Well for Irrigation, Selecting contractor, pump, etc.


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Old 06-23-11, 06:24 AM
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Well for Irrigation, Selecting contractor, pump, etc.

Ok, I currently have an irrigation system for my 1 acre yard. I have rainbird spray heads and hunter rotary heads. I have 14 zones total. 11 zones are rotary (4 or 5 heads per zone) and I have 3 zones for spray heads (9-11 heads per zone). I am having a well drilled approximately 260' strictly for irrigation purposes. I have received quotes from $4,300 to $6,300. When asking a contractor why such a difference, I am told it is because of the pump and material, or slow work. I am a little concerned about the pump. Not knowing much about submersible well pumps, the brands from the different contractors are as follows: Myers 1.5hp, Jacuzzi 1hp, Goulds 1.5hp, and J-Class Franklin electric 1.5hp. Some are 220V and some are 230V. Some need a 30amp breaker and some need a 20amp breaker. Some produce 20gpm and others 35gpm. I was leaning towards one of the contractors who use the J-Class Franklin electric 1.5hp/ 230v/ 20amp pump which produces 20gpm. I just donít know if that is good or not. Is the more gpm necessarily better? My assumption was the more gallons per minute would be the less of a cost to run my pump since it would be on for less time. Can someone shed some light on this. Sorry to be all over the place here, but this is a big expense and I donít want to make a mistake. thanks
 
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Old 06-23-11, 09:50 AM
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You need to look at each of your irrigation zones and the heads installed and calculate the GPM and pressue needed. Then look at the performance charts for each pump you are considering making sure to factor in the depth from which you will be pumping the water. Also look at your plumbing to calculate for friction loss in the piping.

Picking a pump before the well is dug involves a fair bit of guessing. I would have the well dug first as a separate job (with no pump). Then once the well is in the ground you will know it's depth, how many gpm the well can provide and how far down the water is located. With that information you can better choose a pump.
 
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Old 06-23-11, 09:57 AM
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If you are using pop-up spray heads make sure to include a rather generous bit of extra flow to initially get the heads to pop-up and seal. When they heads are up and sealed their flow will be based on the spray head/nozzles but when they are down you have the normal flow through the head/nozzle plus a fair bit of leakage so it takes more flow volume initially to get them popped-up.
 
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Old 06-23-11, 10:14 AM
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You're going at this bassackwards.

Don't pick a pump until the well is done. Then, pick the pump based upon what the well will do. Then reconfigure your zones, if necessary, to match your pump output. As Pilot Dane said, leave plenty of overhead for dry times.

Reason is that 1/2" thinwall, $10 valves and $20 control boxes are ahelluvalot cheaper than new pumps and wells.

I dunno if I would buy a pump anymore if I couldn't get a pump curve for it. A decent retailer should be able to provide you with one. Realize that those curves are based on IDEAL circumstances. Knock off 10-15% for the world we live in.

Over time, GPM available from a well declines. So if you start out with a well that can do 20GPM max, and you put a 20 GPM pump on it, in a few years, you will start sucking air and/or your whole elaborate sprinkler system will stop working properly as in you won't be getting full coverage. I can't tell you how much it will decline, but when it has declined "enough" we say it has run dry.
 

Last edited by Vey; 06-23-11 at 10:33 AM.
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Old 06-23-11, 12:23 PM
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Pilot Dane said:
"You need to look at each of your irrigation zones and the heads installed and calculate the GPM and pressue needed."

You do this by finding out what GPM each head needs to work properly. Most manufacturer's have websites, so if you have the make a model, you can look up the specs.

Some are adjustable and sometimes installers will put in colored flow (I don't know the name of them so let's call them restrictors) restrictors. These things reduce the flow of the water and reduce the GPM and raises the pressure. They are found where the head screws into the pipe, so watch out -- the manufacturer's specs may have been fiddled with to balance the zone.

Then, you add up the GPM requirements on each zone. Here is an example: A particular sprinkler head needs 3GPM operating at 25PSI. There are 6 of these on a zone, so it would need 18 GPM at 25 PSI to have the zone working properly.

One thing to know about irrigation wells vs. drinking water wells is that the pumps are very different. On a drinking water well, high pressure is required and much lower GPM is okay. If you poke around on here, you will find people with 1,2 or 3 GPM wells running at 50 or 60 PSI.

Irrigation is the exact opposite. High GPM is a requirement and lower pressure is okay. Most sprinkler heads are designed for 20-35 PSI (check the specs of yours). If your sprinkler is not getting enough GPM, then what you will see is a stream coming out and not a "curtain."

That's why I always tell people that they should have two wells. Running your drinking water well dry while sprinkling your lawn can ruin your whole day and sometimes a week.

The rainbird website has a lot of good info on it about irrigation. You may have to read the "professional" side of the site, but take your time and digest it all. You are saving yourself money.
 
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Old 06-23-11, 03:52 PM
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I would say that the range of prices you have received is probably pretty good for a 260 ft well with a pump installed.

The more GPM a pump is rated for, the less it should cost. The reason being is that a 10-gpm pump has more stages than a 20 gpm pump when comparing equal horsepower pumps. The 10 GPM pump can do more pressure. Plus the GPM depends on the curve.

I have used quite a few of the Goulds 1.5 HP and have been satisfied. There is no difference in 220/230, some people just use different lingo. It's the same voltage. Just like some people refer to 110V or 115V.

I heard that Franklin now owns Jacuzzi, so I'm unsure if there is any difference between the J-Class and the Jacuzzi. I know the J -Class is very popular.

You really need to size your GPM of the pump based on how much water you are using. The pump curve will tell you what you need to know. 50 psi = approx. 115 ft of head, then add in the depth to the water in the well and look at the curve.

Good luck.

Originally Posted by cmisti66 View Post
Ok, I currently have an irrigation system for my 1 acre yard. I have rainbird spray heads and hunter rotary heads. I have 14 zones total. 11 zones are rotary (4 or 5 heads per zone) and I have 3 zones for spray heads (9-11 heads per zone). I am having a well drilled approximately 260' strictly for irrigation purposes. I have received quotes from $4,300 to $6,300. When asking a contractor why such a difference, I am told it is because of the pump and material, or slow work. I am a little concerned about the pump. Not knowing much about submersible well pumps, the brands from the different contractors are as follows: Myers 1.5hp, Jacuzzi 1hp, Goulds 1.5hp, and J-Class Franklin electric 1.5hp. Some are 220V and some are 230V. Some need a 30amp breaker and some need a 20amp breaker. Some produce 20gpm and others 35gpm. I was leaning towards one of the contractors who use the J-Class Franklin electric 1.5hp/ 230v/ 20amp pump which produces 20gpm. I just donít know if that is good or not. Is the more gpm necessarily better? My assumption was the more gallons per minute would be the less of a cost to run my pump since it would be on for less time. Can someone shed some light on this. Sorry to be all over the place here, but this is a big expense and I donít want to make a mistake. thanks
 
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Old 06-24-11, 05:41 AM
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This is Great

Thanks for all the advise, this is great. The sprinkler head nozzles are Hunter PGP and are currently 3gpm, and each zone has either 4 or 5 heads. So I guess I need to figure out the PSI and a bunch of other things before selecting the pump. The well is definitely being drilled at 260'. Thanks again and keep the advise coming.
 
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Old 06-24-11, 06:06 AM
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You usually don't specify the well's depth. Sometimes they hit a good supply of water closer to the surface and sometimes they have to go deeper. It would help the driller if they knew how much water you wanted to get from the well. Example: If they think the well is only producing 5 gpm from the well but you say you need to pump at 15 gpm for your irrigation they can go deeper to create a reserve so you can pump at the higher rate for 10-15 minutes, then have a pause between zones to let the well recover.

Hopefully you will get lucky and get a lot of water shallow and end up saving money with a shallower well.
 
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Old 06-24-11, 07:22 AM
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Neighbor across street just had well drilled and it was 260', can't imagine it being much different than that. thanks again
 
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Old 06-24-11, 07:53 AM
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My well is 180' and produces well. My neighbor on the adjoining property had to drill three wells before finally finding water two years ago. They went down to 500' on the first two holes before giving up and these two were located somewhat close to my well. They found water with the third well and is less than 300' and was located the furthest away from my much shallower well. Sometimes there is just no telling what's underground.
 
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Old 06-24-11, 08:09 AM
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Depth can vary, even for neighbors. The underground geology is not flat, it varies from place to place.

In my part of the country, quantity is not a problem. We can get all the way up to 100 GPM from a 4" well. In other areas of the country, 2-3 GPM is considered a good well.

Good luck and post up what you find.


Originally Posted by cmisti66 View Post
Neighbor across street just had well drilled and it was 260', can't imagine it being much different than that. thanks again
 
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Old 06-24-11, 02:45 PM
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i wouldn't have a problem with contractors that go ahead and give u prices on wells with pumps beforehand. to me it shows they are familiar with the area and confident in the results. if u can get a set price on a well (not price per foot), chances are good that they are definitely familiar with the area. some parts of country are hit and miss, some are predictable. experience helps alot either way

groundwater is different everywhere. not all wells lose production over time. without knowing the area's ground and the type of well being installed, i cant tell what to expect from it. a screened well will likely decrease over time, while there are some open bore rock wells over 80 years old that produce like the day they were installed. some wells run dry, some don't. some water levels fluctuate hundreds of feet, some very little.

as far as the price differences for the job, who knows. some guys are hungry, some are fat. some guys have millions tied up, some get by with junk. some use different methods. some go above and beyond for a customer and charge according. some cut corners and work cheaper. some cut corners and charge more. some use cheap parts, ..... u get the idea.

whatever decision u make, good luck and look forward to hearing results.
 
 

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