Pressure tank losses pressure for 5-10 seconds

Hello, I'm new to this forum. It looks great.
I have looked at a lot of similar questions but didn't find one that seemed to address my issue. If I missed the answer, I'm sorry. So here is my problem:
I have Gould pressure tank and a well pump that is 580 feet below grade with water backfilled to 185 feet below grade. When the pressure drops to the trigger point 35-38psi the pressure gauge bounces a bit then descends to near zero and quickly (about 5-10 seconds) goes back to roughly 35psi and starts building pressure as it should. My wife first noticed the water stops or almost stops for 5-10 seconds. It happens every time the pressure drops to the trigger point. What should I do? Thank you.

Shut the pump off, open a faucet until the water stops (won't take long), leave it open. Then, measure the pressure in the tank. My bet is that it is zero. You might also get some water out of the air valve which is a sure sign that the bladder is shot. If there is no air compressed by the pump in the bladder tank, you're trying to compress the water, which doesn't and you are stretching the pipe and hoses. They don't give much, and when you open a faucet, the pressure drops to almost zero instantly and it takes the pump a moment to build it back up. If the bladder was working, it would drop gradually from the 55 down to the turn-on point, and still have a little water under pressure to take up the slack while the pump does its thing.

Your tank is running out of water before the pressure switch is kicking in, if it has always operated like this then the pressure in the tank, when empty, is set too high, if this is new problem then it may be a pressure switch problem.

Reduce the pressure in the bladder tank a few pounds and see if that takes care of the problem.

Rancher

Thanks for the advice.

I let some air out of the tank to reduce the pressure by about 2 psi. No sign of water. Don't think the bladder is shot because it restores pressure properly and the problem doesn't repeat until the pressure drops and that takes quite a bit of water use. Don't have the results of reducing the pressure yet. Will let you know soon.

Thanks again.

Bill, drop the air on the drained tank to 1-2 psi below the cut in of your switch, and the problem should go away

When I have had this problem, ADDING air so static tank pressure is about 2+ PSI above switch setting solved it. This is exactly the reverse of Ranchers advice, so try both and report back.

If your air pressure gauge and the water pressure gauge are accurate, then the suggestion of raising the tank's static pressure to be above the cut-in pressure won't work. If the gauges aren't accurate, the reading you need could be anything.

The operational idea is that the tank should still have a little water in it when the pressure switch turns on the pump at its low-pressure point. If the tank actually has emptied prior to that time (as would happen if the air pressure was higher than the cut-in pressure switch), then you'd have a moment of no water as the water pressure collapsed from okay to zero when the water ran out.

Air pressure gauges and water pressure gauges can easily be off from each other.

A way to check is to take the air pressure in the tank when things are stable and compare it to the water pressure gauge reading. That will tell you the difference between your two gauges for future reference.

A sliding stick type of air pressure gauge can be quite inaccurate, especially as they age. A digital can be too, but they are often more consistent over their life.

I agree with the two pounds less, not the two pounds more. But with it taking 10 seconds to get water back, it would seem to me that the droppipe in the well had drained back. Do you have a check valve anywhere near this tank in the pipe feeding it from the well?

bob...

Wow! Great responses.

I didn't expect to get so much info. I lowered the pressure and it seemed to help at first - very subjective observations. Problem still here or has returned. I like the idea of knowing the difference between the air pressure and the water pressure gauge reading. I'm going to let some more air out of the system to make sure it's below the "cut in" point. I'll let you know about the results. I'll also look for a check valve. When I was thinking about this, I thought it sounded like water from the pump was not immediately ready to enter the tank when the pump gets turned on. But wouldn't that put air in the tank? And if it does, wouldn't that show up at the outlet like other air in the system?

Thanks a lot everyone.

I'm off to work on it now.

If a next step is needed, is it safe to turn off the pump and empty the water from the tank to get a minimum air pressure reading? Do I have to do anything special when turning the pump back on?

Thanks again.

In order to check the tank pressure, you MUST drain all pressure from system. In other words, turn off the power and open a faucet until the water stops flowing. Now check air pressure in the tank. The air pressure should is seperate from the water pressure if the tank is still good.

I think you will find that check valve when you get home.

bob...

Less pressure same problem

It's great you guys are sticking to this with me. I really appreciate it.

I reduced the pressure some more, but problem remains. I looked for the check valve and found it right next to the pressure gauge. The air pressure is about 49 when the water pressure is 50. That seems good.

I have noted some more exact info about what happens at the tank when the pressure drops.

when pressure drops to about 30lbs there is a click.
then the pressure drops to zero pausing a few times on the way.
then it stays at zero briefly.
then the pump starts and pressure increases to maximum pressure.

Does this help determine what I should do?

Thanks again.

Yes, quit letting pressure out of the tank. You haven't checked the pressure in the tank like the guys are telling you to. Read the earlier posts on how to do that.

So you found the check valve. This is the reason there is a hesitation after the switch points close before water starts flowing again. Your pipes are draining back due to a leak somewhere on the pump side of the check valve or you have a bad valve in the pump. Either way, you need to pull the pump or find an underground leak to remedy the problem.

bob...

I had the same problem and it ended up being (A failing pressure switch also check your whole house filter if you have one it also can cause a pressure loss at low pressure and you will get it back as the pump pressure builds which can seem like a delay.) I replaced both the switch and the whole house filter for under $20 total and my pressure switch was only 11 yrs old I would think it would have lasted longer??

Also set your pressure tank up like the guys are telling you it is the easiest way to get it right

1: Check and record your cut in pressure setting by watching the gauge when the contacts close.

2: Shut off pump

3: Drain water out of tank by running faucet from the lowest point possible best place is at the tank valve if you have one but any can work

4: After pressure loss and no water - set tank air pressure 2 to 5 lbs lower than the tank cut in pressure setting. Use a low volume pump like a bicycle pump.I don't suggest you use a compressor but if you do be very careful.

5: Close any open faucets or valves

6: Turn on pump to refill and recheck cut in pressure setting

You may just want to replace the pressure switch at this time when the tank is drained and the pump power is OFF to keep from having to do everything twice. just set the tank pressure to 2-5 lbs under the new pressure switch cut in factory setting .

I sincerely hope it works out for you, it requires a little time to do it right but the piece of mind once you have set it up right and it works is all worth it.

Hopefully you have solved your problem by now, but if not maybe I can help.


You say:
when pressure drops to about 30lbs there is a click.
then the pressure drops to zero pausing a few times on the way.
then it stays at zero briefly.
then the pump starts and pressure increases to maximum pressure.

This is the key. Your switch is closing at the proper time (30#) but the water is not getting to the tank before the tank goes empty. This pretty much eliminates air charge or pressure switch problems.The only real explanation for this is a leak between the system check valve and the pump intake. It could be a bad check valve in the pump or a hole in the drop pipe (580' well probably set on galvanized pipe or schedule 80 PVC). It could also be a broken pipe in the distribution system if the check valve is located at the tank.Take the pipe loose at the well and check for a lag time between starting the pump and water starting to flow. My guess is that the water level in the pipe is dropping down to static water level and causing the lag. If this is the cause, your pump must come out, 580 feet usually requires a pro. Any sign of air in the system? Most leaks of this type will pump major amounts of air into the tank.

MMWS