Help with pump/tank for rain cistern

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lcuga13

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I am trying to figure out how to easily modify a rainwater cistern to operate similar to a well pump system. Here is what the cistern looks like in place
raintank1.jpg


The incoming downspout is diverted into the manhole in the cistern. There is a custom filter basket in the manhole on top that separates the bulk of incoming debris. The lower plumbing assembly attached to the bulkhead in the tank is as follows: a tee with a vertical tube in order to view the water level inside the tank, another tee with a plug for cleanout on front, off to the side is ball valve, and the final part is a male hose connector. The braided water hose is to connect to an irrigation centrifugal pump so that the homeowner can pump the water through a regular garden hose to a sprinkler or simply an open hose.

The problem is that with that type of pump, it is either on or off. Once the pump is turned on, the flow will obviously continue until the pump is switched off. You cannot put a nozzle on the end and shut off the flow, as there is no pressure switch on the pump.

I would like to try and modify the system to use a jet pump with pressure tank and pressure switch. After browsing around Grainger's site, I located this pump http://www.grainger.com/Grainger/items/4TB35 . I considered building a small pump house enclosure for the pump and tank and putting a hose bibb on the outside of the enclosure. The pump would then cycle itself on and off according to the water demands, much easier than simply using a booster pump as it is now.

Does anyone have any opinions as to how to best hook up a pump like this to a cistern as seen in the photo? If I wanted to use the foot valve, I figure I would have to drop the line in through the top of the tank, maybe use another bulkhead up there. Am I correct that if I wanted to come off the lower plumbing assembly, would a check valve inline serve the same purpose as the foot valve? Does anyone know if there is a float valve that could be tied in to the power supply that would also reach into the cistern and shut off the supply when the water supply is out? I wouldn't want to forget and leave the pump running, to then use up the water and burn up the pump.

Thanks for any advice and help,
Lyle
 

Masterpumpman

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Jet Pump!

You'll only need a check valve on the lower cistern drain, then connect a shallow well jet pump to the check valve. Be sure to use a small pressure tank (to make it automatic). I would replace the existing pressure switch with a low pressure cut-off switch (this will cut your pump off when there's no more water). To keep the pump from cycling I would install a Cycle Stop Valve between the pump and the tank (Note: The pressure switch water line must be moved from the side of the pump to between the Cycle Stop Valve and the tank).

I suggest that you go to www.cyclestopvalves.com for more information.
 
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Themp

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All you really need to do is use the existing pump and supply a return line back to the cistern using a T. This return line has a ball valve so you can regulate the flow, the line can be a 1/4 inch flexible line. So, you have a line that feeds the hose and a return line and when the hose is cut off. The return line handles the pump and keeps it from burning up. Adjust the return line ball value so the pump does not cavitate when the hose is shut off.

Since the cistern is sitting outside you have to remove the pump when not using it I assume, so leaving the pump on accidently is likely not to happen.

Tom
 

cityfarmer123

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I realize this is a late response, but to future readers, there is some really impressive technology these days coming out of Europe for cistern/rainwater pumps. Grundfos, in particular, makes some really nice jet pumps and submersible pumps that don't require a pressure tank or pressure switch to operate. Instead, they use a built-in flow switch to detect when water is demanded, and turn on accordingly, and then turn back off when valve closes. The Grundfos MQ pump (www.rainbrothers.com sells them) is the jet pump version, and the Grundfos SBA pump is the submersible version... either of which would work in this -- or similar -- situation(s). Hope this helps and happy harvesting!
 

Valveman

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There are also many threads you can read about all different types of pump controls. We have discussed everything from the flow switch in the MQ to variable frequency drives. You might have a little catching up to do. For one thing that MQ pump is no longer available. It has been replaced with the Scala2, and we have discussed both at length. We have also weeded through most of the tankless gizmos.

It is becoming more well known that the old reliable pressure tank/pressure switch with a regular jet pump or submersible is about the most bullet proof and long lasting system there is. The only negative of the pressure tank system was that it would cycle at low flow rates. And the answer to that has been around for 25 years now.

But many people like you have not heard of the Cycle Stop Valve because it was blacklisted by the pump manufacturers in 1994. They said "the CSV makes pumps last longer and uses much smaller pressure tanks. This company makes pumps and tanks, so any employee that mentions one will be fired immediately." Since then they have been busy making "flow switch/tankless/state of the art/variable speed, etc. controllers. Pretty much anyway you can think of to deliver the same benefits as a Cycle Stop Valve, without making the pump last longer, as that would shoot their planned obsolescence and cash flow in the foot.

Here is just one of the last threads discussing the MQ.
https://terrylove.com/forums/index.php?threads/please-consolidate-info-on-grundfos-mq3-45.73616/
 

cityfarmer123

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Hello again Valveman -- Not sure where you heard that the MQ pump is no longer available. Our supplier stocks them and we have about 15 in our inventory currently because we use them so frequently. But I am excited to read some threads and, as you say, catch up with the latest conversations.
As for CSVs, I am very familiar with them and have used them on several installs. I generally promote them, but we install for a lot of off-grid applications, so we prefer the use of larger pressure tanks in those scenarios rather than a CSV, simply to lessen the motor run time and conserve power while reducing motor start-up frequency.
 

Valveman

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I checked this morning and you are right, they still make the MQ. But my supplier no longer stocks them because he said they are on the way out. Just waiting for production on the Scala2 before they completely stop making them. But he stopped stocking them already mainly because he has had so many problems with them.

I agree with you on the solar powered systems. There you can store energy in a pressure tank almost as good as storing it in a battery. So you want the tank to fill with as many gallons as possible, as quickly as possible, to save batteries.

I am use to seeing those MQ pumps piled up in a dumpster like this.
IMG_0002.JPG
 
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