Control Box problem

[ian morrison]

Problem solved! Thank you all for your help and particularly, Valveman. The control box needed a jumper between SW and L2. Pump is working exactly as it should.

This might be of interest. While troubleshooting the pump, I checked the resistance for B-Y and R-Y. The value for B-Y was correct but R-Y was too low which would indicate a short. I was suspicious when I measured R-B and discovered it was the sum of the other too which it should be. Then I noticed that the R-Y number listed in the manual was not in line with the others-- from ½ HP to 5 HP that number decreases. But the listed Y-R value for 2 hp was higher than the 11/2 HP. I called Xylem and eventually got through to an engineer who confirmed that the manual was wrong and my readings correct. It was a relief not to have to replace the pump. Those of you who do this professionally probably see these errors from time to time.

Again, a big thankyou to all.
Ian

 

[Valveman]

Problem solved! Thank you all for your help and particularly, Valveman. The control box needed a jumper between SW and L2. Pump is working exactly as it should.

This might be of interest. While troubleshooting the pump, I checked the resistance for B-Y and R-Y. The value for B-Y was correct but R-Y was too low which would indicate a short. I was suspicious when I measured R-B and discovered it was the sum of the other too which it should be. Then I noticed that the R-Y number listed in the manual was not in line with the others-- from ½ HP to 5 HP that number decreases. But the listed Y-R value for 2 hp was higher than the 11/2 HP. I called Xylem and eventually got through to an engineer who confirmed that the manual was wrong and my readings correct. It was a relief not to have to replace the pump. Those of you who do this professionally probably see these errors from time to time.

Again, a big thankyou to all.
Ian

Technically you are supposed to run a wire from SW through one side of the pressure switch and back to L2. But I could tell you had already run power from the breakers through the pressure switch to L1 and L2 so I mentioned just adding a jumper between SW and L2, which will work. However, you have 2HP load running through the points on the pressure switch. Using the magnetic contactor in the MC control box and wiring the pressure switch through SW and L2 takes all the current off the pressure switch. The pressure switch can handle the 2HP load as long as you don't let the pump cycle on and off too much. Having a Cycle Stop Valve will make the pressure switch and everything else in a pump system last several times longer than normal.

 

[ian morrison]

Thank you for making that clear. There is no mention of this in the manual and I don't believe the schematics show it either. I really appreciate you pointing to a solution as I was out of ideas.

This is a vineyard pump and I'll test this week to see how many blocks I can water at one time for the fewest pump cycles. I should be able to keep cycles to a minimum and if so will leave things as they are. Otherwise, I will install a Cycle Stop Valve.

I read your post on the unnecessary use of multiple check valves and when I pulled the old pump I was surprised to discover three check valves--one 20 feet above the pump, one at the wellhead, and one between the wellhead and the sand filter. I have no record of when or who did the installation but I expect it was at least 20 years ago. I have just the pump backflow valve now so I expect some improvement in performance.
Again, thanks for your help.

 

[Valveman]

Thank you for making that clear. There is no mention of this in the manual and I don't believe the schematics show it either. I really appreciate you pointing to a solution as I was out of ideas.

This is a vineyard pump and I'll test this week to see how many blocks I can water at one time for the fewest pump cycles. I should be able to keep cycles to a minimum and if so will leave things as they are. Otherwise, I will install a Cycle Stop Valve.

I read your post on the unnecessary use of multiple check valves and when I pulled the old pump I was surprised to discover three check valves--one 20 feet above the pump, one at the wellhead, and one between the wellhead and the sand filter. I have no record of when or who did the installation but I expect it was at least 20 years ago. I have just the pump backflow valve now so I expect some improvement in performance.
Again, thanks for your help.

If you can make every irrigation zone match the exact output of the pump, there will be no cycling. But if any of your zones are a little small and causes the pump to cycle on/off, a CSV will save the pump while delivering strong constant pressure.