What's Worse - Pump Cycling Or Running Continuously? - Plumbing - DIY Home Improvement | DIYChatroom

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Old 06-26-2009, 09:44 AM   #1
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what's worse - pump cycling or running continuously?

I've been reading that a jet pump continuously cycling (short cycles) will burn out a pump relatively quickly. I have a small bladder tank (5 gal) and small pump (1/2 hp shallow well jet) right now just to get me up and running - and what I seem to notice is that when I run a fixture wide open (e.g. garden hose) the pump just runs continuously. I assume this is normal. If I had a bigger pump I also assume it could move more water and fill the tank at the same time as I'm running the hose - e.g. the system would more likely cycle on and off?

so what's easier on the pump - longer continuous run vs the add'l stress on the pump from cycling more often? And how long can a pump run continuous before overheating (ballpark estimate...?)

sorry if this is a bit brain dead but just trying to understand the bigger picture.



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Old 06-26-2009, 10:48 AM   #2
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The fact that your pump runs continuously when a fixture is open suggests that the air bladder tank has lost much of its air. If so, that is a simple fix, either replace the tank or get it filled if it has a fill valve.

To the bigger question, all pumps have a finite lifespan, generally determined either by the number of on/off cycles, or the total length of time running. In my experience, only commercial pumps are ever designed to run continuously, normally a jet pump is not. Well pumps are designed to cycle frequently, so their life is likely limited by the total amount of run time. Similarly, sewer ejector pumps are designed for frequent cycling.

Only specialized pumps are designed for continuous duty, for example process chemical pumps, water pumps used in municipal systems, or pump storage turbines/pumps. Not likely you have one of those. So, short answer, don't worry if the pump cycles, but do check to see if the air bladder is short of air.


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Old 06-26-2009, 01:36 PM   #3
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Daniel - will do - thank you for the reply
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Old 06-27-2009, 01:01 PM   #4
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All residential and "commercial" well water pumps are rated continuous duty.

The only difference between the two is the size, gpm and hp, and the increased price.

Cycling on/off kills pump motors; it is the primary cause of motor/pump failures.

Your pressure tank has nothing to do with your pump running continuously when you run a garden hose. That's impossible, if the tank was full of water because of being 'waterlogged' or having a broken bladder, you'd get more water to the hose and the pump would shut off with just a bit less water use (gpm). To have a pump shut off when using a hose, you need a large gpm and possibly hp pump that will deliver higher pressure and more flow (gpm).
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Old 06-18-2012, 05:58 PM   #5
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minimum run time for well pump


Have you ever heard that the well pump should run for a minimum of one minute before tripping off?

Thanks. Jim
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Old 06-18-2012, 09:06 PM   #6
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If you install a larger pressure tank (or another pressure tank) the length of time between when you open a faucet and when the pump starts will be greater. Thereafter if the gallons per minute the pump can deliver is not greater than the GPM out of the faucet the pump will not stop.

The pump stops only after the system pressure is raised again to the pump turn off pressure which happens only after a quantity of water has has been put back into the pressure tank(s).

No harm having more than one pressure tank.


The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.
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