Testing the current draw of the motor would be a good place to start.
At first it seemed easy enough... I had some old and poor corroded wiring going to an expensive, yet old Sta-Rite HNE-L shallow well jet pump. The original owners of this church had used a simple 110 volt plug into a receptacle for power. This caused the brass plug ends to burn up, etc. So, I resolved this with a very big switching system and new wiring, but the new pressure switch burned up also. Okay so I need to repair the pump. Capacitor is good... but the corrosion is so bad that I can not get this apart without some risk of damaging components or worse the motor itself. I will have to use my torches to get the long and narrow bolts out of the housing to even begin to look at the issues in this.
I had thought it is a bit noisy and may not worth repairing. At least not until I found the same replacement pump is going to be $800. It has specs; 28.5 GPM 1HP 25 ft of draw 1.25" in and 1 inch out. I fantasized about using a irrigation pump, had a laugh and looked around. I see of course some "shallow well" pumps such as the "Red Lion" and it seems not so costly, but it seems to be a centrifugal pump.
Unfortunately for our church gardening club I have little experience in wells or the issues of why a pressure switch will burn out. I am very good at electronics and electricity, rebuilding generators, alternators, motors and such. Also a lot of experience in machines and hydraulics but not wells... I am very, very tired after a hard weekend so after looking for answers on the net my question now is; anyone have any advice on my path here? Are we stuck using city water to irrigate the most needed trees, etc and forgo the garden until we can buy the same unit?
I did note that once I took the pump out the water level in the intake pipe was at the very top and this is about 14 inches from the ground here in St Pete, FL. This makes me wonder if an irrigation pump may be okay for this application? Granted there may be a check valve involved in this too. There is a rainbird controller and we would be watering less than half acre of land, and can use several zones to do this so I am wondering if I can use a smaller pump until we can put together some money for this big one? Any links to a source to help me figure out how I can break up the system into smaller runs would also be great. Our church and community center doesn't get money for what we do and we do not want to start charging for what we do so I like to be creative... if possible.
I thank you for taking the time and interest to read through all this. I apologize for the length as I am not entirely certain of what I can do with what we have here.
Testing the current draw of the motor would be a good place to start.
Don't take the pump/motor apart until you are sure it is needed. Pressure switches burn out because the pump is cycling on and off too much. If you only use the Ranibird controller to irrigate with, you don't need a pressure switch or pressure tank. Just hook up the pump start relay from the Rainbird controller directly to the motor (no pressure switch). Using the Rainbird controller to turn on the sprinklers while letting the pressure switch turn on the pump, is why the pump is cycling on and off so much and causing problems.
If you use hoses from hydrants to irrigate with, you need some way to eliminate the pump cycling.
If the pump is bad, there are less expensive versions that will work. Even an irrigation centrifugal will work if you don't need much pressure, and are not using the pressure switch and pressure tank.
The amp draw when I tested it before replacing the wiring and the 110 volt leads was only 2 amps using a typical inexpensive induction amp meter. This at the time seemed low, but I do not have any specs that help me than the tag which says max rated at 9.6 amps. 2 amps should not cause much heat damage for a device rated at 9.6 amps?
As for cycling... maybe, I am going to put the motor/pump back on and retest the draw and count the cycles when irrigating... I will report back after this. I am fine with bypassing the pressure switch. But, the thing is the pump is powered through this pressure switch... how would I use the rainbird system to take over this job?
I have a very, very big industrial switch that feeds the 110 into 2 separate lines. One to the rainbird system controller and one to the pressure switch. Is there a schematic that I can look at to see what you are suggesting as far as removing the pressure switch from the system? I am fine with getting rid of the tank and pressure switch as this system is only used to water the grounds.
How about if I only turn the pump on directly once I have the rainbird system running? Does this pump have some kind of built in pressure circuit at the back of the motor? Looks like it does as there are the springs with a weight that would be actuated internally. Or it looks that way from where I am looking.
Thanks for your time and interest...
2 amps is not going to cause any problems with the pressure switch. Either you had a poor connection which became hot, or the contacts were bouncing.
If it is not, the switch must be mounted at the pressure tank. I would make sure that line to the switch is not clogged/restricted and make sure that the voltage is not dropping under a load.
Like valveman said, excessive cycling will shorten the life of switches and motors, but if everything else is in order, you should still get many thousands of cycles before a failure would become likely.
Okay, Here is what I do know; using 2 multi-meters I find my resistance between the input of 110 v lines is ~ 1 ohm, and at times ~ 0.5 ohm. this test is done with capacitor removed and start circuit off (and on, makes no difference). The resistance of the start circuit which is actuated by the centrifugal switch is closer to what is correct or 11 ohms for a 19 amp max draw when I test it separate from the rest of the circuit. I can not find a wire diagram for this motor to see why I would get such a low reading on the main 110 leads going into the windings. Earlier post I mixed 220 vs 110 max amp draw... 110 max amp draw for this according to Sta-Rite is 19.9 for 110 v.
Also, nothing in the internal wires show a lot of heat which would be the case with this kind of draw. I am not getting why my 20 amp circuit breaker did not pop with this kind of draw.
Am I missing something here? At this time I am thinking it is time to forget watering this year, save money and maybe next year we can get a replacement. Does my electronics as in computers and tiny motors experience fail me in this arena of large electric motors? I am having a really hard time with that possibility, I mean... Ohm's law is just that... ohm's law.
I thank everyone for their input.
Last edited by quazimoto; 11-18-2012 at 04:07 PM. Reason: add info
Once I can use my arm again I will reinstall old pump and get this straight.
Thank you to every one of you for your time, interest and info...
The Church, Spiritual Ctr & Retreat
St Petersburg, FL