Is this water pump is short cycling?

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Mike77

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What is the definition of when a water pump is short cycling?

I have a 200 ft. deep well with a 1 hp Grundfos submerged pump and an 80 gallon pressure tank without a diaphragm. With the pump shut off at 57 psi I open one cold water faucet in my house and leave it open. The the water runs for 2 minutes and 53 seconds with the pump off until the pressure goes down to 25 psi then the pump turns on for 17 seconds until the pressure gets back up to 57 psi with the faucet still open. Then the cycle repeats.

Is this a good run time or a short cycle?
 

Valveman

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NO. Not good. An 80 gallon tank should hold about 20 gallons of water. A cold water faucet might use 1-2 GPM. It should take about 10 minutes to drain the tank and start the pump. Then with a 10-20 GPM pump, the tank should refill in 1-2 minutes, not 17 seconds. So yes your pump is short cycling. One minute on and one minute off is minimum run and off times.

So called "normal cycling" every minute or two will eventually break the bladder in the tank the same way bending a wire back and forth will cause it to break. Once the bladder breaks the water gets in the air chamber and causes shorter and shorter cycles until the pump itself is toast.

Here is how a pressure tank works and how to use a Cycle Stop Valve to prevent cycling. The CSV makes the pump last longer, can use a much smaller tank, and makes shower pressure so strong you will no longer even need soap. :)

 

Mike77

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Thank you for the information Cary, the well driller said that my well pump had a good run time.

The well driller drilled my well about 2 and 1/2 years ago and put in the system for $7,000 but it took me 2 years to build my house and move in so I have only been using the well for about 6 months. The well driller has since retired now and I don't think it ever had a warranty or it expired. The driller's son took the business over and answers the phone now. I haven't been able to speak to his father. His son has never seen my well and doesn't want to look at it. He is the one who said it had a good run time . It might have short cycled since the day it was installed. Tapping the tank it sounds 90% full of water. I will post the results of the 5 gallon bucket test later.
 
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Reach4

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Thank you for the information Cary, the well driller said that my well pump had a good run time.
You have a "conventional"/"galvanized" pressure tank. Its capacity is a lot less than the air pre-charged tank of same size. So your 80 gallon tank may be only good for 8 or 10 gallons. Now would your possibly-oversized pump be able to supply 9 gallons in 17 seconds? It seems unlikely.

Bypass the softener. Try your pump-off test again at the tub. Again have the pump run to its shut-off pressure. Then see how many 5-gallon buckets you fill before the pressure switch clicks (you would need a helper)? Faucet flow can vary a lot. Alternatively, connect a hose to the drain valve and fill the bucket. Now you don't need a helper.

I only suggest bypassing the softener in case you burp a lot of air by mistake.

I am not a pro.
 
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Reach4

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Based on prior posts, I expect you will get about 3 gallons before the switch clicks, because there is not enough air in your tank.

If you get a compressor, look at the SCFM rating. Do not consider a "150 PSI" pump for this. Most of those have a hard time pumping up car tires.
 

Mike77

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Thanks Reach4, but I was told that you only add air to a bladder tank never to the snifter valve on a tank without a bladder because the pump has to add air through the snifter valve every pump cycle since the previous air charge is used up.
 

Reach4

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Normally that is true. But for the test+workaround reasons, adding air would be good.

There is a flaw to adding air at your snifter, however. The air could escape out of the downstream hole (presuming it is not clogged) faster than a small compressor could add air, leaving none to add to the air in the tank.

You could tee off the port going to the pressure switch to add another Schrader valve (downstream of the check valve) that would let you add air. You don't want to add so much air at the same time that the pressure in the tank becomes excessive (over 80 would be excessive).
 

Mike77

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Reach4, I ran the test you suggested twice. I have neither a water softener nor a water filter. With the pump shut off and pressured up to 55 psi, with a hose coming out of my water valve by the pump I can only get out one gallon and one half of water before the pressure drops to 25 psi and the contacts close turning on the pump again. So only 1.5 gallons of air is in my pressure tank. It is extremely water logged. I think the well driller made some installation mistake.
 

Reach4

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Or the hole in the pipe is blocked, too small, or too high... as discussed above. I guess any of those could be considered a well-driller mistake.
 
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Mike77

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I think I found the reason for the water logging. I drained the pressure tank and refilled it. Then I sprayed soapy water all over it. There are bubbles coming out of the threaded plug on the very top of the tank. So I am going to remove it and put teflon paste on the threads and put it back in.

Then to see if the tank is taking in air like it should and to get a reference point; with the pressure up to 55 psi and the contact points open I ran a hose in to a bucket. I opened the valve and watched as the pressure was down to 25 psi and when the contact points closed I had about 9 gallons of water that had ran instead of the 1.5 gallons I was getting when it was water logged.
 
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