Irrigation system on a well pump

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  #1  
Old 09-08-13, 02:46 PM
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Irrigation system on a well pump

I am on a well. I have a 12 zone sprinkler system around my house. When these are installed, are they set up so the flow rate is calculated to be exactly what the well puts out, so the well isn't cycling on and off?

I've done some research, and I've read a couple things where people have said that your well pump should run continuously while your sprinklers are on. This make sense to me, because the well starting/stopping a bunch has got to be bad for it.

Some zones, it runs perfectly, and the well pump and zone work in unison so that the pump isn't cycling on and off.

However, I have a few zones where the pump will run for a minute, then shut off, then the system will lose pressure and cycle the pump back on. I can hear my pump clicking on and off about every 2 minutes. I know this can't be good for it (and it causes some water hammer as well). My system is set at 30psi low end and 50psi on the high end.

My basic question is - am I correct in assuming it should run continuously? There must be something up with the zones in question that are making it cycle. Perhaps they aren't putting out enough water?

Thanks for any tips.
 
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Old 09-09-13, 05:20 AM
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It sounds like you are using your house's well pump and not a dedicated irrigation pump. Your well system should have a pressure tank that minimizes the pump's cycling on & off. If you size the irrigation system so the pump does not cycle you are trying to strike a very fine balance between the pumps output and your sprinklers consumption. Unfortunately the output of the pump changes as the water level in the well changes so balancing it perfectly is almost impossible.

Your pump is cycling on and off frequently because you have a smallish pressure tank and your irrigation system is consuming a lot of water. You can split your system into multiple zones that consume less water so the pump does not cycle as often. You can also install a larger pressure tank.

The problem with trying to match your irrigation systems flow exactly to the pumps output when using your home system is that you can't use any water in the house when the irrigation is running. If you flush a toilet or run a load of laundry it draws extra water that the pump can not provide so the system pressure drops and you get a bad shower and your sprinklers don't shoot the proper distance.
 
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Old 09-09-13, 06:13 PM
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Thanks for the reply.

We don't have a dedicated irrigation pump. We do have a pressure tank, I'm not sure of the size but it's a standard size I believe for our size house (2600sq ft.)

We've got our sprinkler system in 12 zones so they split it up pretty good. Like I said, for most zones the system works pretty good and the well pump stays on.

I know if we use water while the sprinklers are on in the house (showering, etc.) it's going to throw it off but that isn't a big concern for me. Yes it will cause a little well pump cycling but not nearly as bad as it has been doing on some zones right now.

Do you think changing my pressure system from a 30psi-50psi to a 40psi-60psi would help?
 
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Old 09-09-13, 06:41 PM
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Normally a second well is used for irrigation. Make sure you don't run your primary well dry by over drawing from it.

In my opinion.....increasing the operating pressure of the system won't help. In fact as the system pressure goes up the refresh rate is longer as the pump has to work harder.

Your pressure tank is sized for the water system in your house...... not for the sprinkler system. The only way I can see to smooth out the cycling times is to increase the tank size like Dane mentioned above.
 
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Old 09-10-13, 07:58 AM
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Generally you do not want higher pressure for irrigation. Most residential systems are actually designed for about 30 psi and many companies sell regulators to drop the pressure to the irrigation system.

Builders and plumbers often go with the smallest size pressure tank they can to save money and space, and honestly most people never notice. The well cycles a bit more often and the pump only last 12 years instead of 15. In general I think the largest pressure tank you can get would be the best or even gang another one in with your current to increase the tidal capacity.

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I have a very small irrigated are at my house and am also on a well. The flow to my irrigation system is limited by the 3/4" line & fittings leading to it at about 6 gpm reliably even when the system pressure is low (right before the pump cycles on). My pressure tank is about 80 gallon size with about 35 gallons tidal capacity which allows about 5 minutes irrigation flow before the pump turns on. I have my zones each programmed to water for 4 to 6 minutes with 15 minutes between each activation. This way my pump only comes on about once for each irrigation cycle and gives the pump a good 10-15 minutes cool down between pumpings. This also allows sufficient reserve capacity in my system that we can do anything in the house (water use wise) without noticing that the irrigation is working.
 
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Old 09-12-13, 08:49 AM
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Your pressure tank is sized for the water system in your house...... not for the sprinkler system. The only way I can see to smooth out the cycling times is to increase the tank size like Dane mentioned above.
When you say increase the tank size, you are talking about the bladder tank?
 
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Old 09-12-13, 01:41 PM
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Yes, larger pressure/bladder tank.
 
  #8  
Old 10-02-13, 06:27 AM
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We have a "cycle stop valve" that works for us. Well pump stays on constantly when irrigating. No off and on cycles which cost $$ and might be harmful to your pump.
 
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Old 10-16-13, 04:36 AM
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do you live in lake Isabella? sounds familiar to the situation someone I know has. there is not a lot you can do when you have little demand and lots of supply other than a huge tank(not practical and the heads will operate for an extended time at too low of pressure) or get what the latter recommended non-cycling valve or a grundfos anti cycle... Otherwise you need more heads on that zone or bigger nozzles if you even can.
 
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