Is it normal for a 1/2 hp submersible pump to be on for 30 seconds from cut-in to cut-off?

[Milly]

Our home setup is 10 years old. The pressure tank was replaced two years ago with another 20 gallon (75 litres) Pentair Wellmate. The pressure tank was checked a week ago and is at 28psi with the pressure switch set at 30-50. Everything appears to be fine. I don't really have anyone around me who pays attention to these things so I'm asking if this sounds normal. Pump draw is 5.04 amps. Well is supposedly 225 feet deep.

 

[Valveman]

Yes, 5 amps is good for a 1/2HP. Replacing the tank is a sign the pump is cycling on and off too much. A 20 gallon tank only holds 5 gallons of water, which causes lots of cycling. 30/50 is very low pressure these days. 40/60 is more common. Probably a 5 GPM pump so, it will build lots of pressure. It is your water system. You can have as much pressure as you want. It can easily be turned up to even 50/70 if you wanted, and adding a CSV to get a strong constant 60 PSI will eliminate the need for soap. Lol.

 

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[Milly]

I am considering the CSV1A Cary. But back to the pump run time (cut-in to cut-out), it seemed like people were reporting a minute or two or three which varied greatly to my 30 seconds. So the 30 seconds is within spec?

 

[Valveman]

I am considering the CSV1A Cary. But back to the pump run time (cut-in to cut-out), it seemed like people were reporting a minute or two or three which varied greatly to my 30 seconds. So the 30 seconds is within spec?

With a 5 gallon size tank that holds 1.2 gallons of water 30 seconds is about right. With the pressure switch at 40/60 and the CSV at 50, the last half of the tank will fill at 1 GPM rate and take about 30 seconds.

The old standard is 1 minute is minimum run time, 2 minutes is better, and running continuously 24/7/365 is best for the pump/motor. That really doesn't apply when using a CSV. The CSV causes the amps to drop, de-rating the motor load. making it run cooler, and therefore it doesn't need as much time to cool down before shut off.

But still, the 30 seconds of run time is AFTER the pump has run long enough to supply the water that was used. The pump will run for 30 seconds to fill a toilet, then another 30 seconds filling the last half of the tank to 60 PSI. The CSV makes the pump run for the entire 5-20 minutes the shower is on, and then another 30 seconds to fill the little tank. The only way to make it run only 30 seconds is to have a small leak that slowly drains the tank. Even then the 30 seconds of run time is while the motor load is de-rated and it doesn't need 60 seconds to cool down.

 

[Milly]

Cary, the pressure tank is 20 gallons as mentioned in the first post. From cut-in to cut-off, maybe finishing a toilet fill, it takes 30 seconds. Is that normal?

 

[Reach4]

Cary, the pressure tank is 20 gallons as mentioned in the first post. From cut-in to cut-off, maybe finishing a toilet fill, it takes 30 seconds. Is that normal?

So that would suggest that the flow from the pump is about 10 GPM (20 gallons /4/(0.5 minutes) or a tad more to account for 1 or 2gpm for the toilet fill. If not using a CSV, you would be better with a 44 gallon tank.

 

[Bannerman]

From cut-in to cut-off, maybe finishing a toilet fill, it takes 30 seconds. Is that normal?

Thirty seconds to refill the pressure tank is not usual and not recommended.

As mentioned above, to reduce the frequency of pump cycling, the minimum recommended running time to refill a pressure tank is 60-seconds, but 120-seconds run time is preferable to further reduce cycling frequency. To obtain 120-seconds minimum run time with your existing pump, would require an 80 gallon tank which will provide approx 20 gallons drawdown capacity.

Instead of incurring the substantial additional expense for a much larger pressure tank which will also consume additional space, you could instead install a CSV. Because a CSV will prevent the pump from cycling whenever the pump is operating and more than 1gpm is being consumed, a large pressure tank is no longer needed. Although a CSV and a 5 gallon tank is quite sufficient for most single family residence applications, you could continue to utilize your existing 20-gallon tank with a CSV if desired.

A CSV will fill 1/2 of the pressure tank's drawdown capacity while at the same time supplying constant pressure to house fixtures. Your existing 20-gallon PT will then be 1/2 filled with ~2.5 gallons water. Once no further water is being consumed, the CSV will permit the pump to supply only 1 GPM to fill the tank's remaining ~2.5 gallon drawdown capacity. With ~5 gallons now within the tank, the pressure will have risen to the pressure switch cut-out pressure, causing the pressure switch to shut off the pump.

 

[Valveman]

Like Bannerman said, filling the 5 gallons in a 20 gallon size tank when using a CSV should take about 2 minutes. With the CSV set at 50 and using a 40/60 switch, the CSV should take 2 minutes to put the last 2.5 gallons in that size tank.

 

[Milly]

Are there any Canadian distributors for the CSV? If I have to purchase from the U.S., can I specify USPS as the carrier? In the meantime, I'll try to round up one or two others.

 

[Fitter30]

When checking tank pressure turn power off to pump, open both hot and cold valves to drain pressure off then check tank pressure.