Pressure switch bounces on and off when disengaging

I had a square D well pressure switch that was old and started to leak. So I put in a new switch. The problem now is when the switch reaches the cutoff pressure and shuts off, it bounces, or opens and closes the contacts several times (usually 2 or 3 times then stays off). This causes power pulses to the pump, which can't be good for it, and lots of noise. I thought it may be a bad switch, so I replaced it again, but still with the same result. The only way to make it stop is to increase the cutoff pressure, way beyond where it should be. The switch is at the pipe where it comes in thru the wall from the pump, the storage tank is across the room on the other side of the basement. Would a "water hammer arrester" fix this? If so where should it be placed, near the pump switch or by the tank? Or would a check valve near the switch fix this? It was never a problem with the old switch, and Im tempted to put it back in even though it leaks. Thanks for any help or ideas on how to solve this problem.

Check your storage tank's pressure...the bladder may be shot. Does the pump turn on very shortly after opening a valve?

THe air pressure in the tank should be checked with the pump off and the tank drained.

With some of the reading Ive done here, I think you need to move your switch closer to the tank. This is just my guess.

The old switch leaks because it beat itself to death, broke the diaphram and thus added some play or relief to the hammering - homemade surge protection.

My guess is that your new switch will do the same soon [ if the pump and pipes hold ] unless you get some air into your storage tank. A water hammer arrestor is just a sealed captive air tank anyway. But its not what you want unless its in the 80 to 100 gallon size.....

The switch needs to be by the tank to work properly.

And your right, that hammering is definately not good for the motor or pump.

bob...

All of these are valid points. Except that the system worked just fine for many years as it was set up. No hammering at all. The only problem is that after many years the switch started to leak, but I don't think it because it beat itself to death, just from old age. The hammering only started with the new switch. The tank had a bladder that was operating and pressurized fine, but the new switch still bounced. It was so annoying that I would increase the cutoff pressure a little to stop it, and then it would be fine a few days, and then start up again. So not wanting the pump to stutter like that, I would raise the pressure a little more, until the result was that the pressure became too high and the bladder has now burst (insert laughter here). So now I need a new tank, but want to know how to stop this switch from bouncing so it doesn't all happen again. It would be possible to move the switch over by the tank, but very difficult, since it would need to be rewired on the other side of the basement. And I will do that if it is entirely neccessary, but I don't understand then why everything would have worked fine up until now as it is. There is a pressure gauge next to the switch. When the switch kicks off the needle swings quickly from side to side, the fluctuations causing the switch contacts to open close several times. It almost seems as if the switch needs a mini shock absorber on it, so it can move slowly but not able to bounce.

I don't think there is that much difference in pressure switches. Even if you bought one of the big box elcheapos. They all work the same way.

The gauge moving up and down is what water hammer does to your pipes. The tank is taking the shock out of the system, but since it is so far away from the switch. The switch doesn't know it right away.

There are little plastic devices that are inserted into the female fitting on the switch. They have a pinhole that keeps the pressure differences away from the diaghram on the switch long enough for the pressure in the pipes to stabilize. But they plug up quickly and are more trouble than they are worth.

bob...

You don't need to move the switch across the basement, only the sensing line. That way you don't need to move the electrical too.
Ron

Not sure what you mean by only having to move the sensing line, not the electrical. If the tank and bladder acts as a hammer absorber then I need to have the switch close to it so it won't bounce around, as is my understanding now. My tank has a bad bladder and I was reading on the side of it that the air/water seperator is replacable. Is this true and how hard is it to do? Where can you get another bladder? The tank is a Flotec 82 gallon "equivelent" not sure what the real gallon capacity is. I will probably move the switch over next to the tank too, and hope that solves the hammering switch bouncing problem.

Instead of moving the switch and the electrical, just move the pressure line going to the switch from where it is now, to the tank. Use 1/4" poly tubing or the like and some barb fittings.

The tank you have is probably made by Sta-Rite. They have replacable bladders. Most tanks don't have this feature because their bladders last a lot longer. Think about it. Do you want another one of these tanks?

I changed one bladder. I will never do it again.

bob..

I moved my sensing line....

Hi, I had replaced a Gould shallow well factory pressure switch (two years old, spring broke) with a Square D. I immediately got the same hammering condition in the switch. Based on what I read exploring this site, I soldered a tee in to the copper pipe near the pressure tank and ran a piece of 1/4 inch plastic line using compression fittings from that tee to the pressure switch inlet (about 3 feet). I added an extra length of tube so that it is looped , and installed it. I had to put a plug (another trip to hardware.....duh!) in the pump housing when I unhooked the factory line. It greatly improved the situation, but I think that since my pump is so close to the tank, I still get a little "chatter" once in a while. I am happy with my "fix".
Pumpman is right, by doing it this way I did not have to remove or mess with the pressure switch or the wiring, and that made it easier to do too!

If you crank up the pressure, it will help stop the chatter and so will spreading the pressures out. Instead of 20/40, 30/50 make it 30/60. This might stop it all together.

bob...

I call it reverse water hammer. Instead of slamming the faucet off and causing a shockwave in the pipe from the mass of the water behind it, the pump is slamming the water on and causing a pressure surge from the mass of the water in front of it. A local hardware store specializing in well water equipment sells a small plastic hootchie that slips into the base of the pressure switch where it mounts to the pipe. The walls are cylindrically shaped and the bottom is a hemispherical dome with a pin hole in the center. I can not find it for sale anywhere but it always does the trick without having to install a water hammer arrestor next to the switch, or install the switch next to the tank, or crank the pressure way way up. Next time a switch goes bad I'll use my imagination to see what I can dream up. A plastic dowel rod filed to the correct diameter with the drillpress and a small hole drilled through it might do the trick or something like a valve stem cap with pin hole and electrical tape wrapped around it for a firm fit. Maybe a piece of bicycle tube with pin hole or tightly wrapped window or pet screen would also work. Electrical tape wrapped around something to obtain a press fit should stay sticky when submerged and shoe goo glue you buy at Walmart should tack it in place if necessary. I'm sure there are many other possibilities that cost next to nothing and will work just fine. Someone should do a short concise YouTube flick along with other well water equipment tips.

Steve, I’m familiar with Square D’s Pulsation plug for their pressure switch. I think they look like a Sombrero, with the tip of the hat cut off. A FSG pressure switch can be ordered with the pulsation plug installed by adding a “P” to the end of the model number. A bag of 50 pulsation plugs can also be ordered, part #1530S6G1.

A pulsation plug or "snubber" is only needed when the pressure switch is in the wrong location or you have water hammer. Either way the snubber is just a band aid for some other problem.

Boycedrilling said:

teve, I’m familiar with Square D’s Pulsation plug for their pressure switch.

Click to expand...

I am curious how that attaches to a pressure switch. I find no photo or instructions.

I see Mouser offers quantity 1.

You just stick it up in the female fitting of the pressure switch before you screw it to the 1/4" nipple.