I am on a well for my water. I have recently started experiencing this problem. When I turn on any faucet the water pressure is fine. After about 3 - 5 minutes the water pressure suddenly decreases to 0 over about 4 - 6 seconds the after about 1 second goes back up to full pressure. This happens, hot, cold or mixed temps.

 

Sorry. I should have added that if I leave the system on it just keeps repeating this cycle. I had my son turn on the water while I sat near the tank. When the pressure reaches 0 the pump kicks on. Maybe I should be saying flow instead of pressure. The gauge never fluctuates.

 

Sounds like you have too much air in the pressure tank. The air pressure in the tank should be set at around 2-3psi BELOW the cut in pressure of the pump. If it is above the cut in pressure, then the tank will completely empty of water before the pump starts up. Since the air behind the bladder cannot push on the water OUTSIDE the tank, the pressure drops to zero. Soon, thereafter your pump will kick on and give you back some pressure but this cycle will continue.

To measure the air pressure in the tank you need to empty the system of water and keep a tap open. If your pressure tank does have too much air, then just release some till it gets to the right level. If the air pressure is correct, then it is some other problem.

 

I don't think it's a pressure tank issue. Regardless of the tank charge.... the pump should come on way before 0 psi.

Two things come to mind.... defective pressure switch or a restriction in the little water line that feeds the pressure switch. Many times a 1/8" piece of pipe is used and it rusts closed.

 

It also might be a pump failing. When that happened to me I could see the pump locking up by putting a clamp on meter to measure amp draw. Amps jumped to 24 from a normal 12.

 

Good point.


Then a pertinent question would be...... does the switch actually turn on when the pressure approaches 0psi or is that when the pump starts running.

 

Yup, run the water and watch/listen to the pressure switch. If the pressure switch stays closed and the pressure drops to 0 then you should next look at the pump.

 

I would still check the air in the tank. I agree 4 to 6 seconds is a long time to sit at zero but if the pump was short cycling for 4 to 6 seconds before water re-enters the tank, due to a collapsing diaphragm, he might not notice that condition with a submersible pump.

He stated that it seems to happen after about 3 to 5 minutes with a tap on. Probably the amount of time it take to empty his pressure tank.

Anyway the other ideas are certainly good ones as well.

 

How do I find the cut in pressure of the pump?

 

If you have a pressure guage on your water system, then simply watch it while you are running some water. The pressure will decrease as water leaves the tank. At some point the pump will cut in (turn on). You may hear the switch click or you will see the pressure in the system start to rise. The low point on that pressure reading would be your pump's cut in pressure.

Whatever the number is, turn off the pump, empty the water from the tank by opening up a tap at the lowest point in the house. Leave the tap open and measure the air pressure of your pressure tank. That number should be at least 2-3psi below the pumps cut in pressure for the system to operate properly.

The pump switch/pressure tank system is designed so that the tank always has some water in it, at all times. As the tank gets fairly empty the reduced pressure turns on the pump and it refills it. If the air pressure is higher then the pumps cut in pressure, it means that the air will push out ALL the water from the tank before it turns on the pump. The pressure tank can only exert pressure on water in the tank. Since the diaphragm of the tank gets stopped at the exit hole of the pressure tank, once all the water is emptied from the tank, all pressure in your house will be momentarily lost, until the pump kicks on and refills the tank. Since some tank diaphragms get caught inside the exit hole, so to speak, when the pump kicks on you can sometimes get a few short cycles (pump on-off-on-off) until the diaphragm gets released and allows water to re-enter the tank.

It is this condition or simply the loss of pressure when all water exits that tank, that you may be experiencing. Or not, but it is fairly easy to check.

 

The cut in pressure is the point where the pump is supposed to start running. Could be 30 or 40 psi depending on model of pressure switch.

 

Clarify this--are you saying the pressure gauge never varies but the flow stops? In that case it sounds like you do have a plugged port to the gauge & switch.

 

I agree with guy....at the very least, the 1/4" ?? pipe that runs from 'T' to gauge needs to be replaced...since the gauge and pipe are so cheap, swap them both out, unless gauge is brand new...
It doesn't fix your problem, but it will give an accurate reading, and shed light on why your getting flow and then no flow.
If gauge is frozen because of plugged pipe, then it stands to reason, the pressure switch may be partially plugged too...and that could be your problem.