Author Topic: Pump options for an off-grid, cistern only rain water collection  (Read 697 times)

tx2utila

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Building a home in a remote area which will be solar, and rain water collection.

Many of the homes in the area have cisterns which are piped from underneath then come up to the pump, then pressure tank, then to the house. No one has heard of CSV so we will be the first to try it. Our cistern will hold about 19k gallons. The Cistern is the first floor, the second floor is bedrooms with 2 baths, third floor is living area, kitchen and a bath. Each floor is 9 feet. Total height of the home is 38 feet to the top of the roof.

Fear of a leak made me decide to build the cistern as one piece, with access from above, there are two 2" pipes to feed the pump. The other problem is there is a divider wall in the cistern with a leveling window at 7 feet. Both sides will be feed by rain collection. The drawback is making sure my pump can bring the water up and over the cistern to fill the pressure tank and then the house while not killing my solar system or pump. That is why I am interested in the CSV. Most of the homes use Jet pumps.

What are my best options: Jet pump vs Submersible (Hallmark)? Now for the twist, I have to be able to pump out of both tanks, a Jet pump could do that, but I would need two Hallmarks, and thus would I need two CSVs? I'm visual so illustrations or pictures work best.

Attached is the top of the cistern with the two 2" pipes, the divider wall is between them.
 

Thanks, Brad


Cary Austin

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Re: Pump options for an off-grid, cistern only rain water collection
« Reply #1 on: August 11, 2020, 06:56:21 AM »
Jet pumps work fine with a Cycle Stop Valve.  However, it will be tough to draw from 2 suction lines.  Maybe you could just put a little sump pump in the other cistern and pump water to the cistern with the pump or foot valve when needed?  The Hallmark submersible would also work, but the inexpensive 33 GPM version is a 1HP and would require more battery power to start.  The best pump for running on generators or solar is probably the Grundfos SQ, as it has a 5 second soft start built in.  Something like a 10SQ07-240 would work, and would draw half as much energy as a jet pump or other brand of submersible.


tx2utila

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Re: Pump options for an off-grid, cistern only rain water collection
« Reply #2 on: August 11, 2020, 08:23:57 AM »
Thanks, I saw that illustration in a previous post from 2009 and thought that might be what I have to do with the way the cistern was built. The next cistern may be built differently.

Thanks for the suggestion.

Brad

tx2utila

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Re: Pump options for an off-grid, cistern only rain water collection
« Reply #3 on: August 12, 2020, 06:00:33 PM »
Hi Cary,

Another question regarding the low yield pump illustration. So with my tank being separated I would use a sump pump to move water from one tank to the other tank which has the Grundfos pump to supply the house. Most sump pumps work opposite of what I'm trying to do which is move water from a full tank to a half full tank. Do you have recommendations on float system and pump that work that way?

Thanks, Brad

Cary Austin

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Re: Pump options for an off-grid, cistern only rain water collection
« Reply #4 on: August 13, 2020, 07:04:19 AM »
Leave the pump down float switch on the sump pump, so if it pumps that tank dry it will shut off.  Then loop the wires through another "pump up" float switch in the tank you want to fill.

tx2utila

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Re: Pump options for an off-grid, cistern only rain water collection
« Reply #5 on: August 16, 2020, 11:23:25 AM »
Good morning,

Couple of more questions:

If I order the Pside-kick set it comes with the pressure switch set to 40-60, I'm looking at getting a Gould J10S pump, but all of the pumps I've looked at already have a pressure switch installed and it is set to 30-50. Would the 30-50 still deliver a consistent 50psi or would it then be 40 because of the CSV?
Do I adjust the preinstalled switch to match what your kit has? Or bypass that switch and just use yours? I thought I remember seeing something about the PS has to be mounted after the CSV?
Also, the builders in our area install these sediment traps to help with the filter system, should that go on before the sidekick set up or after? Attached is a picture of one of the set ups they do.

Also, is the only difference between the 4.5 gallon and 10 gallon, the amount of water available before a cycle of the pump? So you might get 1 or two toilet flushes extra? And the pump might run an extra 10 or 20 seconds to fill the tank after the water is stopped but you would still be well within the recommended 2 minutes, correct? Is there any other advantage to the 10?

Thanks, Brad

Cary Austin

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Re: Pump options for an off-grid, cistern only rain water collection
« Reply #6 on: August 17, 2020, 07:21:45 AM »
The J10S can build 74 PSI max, so it works fine with a 40/60 switch.  Yes you would wire around the existing switch on the motor and use the 40/60 switch that comes with the PK1A kit as shown in our wiring diagram under "jet pumps".

4.5 gallon tank holds 1 gallon of water, and the 10 gallon tank holds 2 gallons. You don't need the 1 minute or 2 minute recommended run time when using the CSV, as the CSV will not let the pump cycle at all when using water.  The low amp draw caused by the CSV when filling the tank also reduces the motor heat and it no longer requires a full minute of run time to dissipate the heat.  But the 10 gallon tank does make the pump stay on longer, which is a mechanical timer to make sure you are finished using water before the pump goes off. 

Even with the 4.5 gallon tank the pump does not cycle for every toilet flush, but rather stays running until you are finished using water, then another 30 or 60 seconds, depending on the tank size 4.5 or 10.  You could flush 100 times in a row and the pump will only cycle once.  You can also flush, wash hands, start a shower, turn on a dishwasher or washing machine, or anyone else in the house can use water during the time the pump is already running, and the pump just continues to run until everyone is finished using water.  You don't just get a gallon with every pump cycle as you would without a CSV.

The advantage to the 10 gallon tank is an extra 30 seconds of run time to make sure you are finished using water.  This is advantageous if you have multiple people in one house or multiple houses on one pump system.  But most regular 3X2 houses with a family of 4-5 only need the 4.5 gallon tank.

tx2utila

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Re: Pump options for an off-grid, cistern only rain water collection
« Reply #7 on: August 17, 2020, 05:44:03 PM »
Thanks again for all the suggestions and explanations. I do have more questions regarding pumps and tanks.

First is size: I will probably go with the 10 gallon tank because the house will have 3 full baths, 3 people living in it full time with the occasional boost of up to 10. It's a house on an island off the coast of Honduras so we are expecting freeloaders, I mean visitors from time to time. We will also be all solar, most of the homes in the area are two story, our's is three (max shower height) is roughly 30'. They are all using 3/4 hp pumps. You have recommended 1hp. I think I need a 1hp, just want to make sure.

Second is make of pump: You have suggested either Gould or Grundfos. A lot of people on the island started out with Gould but have switched to Flotec. This environment is probably the harshest on earth.....salt.....moisture.....salt.....UV. Obviously the later won't be a problem because everything will be in the bodega. Thoughts?

Speaking of the environment, the sidekick tanks are steel. Everything on the island deteriorates at some point, some sooner than others. Would you still recommend the steel tank vs a fiberglass tank. Everyone down there uses 30 or 40 gallon fiberglass tanks. No one uses the CSV, they haven't even heard of it, they are all waiting for me to be the "experiment".

Thanks in advance.
Brad


tx2utila

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Re: Pump options for an off-grid, cistern only rain water collection
« Reply #8 on: August 18, 2020, 05:46:57 AM »
One additional question: I believe I read something about you can't have a foot valve and a check valve, only one or the other, correct? We are drawing water from a rainwater collection cistern  using a shallow well jet pump.

Thanks so much,
Brad

Cary Austin

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Re: Pump options for an off-grid, cistern only rain water collection
« Reply #9 on: August 18, 2020, 10:37:39 AM »
Thanks again for all the suggestions and explanations. I do have more questions regarding pumps and tanks.

First is size: I will probably go with the 10 gallon tank because the house will have 3 full baths, 3 people living in it full time with the occasional boost of up to 10. It's a house on an island off the coast of Honduras so we are expecting freeloaders, I mean visitors from time to time. We will also be all solar, most of the homes in the area are two story, our's is three (max shower height) is roughly 30'. They are all using 3/4 hp pumps. You have recommended 1hp. I think I need a 1hp, just want to make sure.

Second is make of pump: You have suggested either Gould or Grundfos. A lot of people on the island started out with Gould but have switched to Flotec. This environment is probably the harshest on earth.....salt.....moisture.....salt.....UV. Obviously the later won't be a problem because everything will be in the bodega. Thoughts?

Speaking of the environment, the sidekick tanks are steel. Everything on the island deteriorates at some point, some sooner than others. Would you still recommend the steel tank vs a fiberglass tank. Everyone down there uses 30 or 40 gallon fiberglass tanks. No one uses the CSV, they haven't even heard of it, they are all waiting for me to be the "experiment".

Thanks in advance.
Brad

The 10 gallon tank is a good idea.  But not so much because of ten people, more because you need more pressure.  With three stories and 30' rise I would run 50/70 on the pressure switch and set the CSV for 60 PSI constant.  For this you will need a pump that can build at least 80 PSI max.  Flotec is just a cheap box store version of a Pentair pump.  Goulds are still heavy duty and last much longer.  I also don't think Flotec has one that will do 80 PSI max?  The best Goulds for that much flow and pressure is the J15S. 

You could also use a submersible well pump in the cistern, as the multi-stage design builds a lot more pressure than a jet pump.  Plus the submersible is in the water and not exposed to the sea environment.  It is also much more quite and water cooled, so air temp is not important.

The 10 gallon tank with the PK1A can be of any brand you choose.  But the little steel tanks are best and can be easily sprayed with a can of Flex Seal, which works well to protect the tank from the elements and even burying when needed.

Cary Austin

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Re: Pump options for an off-grid, cistern only rain water collection
« Reply #10 on: August 18, 2020, 10:38:53 AM »
One additional question: I believe I read something about you can't have a foot valve and a check valve, only one or the other, correct? We are drawing water from a rainwater collection cistern  using a shallow well jet pump.

Thanks so much,
Brad

When drawing from a cistern a jet pump only needs a check valve on the suction side of the pump.  The submersible needs a good check valve on the discharge before connection the drop pipe.