Controlling a well pump with a pressure switch, or other options.

[coloradobound]

I'm working on trying to decide how to operate a pump for a well to supply a raw water tank a distance away from the well. Radio telemetry, etc will not work due to terrain/distance. Is there a way to use a pressure switch (on the basis of pressure differences in the pipeline for varying depths of water in the tank) to tell the pump when to turn and off? Any help would be appreciated. I dont think this is very hard, just having a hard time finding information on various equipment/electronics needed.

Thanks.

 

[semo]

While I've seen what you propose many times it is not the most desirable control.

Yes, you can use a pressure switch near the well to control the on/off status of the well. You will have to bear in mind that the pressure switch will not only see the static head (which is what you really only want to see); but, also the dynamic head on the pump during the pump run cycle. Then during the pump off cycle if there is no flow through the line it will see the static head. Your switch must have a high enough differential to account for this. You can also use a pressure transducer in lieu of the switch for high differential conditions.

There are other means of communication besides radio telemetry. Cell phone systems are in use as well as direct telephone lines. Many have been discussed in other threads on this forum.

 

[krb]

Are you using a bladder tank for storage? If so, then it fairly easy to use a pressure switch in conjunction withthe tank to turn the pump on and off bases on the dirrerential in the tank. Many residential wells use this sort of arrangement. I think there is some info onthe goulds pumps website.

 

[coloradobound]

It is for a small residential development. The well is around 3000 feet deep and pumping about 24 GPM. It is a ground level steel tank. I was told about a control type called Gronel Remote Tank Level Controller. Has anyone heard of this? I tried searching the name but no luck.

And thanks for the responses. Depending on the actual distance we may end up actually going with a line laid along the supply line.

 

[schmilton]

If you have a separate outlet and inlet, you could use an altitude valve or float controlled valve at the tank. This valve would close as the tank fills. When the tank is full, the valve should close and the pump will dead head. A pressure sensor at the well could detect this condition and stop the pump. As the tank is emptied the valve would open. A timer could be used to start the pump. The time between starts would have to be adjusted depending on usage. This would provide fairly coarse control, but would not require communication between the tank and pump sites.

 

[BobPE]

By ground level storage tank, do you mean that the system gradient floats off the tank, or do you have a seperate pumping system that moves water out of the tank to the system? If it is the former, where the gradient floats off the tank, avoid altitude valves and just go with a simple pressure switch, calibrated to the overflow level of the tank. To calibrate, set the switch from visible observations made while operating as to when the tank is overflowing. Set the switch just below the point where the tank overflows. This is a simple system, but then, you have a simple system, no need to complicate it. Locate the pressure switch somewhere convient, like near the pump. The pressure conditions at the swithc may vary slightly, as previously discussed in other posts, but it will be no big deal as you will get great resolution as to the level in the tank from the pressure switch along the operating range of the pump you are using.

let us know how you make out...

BobPE

 

[coloradobound]

The system is actually set up in the pump in the well supplies the raw water tank, then the raw water is filtered via a reverse osmosis system, then distributed. Still looking into the distance between the well and the tank to see if a cable is feasible or to find more information on a control system near the wellhead.

 

[BobPE]

coloradobound:

The well most likely then floats off the tank...a simple pressure switch solution would work great. Check to see if there is an altitude valve though....I wouldn't use a cable...the level difference between the static level you see at the tank and the dynamic pressure you see at the pump is not going to be a big problem to deal with and account for through your calibration of the pressure switch.

BobPE

 

[coloradobound]

None of this is actually built yet, it's still in the design phases.

 

[BobPE]

YIKES....excse me for falling into the trap I so often warn others about....assumptions...

If you are designing it, it is even easier. Talk with some of your engineers that have done this before and you should have no problem...

take care...

 

[coloradobound]

Hope I didn't come across badly on that last post, if I did, I didn't mean to. Yeah, we basically have the option of looking at all angles of it right now. And its nice having a forum like this to get others experiences and knowledge on these subjects. Just trying to find the most cost effective and yet reliable option for running the pump. We are all discussing it on what would be the best route to take and just haven't dealt with this situation very much yet.

 

[BobPE]

colorado: No way did you come across badly....I was more angry with myself since I assumed things....The key to this place is not to assume anything and to ask questions until you get enough data to try and help.....

You are at the right place to get ideas and just bounce things off people without sounding funny or worrying what people will think!!!!

I have put in many control systems for well water, and I have found the pressure switch to be cheap, and more importantly, easy to repair when you leave your designs behind for others to fix and you, the engineer, are long gone. Pressure switches are not always the correct answer, but you will know when that is the case. For your case, being raw water with no demand, your system should be relatively stable and you will be able to reliably relate pressure to tank level....

take care...

BobPE

 

[semo]

I think Bob said a mouth full right there. I've done the same thing many times. Or not get detailed enough, or get too detailed, etc.

Any local electrician and many operators can replace a pressure switch. The more sophisticated systems also require more sophisticated (did I spell that right) repairmen.

As long as there is no other discharges from the main, your switch should only see the water level in the tank. Keep the switch in a freeze proof location or use an oil reservoir device to transfer the pressure.

I also agree with staying away from the altitude valve. You are only asking for additional maintenance that's not needed.

 

[hydrae]

Coloradobound
If this system is not built yet, a couduit laid next to the pipe to a float switch or two at the top of the tank will remove any error that a pressure switch will see. You can get wire any length you want. Pull a few extra wires in the couduit for any future improvements the operator may want to do in the future. To repeat Semo, 'Any local electrician and many operators can replace a pressure switch.' They can also replace a wire in a conduit or a float switch.

Hydrae