Presure switch design issue

I had to have the pressure switch / pump relay assembly on my well pump replaced today. The old one was about twoyears old and the contact points were BADLY burned. The repair guy said this was not unusual and that he frequently has to replace this part after a few years. He said some places have to replace them every year or so.

Is this normal??? It seems rather archaic to me. Does anyone make sensor / switching modules that don’t arc them selves to death? I am surprised I could not find any solid state or zero-voltage switching systems that would eliminate the arching issue.

If no one manufactures one, I may build one myself.

Thanks

Check out Murphy switchgages. They have a lot of water pressure setups. You might also read the specs on your switch and make sure that it is rated for the horsepower of your pump.

I had a situation once that I had a larger horsepower pump than I did a pressure switch. The switch points kept welding shut. I used the pressure switch as a relay. I ran 110 volts through the pressure switch and used a magnetic starter contactor with a 110 volt coil to start the pump. We are a Valley irrigation dealer and have access to many starter contactors. This worked pretty well and could be done if you understand motor controls.

I am not sure if this setup would work for you or if it really is a better solution than a pressure switch alone.

I would be more inclined to think the tank is waterlogged. This is what generally burns points. Or as rshackleford stated, make sure the switch is rated for the horsepower pump your using. Most standard switchs are rated for 1.5hp. The larger ones for 3hp. Beyond that, you would be using a contactor operated by a switch.

When this guy said he see's this all the time, it makes me wonder if he doesn't have a lot of stock in Square D.

A good pressure switch can last for many years.

bob...

You’re saying that the rapid cycling on and off will ruin pressure switches. Does this cause the points to char and make poor contact or does it cause the points to weld shut?

I have also seen stitches in places like well pits with high humidity corrode and lose continuity.

Yes, cycling will burn them pretty badly. Since the motor draws about 5 times the amps to start, and if the starting is happening quite often, the points tend to heat up and pretty soon they are just not going to make a good connection anymore. The plastic that holds the points can get hot enough to cause problems also.
The welding shut is usually from a major spike from lightning or a power surge from the power company. A bad ground could cause them to weld also.

I have seen a bunch of them just plain burned to a crisp and couldn't explain why they did. Nothing else was damaged in the home, but the pressure switch the cover and all wires were just a melted blob. I would imagine loose wires could cause that to happen.

I live in Florida and am used to high humidity but cycling is the biggest problem. It's hard on motors too.

bob...

I recently serviced a well that had an old galvanized pressure tank. The tank had not air and the pump was cycling rapidly. Well, this is what we found once the pump was replaced. We found that the splines on the motor were rounded off. I have seen this happen with certain types of water that is so corrosive it even starts to work on stainless, but this water was pretty decent water. I have a feeling that this cycling aided in the failure of this motor. In addition to this, the pump was a Sears pump and the bearing were pretty ruff in it, I don’t think that this helped much either.

It seems like people don’t catch onto pressure tank problems until it is too late. I wonder if Franklin’s Pumptec would shut down on rapid cycling. Perhaps that product should be promoted more.

I'm not sure if the PUmptec checks for cycling or not. I'll have to check that one out.

Cycle stop makes a device that does just that and also looks for low amp conditons like dry well problems and can be set very precicely.

I know Red Jacket had a problem with their splines a few years back when they were still making their own motor.

I also know that cycling can cause the rounded spline problem you mentioned. Of coarse if the winding out lasts the spline, so what?

bob...

I had a situation where the pump burned out pressure switches every few weeks. This is on a jetpump.
The owner finally called me because he was tired of installing new switches.
The pump and tank, along with a filter housing, was installed in a very cramped space. The discharge piping had more elbows in it than a room full of people. The longest straight run was about 12". I cleaned it up as much as possible, but the switch still "chattered" on cutin and cutout. I relocated the sensing line from the pump head to the outlet side of the pressure tank. While this helped somewhat, it still didn't alleviate the "chatter" completely. I then installed a Sq. D Type G pressure switch, one designed for industrial pumps and compressors. It came factory preset at 30/50. That was 14 months ago, and no more problems.
Ron

I had one similar on a submersible. 5hp 3 Phase. When this thing would start or stop, it hammered the switch. We moved it all over the place. No help. The only thing that worked was the little switch plug that goes in the female opening in the bottom of the switch. It has a hole in the middle about the size of a pin head and I'm sure will plug up some day. But for now, no more burned points, or motors.

bob...

We do a lot of pump controls on center pivot irrigation systems. A person could get really fancy and use an on delay timer. Use any pressure switch as a relay to close a circuit to the timer and have the timer energize a coil on a contactor. Set the time to five or ten seconds. This would eliminate the chatter.

The downfall to this would be more things to go wrong for the customer.

Better hope the next guy to service the pump can understand what you were doing!

Hopefully there won't be any next guy. I'de like to think my customers are loyal.

I know.... I'm just dreaming.

bob..