Solar driven deep well pump

jvcyclist

Hey folks: I come with a question. Ok, I have a deep well pump which I only want to use when it is sunny...way too much load on the batteries to use it at night. We have had a flop float sort of deal to control the level and on examination, it never lets our 600 gallon tank fill...and often lets it down to like 80 gallons before it triggers. We tried shortening it...and that just kept it from filling even moreso.

So, I have a neat little float switch which will set us up so the tank fills to the top and the pump is enabled when we use it down just a few gallons. That works fine for our purposes...we'll never work on the bottom half of the tank.

Now, the switch and wiring are pretty light-duty. The old flop switch worked off one leg of the 240 (so was 120) and it works fine because I have a Coyote pump protector...it won't let the pump see the 120 when the other leg (controlled by the flop thing) is off. I think I'll still use the 120 leg for control the pump, but...

Given the light duty of the float valve, I am assuming I need a relay...and so I put, say, 12 volts on the float valve and when it makes contact, that trips the relay, switches on the 120 leg and the pump runs. First question: Where does one get a relay like this? I am without a clue.

Second question. To generate the 12 volts and kind of be an elegant way to control the well pump (which I ONLY want to run when the sun is out) I am thinking of using a small 12 volt panel (which I have) to energize that side of the relay. So the logic would be, the sun shines...the 12 volt circuit is hot...and if the tank is down enough for the float valve to make contact...that fires the relay and the pump kicks on. Conversely, if it is night, or there isn't a lot of sun out, no power on the low voltage side and even if the tank drains down a bit, nothing happens until the sun comes out.

Is that elegant? Or am I overthinking it? The only other way to get 12 volts there would be a transformer or, I guess, a battery...which seems less elegant.

So...what do you think? And if some expert could point me at a relay (or THE relay) for this job, I'd really appreciate it!

Jim

mike95490

Re: Solar driven deep well pump

I used one leg of my 240, to drive the float switch, which is wired to the CONTACTOR which controls the pump.

Contactors are like Heavy Duty relays for larger motors.

TnAndy

Re: Solar driven deep well pump

You can get those contactors at about any decent electrical supply place.

jvcyclist

Re: Solar driven deep well pump

Contactor! Tha's what I need for sure. I even found a 2 minute video on how it works! Thank you so very much!! Now, anyone like the idea of driving the contactor with a small solar panel? Anyone hate it?

Jim

SteveK

Re: Solar driven deep well pump

The problem I see is short cycling. On some days you may get constant on-off relay action. Probably not good to cycle them this way I'm guessing? You could clamp it but then the relay would stay engaged until the float switch broke the circuit, all the while running on less than "properly sunny" hours. what ever that may be...

Maybe a contactor offering with some sort of built-in hysteresis?

jvcyclist

Re: Solar driven deep well pump

SteveK wrote: »

The problem I see is short cycling. On some days you may get constant on-off relay action. Probably not good to cycle them this way I'm guessing? You could clamp it but then the relay would stay engaged until the float switch broke the circuit, all the while running on less than "properly sunny" hours. what ever that may be...

Maybe a contactor offering with some sort of built-in hysteresis?

Great point...and one I missed. Of course, I live in New Mexico so there aren't many days that I'd get that on-off cycle, but a good point non-the-less. And hell, I just got introduced to contactors...and now I gotta find one with built-in hysteresis?? :-)

Thanks for the comment. My plan ain't dead yet, but it is wounded and staggering...

Jim

TnAndy

Re: Solar driven deep well pump

I'm sorta curious about the pump, and it's supply. Is this one of those Gundfos SQ series pumps that runs on AC or DC ? I'm guessing not, since you only mentioned 240 to the pump.

How do you have the power supplied to the pump that the panels have to build to a certain point of output to run it? Just curious, because I have a well I plan to do this on ( using the Grunfos on DC, and about 3-400w of panels to just run it when sun hits the panels, and let it fill a storage tank )

On the contactor, probably cheaper and less trouble to forget the small 12v panel for it, and use a transfomer, power from the transformer always on the float switch contacts, which are Normally Open.

When the water level falls, they close, engaging the contactor, and the power to the pump IF the panels are producing.....and if they aren't producing, like the middle of the night, then nothing happens. Your only loss would be a small amount for the contactor coil, and the transformer. IF that bothers you, connect a photo cell before the transformer and nothing powers up until daylight. You can probably find an adjustable photo cell so it won't let power flow until good sunlight, or shade the cell "eye" somehow to make it do what you want.

SteveK

Re: Solar driven deep well pump

jvcyclist wrote: »

Great point...and one I missed. Of course, I live in New Mexico so there aren't many days that I'd get that on-off cycle, but a good point non-the-less. And hell, I just got introduced to contactors...and now I gotta find one with built-in hysteresis?? :-)

Thanks for the comment. My plan ain't dead yet, but it is wounded and staggering...

Jim

Heh, well I'm sure one could rig a multivibrator out of 555 timers or op amps to provide the hysteresis, only timing out if the levels of the small panel reached a certain setpoint value stood up by a resistor network.....I'm dating myself here, lol....

But now knowing you are in NM, with favorable conditions most every day, I think a simple store bought timer is the way to go. I mean, how many days do you really need to compensate for that aren't near perfection to begin with?

techntrek

Re: Solar driven deep well pump

I was going to suggest a timer, too. Set it to be ON 9 am to 3 pm and forget it. You could go for a longer duration over the summer but then you would have to remember to change it twice a year. No point with such a large water reserve, just take advantage of the optimal 6-hour window and rely on the reserve the rest of the time.

jvcyclist

Re: Solar driven deep well pump

TnAndy wrote: »

I'm sorta curious about the pump, and it's supply. Is this one of those Gundfos SQ series pumps that runs on AC or DC ? I'm guessing not, since you only mentioned 240 to the pump.

How do you have the power supplied to the pump that the panels have to build to a certain point of output to run it? Just curious, because I have a well I plan to do this on ( using the Grunfos on DC, and about 3-400w of panels to just run it when sun hits the panels, and let it fill a storage tank )

On the contactor, probably cheaper and less trouble to forget the small 12v panel for it, and use a transfomer, power from the transformer always on the float switch contacts, which are Normally Open.

When the water level falls, they close, engaging the contactor, and the power to the pump IF the panels are producing.....and if they aren't producing, like the middle of the night, then nothing happens. Your only loss would be a small amount for the contactor coil, and the transformer. IF that bothers you, connect a photo cell before the transformer and nothing powers up until daylight. You can probably find an adjustable photo cell so it won't let power flow until good sunlight, or shade the cell "eye" somehow to make it do what you want.

I'm sorry...in the interest of brevity I did a bad job of describing my pump. We had some real yahoos out here install the pump and it is just a regular old pump motor (3/4 horse, if memory serves). We started using it by running a propane generator, and when we finally had the house system in and running, we just hooked up to that (240 AC). Since the pump pulls around 3.5KW, it is sort of hard on the batteries when it is running at night. During the day? No problem, obviously. Now, when the pump finally fails, I am absolutely going to put in a Grundfos for a lot of reasons, but I'll just keep the 240 connection running.

To the other suggesters...absolutely I have been planning on a timer, but once again, being a naif with respect to electric stuff, I can't figure how to run the timer (since I can only find timers that NEED the 120 running to it to time...since I have a float switch...ya see the issue?)...I guess I can put the timer on the OTHER 120 leg and use it to control that side of the circuit...so ok, here is what I understand the suggestions to give me:

1. I get a contactor (thanks for that!). Probably single pole, run one 120 leg through that (so split the neutral and run that and one leg of the 240 to it). Hook the 24 volt circuit up to a transformer driven by a 120 volt outlet (got it). When the float drops down enought to throw the reed in the thing, the 24 volt circuit makes, fires the contactor and that 120 volt leg becomes hot to the Coyote pump controller.

2. Put a timer on the OTHER 120 volt leg (hell, already GOT the timer). So I am running a neutral and a 120 through that to keep it on...and from 9A until 3P, it is on and hot to the Coyote pump controller.


And when it is 9A...and until 3P...the float valve will control the pump...because both 120 legs will be hot when the water level goes down. Since I have a 600 gallon tank, which will be full (or nearly so) at the end of the day, having no power to the pump won't be a problem.

Make sense? Any further suggestions? How much power is that transformer gonna pull 24/7?

Jim

solar_dave

Re: Solar driven deep well pump

I had a clock timer that was a 240V DPST that runs my pool pump, it was rated for 2HP at least.

Here is just one I found on line
http://www.smarthome.com/48785/Intermatic-T104R3-DPST-Pool-Spa-Time-Switch-in-Metal-Enclosure/p.aspx

jvcyclist

Re: Solar driven deep well pump

solar_dave wrote: »

I had a clock timer that was a 240V DPST that runs my pool pump, it was rated for 2HP at least.

Here is just one I found on line
http://www.smarthome.com/48785/Intermatic-T104R3-DPST-Pool-Spa-Time-Switch-in-Metal-Enclosure/p.aspx

Dave: Doesn't the fact that one of the legs of the 240 is off (when the float is at the top and open) mess up the function of the timer? That's been my whole thing with the timer...If you interrupt the power to 'em, they don't time, right?

And I've not been able to find a timer that runs separate to the power that it controls. Although I might have a plan now with one leg interrupted by the float and one leg interrupted by the timer.

Jim

TnAndy

Re: Solar driven deep well pump

Check water sprinkler timers.....lot of them run on 24v.

mike95490

Re: Solar driven deep well pump

Standard Intermatic Timer, is what I use. It switches the coil for the contactor, and is in series with the float switch.
from my .sig:
Grundfos 10 SO5-9 with 3 wire Franklin motor (1/2hp 240V 1ph # 214505 ) on a timer for 3 hr noontime run - Runs off PV

It's a 120 V timer, so I just wired it to one leg of the 240 for the pump ( I have a common neutral at the pump for a 120V outlet )

solar_dave

Re: Solar driven deep well pump

jvcyclist wrote: »

Dave: Doesn't the fact that one of the legs of the 240 is off (when the float is at the top and open) mess up the function of the timer? That's been my whole thing with the timer...If you interrupt the power to 'em, they don't time, right?

And I've not been able to find a timer that runs separate to the power that it controls. Although I might have a plan now with one leg interrupted by the float and one leg interrupted by the timer.

Jim

So you get a DPST timer for the 240 AC and a contactor for the float valve. Contactor is only energized when timer is in on cycle. Some lower voltage drives the contactor if the float switch is in the make position, like one leg of the AC.

jvcyclist

Re: Solar driven deep well pump

Thanks all...the light just came on!

Dave, especially. That works.

Jim

solar_dave

Re: Solar driven deep well pump

jvcyclist wrote: »

Thanks all...the light just came on!

Dave, especially. That works.

Jim

No Problem, any time.

techntrek

Re: Solar driven deep well pump

To further what solar dave said, look at water heater timers. Timer runs from 240, output will then drive the contactor, and it can handle far more amps than the water pump needs so no worries about welding the contacts.