Pressure tank for a two-wire pump system

[Drew]

Howdy folks,

I have a Grundfos submersible 2-wire well pump that works like a champ.  I plug it into my generator and it goes.  I'm trying to find a little information on the how to set it up with a pressure tank.  The tank would fill automatically and stop filling when it was full, all through the glory of the pressure switch that turns the pump on and off.

As I understand things, 3-wire pumps have a separate controller box while 2-wire pumps have the controller in the pump itself.  I've been looking for information on how to put this all together for my 2-wire pump without the controller box.

Have any of you done this before?  Do you know of a good source for information?

Gracias,

Drew

[NM_Shooter]

Hi Drew,

When you say a pressure tank, do you mean an accumulator for a well?  It is a large sealed metal tank with a bladder in it? 

Does your pump have the pressure switch built into it?  That sounds a bit odd to me if it is a submersible pump. 

I should have read your post better before writing this, as now I am wondering about your application.  If this is a pump that goes down into a well, then the height above the surface of the water to which you are pumping (head) is going to affect how much pressure you get at the top end.  Is this a positive displacement pump?

Are you pumping from down a well or a lake?  If you don't have to raise your column of water much, and your pressure switch is in the pump, you should be good to go.

Put your accumulator up by your end use of water (near / in your cabin?).  Run your H2O supply line from the pump up to the tank, and Tee off to attach the tank. 

I am hoping that your pump has a bit of dead zone / hysterisis designed in; most pump controllers do.  If you are lucky it is adjustable.  Typically you would want the pump to shut off at about 50psi and then kick back on back around 35psi.  The accumulator is there to help absorb shocks to the system, and to keep your pump from short cycling on / off.

Remember to precharge your accumulator with an air pump prior to use.

Regards,

Frank

P.S.  I can't remember the exact numbers, but I seem to recall that fresh water is about 0.4psi per foot of column height.  So if you have to pump 10' above your pump, you loose 4psi of pressure at the other end.

[glenn kangiser]

As stated above -- get a bladder type pressure tank to keep it simple -- 50 gallon size or so should do. - maybe 20 gallons of drawdown.

Pump to water supply direct with bladder tank tee'd onto the line.  Add a check valve just before the pipe goes down to the pump-flow arrow toward the house.  Some have a hole for a pressure switch on the tank side or just put another tee on the tank side and put a pressure switch on it.  Pressure switches are usually calibrated already but are adjustable - available at most hardware stores.

Your hot hooks to one side --pump to the load side.  The switch will shut the pump off when set pressure is reached - turn it on when it drops to the low side. 

I would also suggest putting a shutoff valve between the tank and the house so if there is a break or you need to re-plumb, you can shut it off without losing your water or getting real wet.

[Redoverfarm]

Drew

Here is a look at my project from the well pump issue w/ Grundfos.


http://countryplans.com/smf/index.php?topic=3441.msg37594#msg37594

[glenn kangiser]

Grundfos makes a million pumps.  I was assuming this was a standard pressure model which should be OK to hook to a pressure system.

You get the equivalence of .433 lbs pressure per foot of head or 2.31 feet of head per lb. of pressure. 

Do you have pump pressure graphs of specs - or a model so we can look them up and static level  or pumping depth and total depth of your well?  Pressure you can build in the tank just takes away from the total possible pumping depth at the above rate. 

[Drew]

Thanks for the great information, guys.

I think the pump is the 10SQ-160.  I'm at work and my well/septic paper file is not.  However, I can check it again when I get home.

The pump is the 115v variety.  he well is 400' and the static level is 180'.  My collector will be at ground level.  If I put the pressure tank (bladder) in the proposed cabin, it might be another 5 feet up.  It's pretty level between the well and home site.

Red, I looked at your post and will go back over it again for more details.  Interesting point about the pressure tank reducing the gpm flow (energy trades, after all).  While I'm still in the planning phase about how we are going to do our water, I had been thinking about a sub-pump to collector, collector to pressure tank (via smaller pump).  I want to be able to irrigate crop fields (1/2 to perhaps 4-5 acres over time) but don't want to do it from the pressure tank.  The fields are about 80' below the top of the well, so at .38 per foot, I can get ~30 psi on gravity alone, minus line friction.  That might run my drip lines, but that's another story.

The real concern today is controlling the start and stop of the pump.  That's likely to apply to any configuration I select.  Thanks again for the know how.

Drew

PS:  I looked at some old notebooks and plans for farm projects I've had over the last three years.  The best thing that ever happened in all of them was not starting right away.  I see thousands of dollars on paper that sat, stewed, and became much cheaper, better solutions.

[glenn kangiser]

  .433 lbs per foot - but yes around 30 lbs or so --  The two tank solution can also be done but then the start and stop will be via float switches in the storage tank.  You will need another pump for pressure.  Horsepower cost requirements will workout about the same overall but equipment costs will go up and capacity of the total system will increase.  You could gravity out of the storage tank for your drip system. 

No qualms with a plastic tank, eh?  Or perhaps you are into heavy metal and would rather go galvanized?  Not razzing you too much I hope -- with you stating you were going vegetarian I though I would see how you viewed the health issues.  I don't worry about either myself.  Too many other things to worry about.



What -Me worry? 

[Redoverfarm]

  photo glenn

[glenn kangiser]

Found it looking for Newman -- thought it was better.

[Drew]

Yeah, Glenn.  The choice between leeching plastic and heavy metals is a tough one.  I was thinking of growing a bunch of cacti and giving them a big kiss whenever I needed a drink of water, but that had its drawbacks too.   Maybe I should call up my Uncle Own and Aunt Beru to see how they do it on their moisture farm

What is a meat puppet to do, right?  Maybe it's like the Snickers bar and Diet Coke for lunch.  While they don't truly cancel each other out they do minimize the aggregate evil.

And when I die, maybe I'll ask to be composted.  I should have a good start considering the level of BS I carry. 

[glenn kangiser]

Study up on diet Coke, Drew.  You'll go back to sugar.  Had any good tumors lately?

BS is good...in my opinion ... probably because I'm full of it.

[NM_Shooter]

I have to admit, I am a bit confused by a deep well pump that has a pressure switch at the pump as I don't think that would work very well (no pun intended).

Deep well pumps typically have their switches located at the accumulator.  Many wells draw down during operation, which creates an increase in head pressure.  So I think that it would be very, very tricky to set this up to work correctly.  400' of well means ~ 160psi of static pressure at the pump.

-f- 

[JRR]

Any controls in the pump would probably for motor protection and would not be useful as "process" controllers.

[Okie_Bob]

I agree with JRR. If you really have a centrifical, submersible well pump, there would not be a pressure controller built into it. I'd bet you need a seperate pressure switch located at the surface probably near the accumulator.
There, you have my 2 cents worth!
Okie Bob

[Drew]

A little clarification on what sort of controller is (or isn't) in the pump.  What I've read is that 3-wire pumps require a separate controller box while 2-wire pumps do not.

There was nothing in what I read saying that the controller function in the 2-wire pump would include a pressure switch.  That just doesn't make sense, even to me.  What it sounds like is that that functionality in the 2-wire pump is to control the starting process once power is applied.

Controller boxes, as used for 3-wire pumps, often come with float switch terminals.  I imagine that they might also have accommodations for a pressure switch signal as well.  I don't know that for sure.  What I do know (Which don't make it true, by the way) is that my 2-wire pump set-up won't have a controller box.  If that is so, how do I get the pressure switch to turn off my pump when my pressure thank is full.

I think Glenn had it when he said, "...Pressure switches are usually calibrated already but are adjustable...  Your hot hooks to one side --pump to the load side.  The switch will shut the pump off when set pressure is reached - turn it on when it drops to the low side."

[ScottA]

Sounds like this question got answered but all the replies got me confused so here goes my version. Wire the pump so that the pressure switch breaks the hot leg. Pressure switch is just that, a switch. Most pressure switches have contacts for 230v operation just ignore the extra contacts. Pipe the pump to the house. Some where on the main cold water line insert a tee with shut off valves on all 3 sides of it. From the branch of that tee insert another tee for the pressure switch followed by your pressure tank (20 gallon should do it) at the dead end. The check valve should be screwed into the top of the pump down in the well. Most well pumps come with the check valve already installed. Check this. If not, get one that goes inline with the pump. Spring check is best for this.

My concern here is with the depth of the well. I've never seen a 115v pump that would deliver any real volume of water below 100'. Your going to need something like 5gpm minimum to run you house. What's the horse power of the pump? That will tell us alot more about what it's capable of. And no a larger pressure tank won't solve a low flow problem.

FYI the controler box you're talking about contains a capacitor that kick starts the pump when it starts kinda like an A/C compressor has on it. The pressure switch still turns the pump on and off.

[Redoverfarm]

ScottA good explanation.  I did find a Grundfos makes a submersible pump to lift 525 ft that will run on 30-300VDC or 90-240VAC but a bit pricey @$1500. They call it a SQFlex pump. I believe this if I read it correctly will only be 2.2gpm @525ft.

Drew the model that you stated earlier was the exact model that I had checked on given the lift and adding a pressure tank knocked it down to .5GPM

[Willy]

Howdy folks,

I have a Grundfos submersible 2-wire well pump that works like a champ.  I plug it into my generator and it goes.  I'm trying to find a little information on the how to set it up with a pressure tank.  The tank would fill automatically and stop filling when it was full, all through the glory of the pressure switch that turns the pump on and off.

As I understand things, 3-wire pumps have a separate controller box while 2-wire pumps have the controller in the pump itself.  I've been looking for information on how to put this all together for my 2-wire pump without the controller box.

Have any of you done this before?  Do you know of a good source for information?

Gracias,

Drew

Simple solution the 2 wire pumps use electricity the same as a 3 wire pump. The 3 wire pumps are normaly used for your deeper wells that need more tork to pump water and are more efficent. The 3 wire pumps use a control box to allow a start capasitor to help get the pump going then it switches over to run. A 2 wire pump does not have a control box with a capasitor start you just run the wires straite to the pump instead. Now with both types of pumps if you use a pressure switch to control the pump you need to put it right after the power coming from the panel or generator in your case. DO NOT hook the Pressure Switch up to the red/black/yellow wires going to a 3 wire pump that come from the crontrol box!! TEE your water line coming from the pump to the pressure tank and tap the pressure switch into this TEE. Then take the power from the generator and run it thru this switch to control the power to pump. You should switch both wires to be safe even if it is 120 or 240 volts just make sure you switch(off & on) the wires instead of shorting them with the contacts inside the switch!!! Follow the directions real closely or better yet ask a electrician how or what screws are used for the incoming wires and which ones for the out going wire to the pump. Mark

[Redoverfarm]

I just like to keep beating dead horses.  When I ordered my pump for a 400 ft well it was suggested that I get the three wire and the control box(capasitor housing) because with that much depth you don't want to have to pull your pump to replace the capasitor when lightning strikes.  It is much easier to just go to the basement and replace.

I was wondering if all pumps have capasitors or not. As the model Drew was referring to is a low start-up amp(no start surge). In fact that particular model requires a lightning arrestor to be installed before the warranty is valid.

[Willy]

I just like to keep beating dead horses.  When I ordered my pump for a 400 ft well it was suggested that I get the three wire and the control box(capasitor housing) because with that much depth you don't want to have to pull your pump to replace the capasitor when lightning strikes.  It is much easier to just go to the basement and replace.

I was wondering if all pumps have capasitors or not. As the model Drew was referring to is a low start-up amp(no start surge). In fact that particular model requires a lightning arrestor to be installed before the warranty is valid.

I don't like to type a lot so I will Copy and Paste you a answer. And yes not all pumps have start capasitors. All pumps should have lightning arrestors to protect the pump motor from lightning. Here is a Franklin Pump artical explaining 2 wire and 3 wire pumps. Mark

So how does all of this relate to the motor? Well, like just about all single-phase motors, Franklin Electric submersible motors have 2 sets of windings: a run winding (also called the main winding), and a start winding (also sometimes called the auxiliary winding).

When the motor is started, both the start and main winding are energized. This confi guration, along with the start capacitor in the Control Box, provides excellent starting torque. For example, the starting torque of a 1 Hp Franklin Electric 3-wire submersible motor is 2½ times its running torque.

However, a motor has completely different electrical properties at start-up than when it is up-to-speed and running. Because of this, as the motor approaches running speed, the start capacitor and the start winding must be disconnected, and the motor operated on the runwinding alone. The timing of this is critical: Take the start winding and start capacitor out of the circuit too soon, and you sacrifice starting torque. Leave them connected for too long, and the current, or amperage, in the motor and in the capacitor will be too high for too long. So, the job of the QD Relay is to remove, or disconnect, the start capacitor and start winding as the motor reaches running speed. The QD relay does this at just the right time, so that it provides optimal motor performance, both in terms of starting and running. The QD Relay "knows" when to do this by looking at the phase difference between the incoming voltage and the current in the start winding.

To provide the absolute best performance, QD Relays are actually designed by rating. That is, a ½ Hp, 115 volt QD Relay is designed for a ½ Hp 115 volt Franklin motor, a 1 Hp 230 volt QD Relay is designed for a 1 Hp 230 volt motor, and so on.

By the way, if the control box has a run capacitor, the start capacitor or capacitors are disconnected just like the above. However, the start winding and the run capacitor(s) stay connected and working, even when the motor is at running speed. This is called a "cap start / cap run" design.

What about Franklin 2-Wire motors?

Franklin's 2-Wire motor is actually very similar to the 3-Wire motor. The difference is that the "switch" is actually located in the motor itself. In Franklin's 2-Wire motor, this component is called a "BIAC", and it also contains a triac, which switches the start winding out of the circuit at just the right time. Since a 2-Wire motor does not utilize a start capacitor, it will have less starting torque than a 3-Wire motor of the same rating. Nevertheless, starting torque on a Franklin 2-Wire motor will still be 1½ times greater than the running torque.

[NM_Shooter]

Ok...easy enough then.  Get a Square D PumpTrol or similar and install it near the accumulator.  Switch the hot leg to the pump. 

Done!

-f-

[glenn kangiser]

Great explanations, guys.

[Okie_Bob]

Glenn, I have to totally agree with you on this one. This has been a very enlightening topic and some excellent responses from guys that obviously know what they are talking about.
I would only add to NM_Shooters reply to break both legs, not just the hot side as you allude. Always better safe than sorry.
I'm also curious, Willy, do you work for Franklin? You sure seem to know alot about their products. And this brings up another point
that I believe Peg made some weeks ago---please everyone, put your location in your profile somewhere!!! It really does make it easier
to understand where you are coming from when we know where you are coming from! An example is Peg his ownself! He is from the far NW as is John and many others. Their climate, not to mention politicical environment, is much different than where I live here in E TX.
Just kinka makes everyone feel like we are on a more friendly basis.
Okie Bob
PS: I am an Okie even though I happen to live in Texas now.

[Redoverfarm]

Okie_Bob

My thoughts exactly. It sort of put's a face to the name so to speak.  I thought that when I started the post of "how's the weather" that maybe this would happen but it didn't.  A lot of the times it enters into the replies of certain topics.  I guess alot of people are afraid that if they told us where they lived we would drop in for dinner or something.

[Willy]

Glenn, I have to totally agree with you on this one. This has been a very enlightening topic and some excellent responses from guys that obviously know what they are talking about.
I would only add to NM_Shooters reply to break both legs, not just the hot side as you allude. Always better safe than sorry.
I'm also curious, Willy, do you work for Franklin? You sure seem to know alot about their products. And this brings up another point
that I believe Peg made some weeks ago---please everyone, put your location in your profile somewhere!!! It really does make it easier
to understand where you are coming from when we know where you are coming from! An example is Peg his ownself! He is from the far NW as is John and many others. Their climate, not to mention politicical environment, is much different than where I live here in E TX.
Just kinka makes everyone feel like we are on a more friendly basis.
Okie Bob
PS: I am an Okie even though I happen to live in Texas now.

Well Bob I don't work for Franklin Pumps but I have been a electrician for over 34 years and installed many pump/well system over the years. One of the reasons for breaking both legs on a pump run by a generator/extention cord you can't be sure the neutral is not the one being switched due to a incorrectly made up extention cord or cord cap terminated wrong. I will update my profile but I live in North Eastern Washington State just outside of Okanogan. PS I am a Wildland Fire Fighter now. Mark