Pump chatter/surge at pressure switch

I noticed an issue with my 3-1/2 year old well about a month ago. I have a 400' deep well, with a Goulds 7GS10 1 HP submersible pump.

Intermittently, when the low cut-on pressure of 40 psi was sensed by the pressure switch, activating the pump, an audible surge/chatter was occurring at the pressure switch with the contacts cycling back and forth. It almost sounds airbound. I replaced the 40/60 pressure switch and while doing so made sure the air pressure in the expansion tank was set correctly (38 psi) after draining down the system.

If running the water when pump comes on now, the water pressure in the house drops to zero. The only way to overcome this is to shut the open faucet/valve and wait for a few seconds. Turning back on and everything is fine. Mostly happens with hot water.

I tried another switch since I thought that one might be defective and verified the nipple is cleared of blockage.

I was reading about upthrust usually caused by defective check valves. Is this possible? Any other thoughts?

I am new to this forum but from what I read, it seems like this is the place to go for advice.

Thanks

Where is the switch in relation to the pressure tank? What does the switch hook up to the rest of the plumbing with? What brand of switch?

bob...

New switch is a Flotec brand from Home Depot and it hooks up to a 1/4" straight nipple. The nipple attaches after the check valve located near the tank at the "T", which is where the main line into the bottom of the tank goes in/out. The pressure gauge is to the right of the pressure switch and then I transition from either the 1" line down to the 3/4" main cold supply line for the house.

As I mentioned this is something that has just started recently. My pressure from faucets has always been good and switch has worked normally in the past.

Jason

Flotec wouldn't have been my first choice, but it should not be acting this way. I am not sure why you have a check valve at the tank, but that might be the problem. It shouldn't be there anyway if you have a bladder tank.

Try removing the check valve and see if that doesn't cure your problem.

bob...

Thanks Bob.

I was actually going to replace the check valve but if it is not needed, then even better.

As far as Flotec...it was acting up with the original Square D which prompted me to change it in the first place. Is this possibly up thrust due to a faulty check valve midspan on the line?

I will keep you posted.

Jason

Upthrust is what happens to an impeller stack in a submersible pump when the water level is very high and there is no backpressure on the impellers. This can cause wear on the impellers and bowls. I think your check valve is hammering open and causing your water hammer which will double clutch the switch.

bob...

Before doing anything I would increase the pressure in the tank by about 5 pounds and run a few cycles. Between the errors in consumer switches and gauges and air fill gauges, one can have huge variations in the desired range.

If I increase the air pressure in the tank, shouldn't I increase the pressure at the switch also?

You are right about air gauages. I have 3 different gauges that read +/- 2 psi.

To Bob: I think you are right about Wtaer Hammer. This morning when the pressure was lost during my shower, I heard a bang resonate through the pipes when the wtaer broke free. What is the cause of Water Hammer and what is the best way to tame it?

Thanks.
Jason

No, do not increase the pressure switch setting. You have nothing to lose by increasing the tank pressure but a bit of drawdown. Its a cheap experiment that might be your solution. Consider it a part of the process of getting the poltergeist out of your pipes.

That bang is probably that check valve opening. Try removing it and I think your hammering will disappear. You may now notice (after removing the check valve) that you have water going back down the well due to a hole in the droppipe or a faulty check valve in the pump. The above ground valve has been masking the real problem.

bob...

Bad news today...the pump will not fill the tank anymore. It may be a defective switch. I bypassed the switch and hooked the wires directly and it worked fine. I have a well guy coming tomorrow am.

Tonight we have no water!!!

The chattering probably took the points in the switch out.

Hopefully the driller will get you going again.

bob...

And have that check valve at the tank removed. If you have any problems without this valve, then have the pump pulled and either replace it, the check valve on top of the pump, or the drop pipe or the under ground pipe from the well, depending on what they find. There should not be any check valve above ground on a sub pump, and if any well servicer argues otherwise, find some one else to do your repair. That check valve is like using a band aid to stop the bleeding when your leg has just been severed.