getting the most out of my well


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Old 09-22-08, 01:24 PM
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getting the most out of my well

I was wondering if there are any adjustments that can be made to my pump setup to get more water. I have an 2" deep well, 85 feet deep. The suction line is 1.25" and the return line is 1". My drop pipe 1.25" and is 40 feet. About a week ago my water table was about 18 feet. There is about 65 feet of horizontal pipe from my well packer to my pump. My pump is a Myers 1hp and I have a 45gallon pressure tank. My pressure switch is set at 30/50. According to the Myers pump website, I should be getting more water. After doing a lot of measuring and testing I have come up with the following number my well is producing:

11.5 gal/min @ 30psi
8.1 gal/min @ 40psi
5 gal/min @ 50psi.
My pressure/gpm is being measured at a 1" discharge pipe.

I have also noticed that when I have my valve all the way open for a while my pressure drops to 0 and my gpms drop off significantly. As I close the valve the pressure builds and the gpm increases. Is this wierd? Any ideas? Also is there some kind of "flow controller" bolt on the pump?
 
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Old 09-22-08, 03:01 PM
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There are two types of pump. Those that pump pressure, and those that pump volume. From the numbers you posted. You may have a volume pump. Or some impellers may be going bad. Most deep well pumps need some back pressure, Its called (jet pressure). When you open the valve, you take away the jet pressure, and the pump cant do what is was designed to do.
Not all the numbers you find on line, are the same as the numbers that are found in the field.

Travis
 
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Old 09-22-08, 03:35 PM
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What I am trying to do with this well is irrigate my grass....about a quarter of an acre area to be watered. I have been reading the rainbird free diy irrigation plans and they say I am going to need a minimum of 40 psi to operate a sprinkler system. But when I look at their products most of the sprinklers I will be using only require between 15-25 psi to operate. My well will ONLY be used to water grass. My house is on city water. Is rainbird coming up with the 40psi because they are trying to account in for other water usage on the system, or is the 40psi mandatory? Will I have to have a lot of zones to do this system?
 
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Old 09-22-08, 03:52 PM
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The amount of pressure is a side note. That is what it take to make the sprinkler go around. The amount of water (flow) or gpm. Is what you need to look at. Your pump may be able to pump enough psi, but cant pump the amount (flow) of water you that you need to water the grass.

If you are using 5 sprinklers at 15 gpm. You may need to use 4 or even 3 sprinklers, witch will reduce the gpm to, lets say 10 gpm or even 8 gpm. Each of your sprinklers will say how much water it will let through. It will be listed in GPM.

You will probably need 5 to 7 or even up to 10 zones to water what you need to. It just depends on how much water your pump will let you have.

Travis
 
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Old 09-23-08, 10:21 AM
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Here is another question for you. As you can see in the picture below, there are some offset fitting that connect my pvc pipe to my packer. The reason they are there is because the old galvainzed pipes that were replaced were not as deeply buried as my new pvc. I just connected my new pvc pipe to the offsets. Before I bury the pipe, would it be beneficial to remove the offsets and have the pvc running directly into the packer? What kind of effect could it have on my pressure/volume? Thanks.
 
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Old 09-23-08, 02:44 PM
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It will have a small effect on the flow, but not that much. Not enough to warrant changing the pipes. The pipes you have will be fine. You will just have to zone your yard accordingly.


Travis
 
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Old 09-24-08, 04:16 PM
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Originally Posted by waterwelldude View Post
The amount of pressure is a side note. That is what it take to make the sprinkler go around. The amount of water (flow) or gpm. Is what you need to look at.
Rainbird says that 40psi is minimum to run their system. Ok here is a scenario and please correct me if I'm wrong. I would like to design my system with a pressure of 30psi. I factor in a 5psi loss for my antisiphon backflow preventer valve, 0psi loss for elevation change since my property is level, and a 3 psi loss for my lateral pipes. That would leave me with 22psi to operate the sprinkler heads. Wouldn't that mean that I can operate as many spray heads (that require either 15 or 20psi to operate) on each zone as long as I don't exceed my GPM?
 
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Old 09-24-08, 05:54 PM
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If you are going to tie your sprinklers to the back side of your tank. Open the valve that is going to the sprinklers. The pressure will start to drop. When the pressure get to the pressure you need to operate the sprinklers. Start to close the valve, until the pump hold the 40 psi on the gage. The amount of water coming out of the valve, is the gpm you have to work with to run your sprinklers.

You may only be able to have 2 to 3 sprinklers per zone. Then it also depends on what size nozzles that you might need to cover the area you are trying to water.

It all comes down to how many gpm's you have to work with, while holding 40 psi on the tank.


Travis
 
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Old 09-24-08, 05:54 PM
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30 PSI is a good number.

Most sprinkler heads need 3 GPM to work properly at 30 PSI.
So, if your well and pump can produce 9GPM, don't use more than 3 sprinkler heads.

If you get the GPM right, the pressure will follow.
 
 

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