bottom of the cistern, below the water inlet. Placing the pump horizontally will allow access to additional water located near the bottom of the cistern.

 

[Reach4]

Then 90 up to the cover, 90 into a union fitting,

It seems that area near the cover could be freezing.

Suppose a pipe would enter the cistern through a threaded fitting on the side below the frost line, as with your current plan. Then over to the area of the manhole cover. Then horizontally into a pitless, which is below the frost line. mating part of the pitless holds the pump. The o-ring seals.

Pull pipe is only in place when the cover is open.