New guy needs advice on overwhelming pump graphs for Off-Grid.

[I Drink Your Milkshake!]

Hello,
My wife andI live in Graeagle, CA and just had our well dug and now I'm trying to figure out which pump to use for our off grid property.
The well is 284' deep and the static water level is at 191' with a yield of 20 gpm.
We have an Airstream trailer on the property with septic and propane and Solar is the last utility I need to figure out. I'm trying to design it (perhaps erroneously) so the well pump will fill a 1000g holding tank which I will use to supply our trailer and also use for irrigation.
My question is which company makes a reliable submersible pump with an external controller that is solar friendly.
Thanks!

 

[Valveman]

To just fill a storage or cistern tank the Grundfos SQFlex is probably best, but also most expensive.

 

[Sponsor]

 

[I Drink Your Milkshake!]

Thanks for the reply Valveman.

I've been gathering information from this site since posting my question and I've realized there's so much to consider! 3" or 4"? Voltage? HP?
1 or 3 stage?
I was originally going with a 12/24/48v pump but they're pretty inefficient and the size of the wire I'd need was cost prohibitive. My inverter will crank out 110-220v so I'll go with a 220 instead.
Is there a difference between the 3" or 4" pump in this application?
And I've been trying to read the charts to see what HP pump I'll need based on my well numbers. I'm leaning towards a 1.5hp 4" 3-wire submersible.
We're building a small 1200 square foot home with one bedroom and minimal irrigation and I'd like to make sure I'm putting in a system that won't need to be upgraded when the time comes to move in.
Does this add up or am I missing something?

 

[Valveman]

You will be pumping from at least 191' and possibly as much as 280' deep. I would pick a pump that would work from 250' or so. The 3" SQ pump has the 5 second soft start, which makes it easier on generators and inverters. The 5SQ05-180 would be the one I would pick. But this system is just to fill the cistern and will not make pressure for the house. You can use another of the same kind of pump in the cistern to pump water and pressure to the house.

 

[Valveman]

The pump in the cistern only needs to be able to produce 115' of head, which is the same as 50 PSI for the house. The same 1/2HP motor can pump more water by using a 10 GPM pump instead of the 5 GPM like in the well. So, in the cistern I would use the 10SQ05-160.

 

[Valveman]

The two pump system would look like this.

 

[Fitter30]

How far will the storage tank from well head. 10 gpmx10 a day = 6000 gallons
People use 100- 125 gallons per person per day. The storage tank the height of the tank and diameter. Unless your using a jet pump to supply the house the useable might be 7-800 gallons. Submersible water would have to be over top of the pump at least over the motor but check with the pump company or.manufacturer.

 

[Reach4]

How far will the storage tank from well head. 10 gpmx10 a day = 6000 gallons
People use 100- 125 gallons per person per day. The storage tank the height of the tank and diameter. Unless your using a jet pump to supply the house the useable might be 7-800 gallons. Submersible water would have to be over top of the pump at least over the motor but check with the pump company or.manufacturer.

Submersible in the tank would normally be horizontal inside of a flow inducer, so the water will draw down farther than if the pump was vertical.

If the pump was vertical in a flow inducer, the water still might pull down low, if there was a waterproof seal at the top of the flow inducer. Not sure if that is advisable to rely on that.

 

[Valveman]

 

[I Drink Your Milkshake!]

Good morning,
Thanks everyone for all the info on pumps, cisterns and the design drawings. I really appreciate the time spent on educating me thru this.
The only valves I deal with are when I'm putting an IV in one of my patients.

Fitter30- To answer your question the cistern will be within 15' of the well head. You think I need a bigger cistern?

I'm thinking about making two different systems that I'll feed from the well.
While we build the 2 bedroom house my wife and I will be living in the Airstream on the property. There will be minimal water use with no clothes washer or dishwasher, just two sinks and a shower and toilet. I was thinking the 1000g cistern would be our supply with a pump in the cistern (good suggestion Cary!) or perhaps a boost pump in the pump house.
Once the house is finished I could divert the water to a pressure tank that would supply our needs for the home and when needed fill the cistern. We're going to keep the Airstream hooked up on the property to periodically rent out to a Travel nurse or vacation rentals.

My question is: Will the 5SQ05-180 be ideal for filling the house pressure tank?
I did my research on the 5 second soft start (another good idea), does that pump require a torque arrestor?

Thanks again.
Mat & Christina

 

[Valveman]

I gave you two curves and two model numbers. You will need the 5SQ05 in the well because it is so deep. But you need the 10SQ05 in the cistern because it is not deep. The cistern pump will not be filling the house pressure tank, it will be supplying water to the house at 50 PSI. With the CSV the pressure tank only fills when you stop using water in the house. Water comes from the pump, not the pressure tank.

Also, with a CSV you do not need a torque arrestor as the pump will not just be cycling on and off repeatedly. Even without a CSV a torque arrestor is just another possibility of getting the pump stuck in the hole.

 

[Bannerman]

While a cistern makes sense when a well has a low recovery rate, but since your well has a 20 GPM recovery rate, it is more than capable of supplying all of the water requirements for several homes.

A cistern will complicate matters as it not only requires an additional pump, but also periodic routine maintenance for cleaning and disinfection, not to mention expense and space considerations.

 

[Valveman]

Yeah with a good well you really don't need a cistern. But you will need a larger well pump to lift from that depth and build the 50 PSI the house needs. Instead of two 1/2HP pump to do the job, a 1HP in the well would do it all.

 

[I Drink Your Milkshake!]

While a cistern makes sense when a well has a low recovery rate, but since your well has a 20 GPM recovery rate, it is more than capable of supplying all of the water requirements for several homes.

A cistern will complicate matters as it not only requires an additional pump, but also periodic routine maintenance for cleaning and disinfection, not to mention expense and space considerations.

I don't know why I assumed I needed a cistern. Perhaps because I see some of the neighbors have them? I asked a guy down the road and he said his wells replenish rate was 5gpm so that makes sense.

OK, last question.. and it's about the much debated check valves. (I've read your posts Cary and your minimalist view on them does make sense to me.)
But since this is a pretty deep well, won't the weight of the water in the pipe force itself back down thru the pump? Or will the single check valve built into the pump itself be able to handle this pressure? Forgive my ignorance, I'm still learning about all this.
Thanks!

 

[Bannerman]

will the single check valve built into the pump itself be able to handle this pressure?

The check valve within most submersible pumps will be robust enough, but if you want to include a 2nd check valve for redundancy, obtain a quality spring loaded CV, and thread that directly onto the discharge fitting of the pump.

 

[I Drink Your Milkshake!]

Thanks Bannerman.
Sorry. I guess I lied about "One last question"

I've seen videos of people lowering pumps down on a rope and others using the poly pipe.
I feel like a rope would be good insurance.. or does my depth preclude that option.

I'd like to add a frost free hydrant or two on the property between the pump and the Airstream and possible an outdoor shower.
Is there a link or site you guys would recommend where I can do some research on others that have gone this route?

 

[I Drink Your Milkshake!]

7 months later..

Spring is finally here up in the Sierras! The snow has melted and it's time to start working on the well pump.

I'm still leaning towards using a 2500g cistern and filling it with the well because we're off-grid and energy usage is a concern. Using one pump strong enough to supply the house as well as the Airstream will require twice the amperage than using the 10SQ to supply the house and periodically using the Firman 7500w generator to supply the 5SQ for the cistern.

Anyone else have a similar solar scenario that's worked for them that can verify this approach?

Valveman, you mentioned using the 5SQ05-180 for the well. The Grundfos System Sizing Matrix rates it effective up to 177'. At the worst case scenario we will be pulling from 250' so shouldn't I go with the 5SQ05-170 in this case? Or am I reading that chart incorrectly?

Again, thanks for any guidance in these matters. This is way out of my wheelhouse and I really appreciate any feedback.

 

[Bannerman]

Using one pump strong enough to supply the house as well as the Airstream will require twice the amperage than using the 10SQ to supply the house

By utilizing a cistern, the same water will need to be pumped 2X.

A pump consumes the most energy when working hardest, which is when it is supplying water at the highest flow rate it is capable of pumping.

In filling a cistern, although a smaller pump may be utilized, it will operate for a long time period to refill the cistern. Because the well pump will not need to build much pressure, and because there will be minimal restriction to flow, the pump will be supplying water to the cistern at its maximum flow capacity and therefore, will be consuming the most amount of electricity for the entire time it is operating to refill the cistern.

For example, if a 2500 cistern is configured to refill when 2000 gallons has been consumed, a 10 GPM pump will need to operate for 200 minutes (3.33 hrs) continuous to replace the 2000 gallons consumed each time.

If that 1/2HP pump draws 5.2 amps/hr @230 volts (= 1,196 watts/hr), then it will consume 3,943 watts (3.95 KW) to refill the cistern with 2000 gallons.

The pump supplying water from the cistern to home fixtures will consume additional electricity at a significantly lower consumption rate than the well pump since it will build pressure which will reduce it's delivery and consumption rate, and it will typically consume power only when water is being utilized in the home/Airstream.

While a 1HP well pump normally consume a greater amount of electricity than the 1/2HP well pump when both operate in an identical manner, without a cistern, the well pump will build pressure which will reduce its pumping load, and the well pump will only operate while water is actually being consumed (similar operation frequency and duration to the smaller cistern pump mentioned above).

When utilizing a CSV, a 1 HP pump will consume significantly less power (often 50% of the maximum consumption rate) since the pump flow rate will not normally be maximized, but will be reduced to equal the actual water usage flow rate. For instance, if a 1HP pump draws 11.2 amps @ 230 volts (2,576 watts) while pumping at its maximum delivery rate, depending on the pump, it may consume only 1,288 watts for much of the time it is operating while water is being actually being utilized at a significantly lower flow rate than the pump is capable of supplying.

 

[Reach4]

When utilizing a CSV, a 1 HP pump will consume significantly less power

Less power but more energy.

 

[Valveman]

Good stuff guys! Main thing to remember is that any pump will produce more gallons per Kw when operated at or close to it best efficiency point. Restricting flow with a CSV or slowing with a VFD can reduce running amperage by 50% or so, but also increases the Kw needed to pump a certain number of gallons.

I don't see a 170 available in the 5SQ05. The 140 won't go deep enough so the 180 would need to be used in the well because of the depth. But I would use a 10SG05-160 in the cistern as it will pump twice the amount of water with the same 1/2HP because it is only needed to work between 40 and 60 PSI.

This set up lets you use water from the cistern or directly from the well.