Ask Me Help Desk - Well pump cycle

Hi, I recently installed a well system on my small ranch. The system consist of a 520' bore hole, 5hp pump set at 480, 119 gal pressure tank with pressure switch set at 40/60 psi, tank pressure is set at 38 psi.

The system works well, lots of water with great pressure. My problem is that the pump fills my tank in 1.05 minutes! The pump which is rated at 19 gpm is actually pumping at 25 gpm!

I have been told that this short run time is bad for the pump; causing it to wear out prematurely ,

What is an acceptable runtime for a submerged well pump and what do I need to do to achieve an acceptable runtime?

Any assistance will be appreciated.

A 5 horse pump is BIG. I'm not surprised you can fill your tank quickly. If you want to increase your cycle time, then you could add a second tank (serious money for 119 gallon tank), but I wouldn't worry about it. Think of it this way. You have to use 30 gallons or so of water in the house before the pump kicks back in.

Actually, if your tank is this one: Amtrol Well-X-Trol 119 Gallon Water System Pressure Tank - WX-350 - WX-350, then the drawdown on that tank is 35 gallons. That means you are closer to 30 gpm than 25.

Is your tank a bladder tank?

Quote:

Originally Posted by jlisenbe

A 5 horse pump is BIG. I'm not surprised you can fill your tank quickly. If you want to increase your cycle time, then you could add a second tank (serious money for 119 gallon tank), but I wouldn't worry about it. Think of it this way. You have to use 30 gallons or so of water in the house before the pump kicks back in.

Actually, if your tank is this one: Amtrol Well-X-Trol 119 Gallon Water System Pressure Tank - WX-350 - WX-350, then the drawdown on that tank is 35 gallons. That means you are closer to 30 gpm than 25.

Is your tank a bladder tank?

Thanks for the come back!

Yes, the tank is a bladder tank Flexcon 120 Gallon Fiberglass Pressure Tank (http://www.aquascience.net/flexlite-pressure-tanks/index.cfm?id=846) with the same drawdown.

My only concern is the short runtime of the pump. I read somewhere or was told that a deepwell pump needs to run at least 2.5 minutes for longevity sake?

When my irrigation system is running it is on and off about every ten minutes (for one minute at a time) for the 90 minute irrigation time.

I don't think it's the length of time the pump is on as much as how frequently it has to start/stop. The worst time for a pump is startup. Your cycles are every ten minutes, so you're using 3 gallons or so of water a minute. If the pump pumped 5 gpm, it would still be a ten minute cycle, one start/stop sequence each time. That's the key thing. You have a pump that seems a good bit too large for what you are doing, but I've never heard of that being a problem. Probably means it will last that much longer.