Starting pump against reverse flow question

[Josh_Michigan]

Hello,

I built my new house and had a new well installed last year. The breaker to the well pump is tripping once or twice a week. It only happens when I'm running water from the hydrant at my barn. The line to the hydrant is Tee'd in to the main house line right at the well. The pressure tank is in the house. So when the spigot is used, water flows backward though the main line from the house, until the bladder tank kicks the pump on. My worry is that the pump is having to reverse the direction of the water flow in the main line when this happens, potentially causing a larger inrush current to start the pump. The water lines are 1-1/4" and the main line from the well to the house is 200', so that's a lot of water to change flow direction on. Could this be why it's tripping? Are there solutions for it? I can draw a diagram if that helps explain the layout better.

Thanks!!

 

[Valveman]

That might cause a little water hammer, but won't effect the pump. Pumps trip because they are shorted or are cycling on and off too much. Most likely when you run the hydrant you are not using enough water to keep the pump from cycling, which can trip breakers or overloads.

 

[Sponsor]

 

[SuperGreg]

Meh, it does have to reverse the flow but some flow goes out the spigot so I think it's a net equal. What size breaker and pump? Best way to check what's going on is an ammeter and measure inrush and running current in normal operation and when the breaker trips.

 

[Josh_Michigan]

Meh, it does have to reverse the flow but some flow goes out the spigot so I think it's a net equal. What size breaker and pump? Best way to check what's going on is an ammeter and measure inrush and running current in normal operation and when the breaker trips.

I believe it's a 1.5hp pump. It calls for a 30amp breaker. I know this will sound dumb, but I have a 25amp breaker on it right now. I will be putting a 30amp on it this weekend. My well driller said he runs his on a 20amp breaker and it never trips, which is why I'm wondering why mine doesn't work, but his does. The inrush current spikes so fast that it's hard to catch on my amp clamp, but I think it was 40-50amps for a split second, then runs steady at 12.7amps.

 

[Josh_Michigan]

My 10 gauge wire also runs about 240' from my panel to the pump, so maybe that has something to do with it also.

 

[Bannerman]

Assuming it's a submersible pump, since it will be down within the well, water should not be flowing in reverse through the pump, but the only reverse flow will then be from the pressure tank to the hydrant location.

List the pump model, the well specifications (well depth & diameter, static water depth, recovery rate, pump depth), pressure switch pressure setting range, the hydrant flow rate, and also the location of any check-valve(s) and other flow restrictions. List also the wire size between the pressure switch and pump along with the breaker amp rating.

Perhaps there is sufficient voltage drop over the 200' horizontal distance + ? vertical distance within the well, thereby resulting in increased starting current draw which exceeds the breaker rating?

In addition, the pump will consume higher current when starting when there is low backpressure. This could occur if the hydrant flow rate is high enough to cause the pressure within the supply line to fall substantially lower than the pressure switch cut-in pressure before the pressure switch can sense the pressure drop so as to activate the pump. Because the pressure switch and the pressure tank are located close to each other a long distance away from the hydrant, any flow restriction between the pressure tank and hydrant, could slow the speed in which the pressure switch senses the rate in which the pressure is being reduced while the hydrant is being fed initially from the pressure tank.

 

[Reach4]

Could this be why it's tripping?

1. At what stage in the pump cycle does the breaker open? 10 seconds in? 1.5 minutes in?

2. I presume a 2-pole breaker. How many amp breaker?

3. Please address SuperGreg's questions in #3.

 

[Valveman]

I believe it's a 1.5hp pump. It calls for a 30amp breaker. I know this will sound dumb, but I have a 25amp breaker on it right now. I will be putting a 30amp on it this weekend. My well driller said he runs his on a 20amp breaker and it never trips, which is why I'm wondering why mine doesn't work, but his does. The inrush current spikes so fast that it's hard to catch on my amp clamp, but I think it was 40-50amps for a split second, then runs steady at 12.7amps.

My book shows locked rotor or starting amps at 52. Needs a 30 amp breaker.

 

[mark1126]

It's unlikely that reversing the water flow in a 1¼" line is causing enough extra load to trip the breaker. A well pump should be able to handle normal flow changes without excessive startup current. More likely causes include a failing pump motor, bad capacitor, wiring issue, pressure switch problem, or an undersized/weak breaker. Since it only happens when using the barn hydrant, the pump may be running longer or cycling differently, exposing an existing electrical issue. Have the pump's current draw and electrical components checked first. A diagram of the system would help diagnose it further.