Substitute for Grundfos CU IO-101

DesertDweller · June 2021

I'm about to connect my Grundfos SQ Flex 11 well pump to my solar system, but I'd like to incorporate a way to switch from my DC solar array to being powered by AC or my backup generator. The Grundfos CU IO-101 does just that but is very pricey!

Grundfos IO-101-230V SQFlex Pump Controller

https://www.solar-electric.com/grundfos-io-101-230v-pump-controller.html

I'm thinking of putting in a DC circuit breaker to shutoff power from panels. But then, how can I easily plug into my AC power source?

Midnite Solar MNEPV 150 Volts 15 Amps DC Circuit Breaker spanMNEPV-15span

I have everything wired into the CU-200 control box:

Should I just disconnect wires going to solar and then connect a power cord with pigtail?

Dave Angelini · June 2021

You have to be careful with this as you are putting a price on not using the correct method Grundfos wants you to do for this.

The price is water and the loss of your well pump! The pump will run off 90 to 240vac! You have to make sure you do not damage the existing electronics or the pump. I would not tell a client to do this BTW.

I certainly would not do this now, summer in the desert?
If you bought the pump from the store here you can ask them on Monday!

I would wait unless there is some pressing reason, especially if you are offgrid!

wellbuilt · June 2021

Well , I tend to hang on every morsel of information dave gives me .

But in this case I may have some thing to add .
I had the same question , I wanted to pump water with the sun power , but I don’t have good sun year round so
I have to be able to power the pump off my genarator .

What I’ve decided to do is just add 4500 watts of solar panels to my inverter battery system.

Then I can pump water into holding tanks in the after noon when my charging system is in float , I have limited water in my well so I want to pump slowly .
I want a timer that will run 10 mins on 11/2 hours off 3 times a day for 180 gallons of water .
my pump puts out 6 gallons a minute . But at 120 volts I don’t really know how much water I’m going to get @ 700 feet.

In the winter when there is no sun I can just run the pump thru the inverter while I’m charging and the generator will power the pump thru the inverter pass thru as a regular load .

I ran this buy the tech guys at AWS and they said it will work .

mike95490 · June 2021

> But at 120 volts I don’t really know how much water I’m going to get @ 700 feet.

There should be a pump rating curve chart, that tells you GPM vs Lift ( sample attached )

regarding a timer, Starting Cycles is a large factor in pump life, which is why some folks stack several pressure tanks to help reduce the pump cycles.

Image: https://us.v-cdn.net/6024911/uploads/editor/et/mp1hh46tlh0i.jpg

wellbuilt · June 2021

Hi mike, from what I under stand , my chart tells me I should get 41/2 to51/2 gallons a min depending on the height of the water in the well .

In the spring I can see the water in the pipe , now the water is down 300 feet by September in down to 500 feet
my well is 41/2 “ so 3/4s of a gallon a foot .

I think most of the year I could just pump and fill my tank , 200 gallons or so
In the fall when the water is low if i draw the well down to far we get a red mud drawn down into the well
This mud fills the veins in the rock and chokes off the supply so I just don’t know how all this is going to play out .
A lot of the wells only get 1or 2 gallons a min ☹️

Dave Angelini · June 2021

So by not using the grundfos controller, you have to limit the time as you can't limit the flow without the controller.

You definately do not want solids in the pump, for very long! A timer or manual shutdown. Pool timers do use some electricity 24/7 and I like a spring wound hour timer for attended operation. You wind it to the hours you want and it shuts down by itself. You have to do this daily or?, but it is foolproof, inexpensive and easy. I do this all of the time with solar domestic hot water. Most offgrid people are there at the house and do not need controllers to be complicated.

Whatever you do, make sure there is an SPD for anything connected to the grundfos controller. Most of the people who need a new controller probably got hit. A generator out in the woods or mountains is a nice target down to a $3K pump.

wellbuilt · June 2021

It’s not like I don’t want to buy a cu200
I just don’t want it to fill my tank and pump water till it’s full .

I’m trying to control the amount of water I pump at one time
10 minpump time drops my well 50 feet .

My well guy tells me this is acceptable ?

What can a cu200 do for me ? Is there a good reason to use on ?

JRHill · July 2021

2008.
When I first tackled our project the water was the first item to address. It didn't make much sense to do much planning for anything until I knew we had water. I contacted the local well company and the owner came out to do a site review. The first thing he asked was "OK, where do you want it?" I tried to get his input as to the best location and he wouldn't touch on an answer (I know why). We walked over to a place that was adjacent to a shallow draw and I said "Here." He knew we didn't have grid access and asked how we would power the pump. Of course solar and with a way to power with a generator too. I had never heard of Grundfos. In a few weeks he came back with a quote that blew my socks off. The quote showed all the well column details per foot but the pump and equipment was just wild. I gave the go ahead for the drilling and setting the pump and we'd deal with the rest next year as the rainy season was coming on and he was concerned for getting his rig out when rain/snow happened. His quote was for the 11SQF. His company didn't do too much with off grid stuff so he relied on his Grundfos rep to spec it.

So I researched the Grundfos equipment and was really impressed. But the prices quoted for everything Grundfos were well over list prices. When I asked questions he had to get back to me as he was completely relying on a sales engineer from a supplier and not familiar with the solar DC system details. I did pay for the setting of the pump and his phenomenal markup but built out the rest myself the next year. I started with:
- 11SQF
- 80g pressure tank
- Pressure switch
- CU200
- CU101
- Homemade mast (recycled well column)
- 3 195w panels 1x3
- MorningStar 8a controller
- 4 12v RV batteries for a 48vdc system

All in a 4x8' pit under the frost line, 5' deep. It worked great for years and years. Later the owner of the well company forgave me for finishing the system myself. So this is the basic background - now your question.

Current water well:
- 11SQF (Same pump)
- 2ea 80g pressure tanks
- Bypassed CU200
- CU101 in service always on
- Mast, 4 panels wired 2x2
- Morningstar 15a (8a was obsolete)
- 8 6v Trojan golf cart batteries

The CU200? Not needed. Oh, its cool with the LEDs and all. And the communication from the well pump for error codes? That's cool but not a primary function. Sometimes false errors/shut downs/manual resets. At an earlier time when the Morningstar 8a controller died and was obsolete I dove deeper. I bypassed the CU200. I used the pressure switch on the tank to power the pump cycles instead of the CU200, switching the mains to the pump instead of the CU200 internal relay. I still always used the CU101 as I could just leave it "ON" and if I plugged in 120vac it made no difference. Actually the 120vac delivers more GPM than at 48vdc, using a few more watts with more water delivery.

So now, 2021. The water well Trojan GC batteries are at end of life. I'm not going to replace them. Instead I am just going to connect the CU101 directly to the house system which has 4 3.8 SimpliPHIs. I don't need separate systems for the well and house anymore for risk avoidance.

Sometimes we can overly complicate things. For the water I did that but it was a waste of money.

I have a CU200 for sale. Any takers?

JRHill · July 2021

BTW, I didn't answer the OP question to a CU101 substitute. I don't know of one. Yeah the device is pricy. But it's so easy to hook-up and extremely reliable.

In the OFF position the pump circuit is completely down for maintenance like pressure tank adjustment (which is the only thing I ever have to do).

In the ON position and on solar it's a pass through. If ON and AC applied the DC input is disconnected (safely) via an electrical mechanical relay. It has a very minor transient draw.

So there's the input. Sure, you could do the same with a transfer switch but you'd better have it right lest AC get into the DC circuit. And if an AC power problem it falls back to DC with no user action. I could have 4' of snow over the well pit lid. It's nice to be able to leave it ON and either plug it in or not.

wellbuilt · July 2021

Thank for the reply jr good information

Substitute for Grundfos CU IO-101

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