Help on Imminent Failure

[nckingsret]

I have a 10 year old house with same age well and 20 gal pressure tank. I have never had a problem with it so I never paid much attention to it. Several days ago the water flow started to get interrupted for less than a second or so every 48 seconds. The water flow doesn’t cut out completely but the household pressure does drop. The tank pressure starts out at 58 psi, drops to 53 psi, and ultimately drops to 34 psi when the pump kicks on and the sudden short pause in water occurs. The tank fills up in seconds where the pressure is back up to 58 psi and the 48 second cycle repeats itself. The label on the tank says the pressure was preset at the factory at 38 psi so I would expect the pump to turn on at 38 psi and off at about 58 psi, though admittedly I can’t remember ever checking this. The water pressure doesn’t drop evenly over time; it stays above 50 for most of the cycle and then drops suddenly to 34 psi when the pump kicks on. The problem occurs on all outlets both inside and outside the house. There is nothing different about the water that I can detect. I’m not sure where to begin looking for a problem but is it safe to start with the pressure tank?

I would like to narrow down the problem before it fails completely and before I have to call someone for repairs. I’m mechanically inclined so I don’t mind doing some diagnostics. At the very least I’d like to rule some things out.

 

[Cacher_Chick]

A 10 year old tank is likely to have a ruptured bladder. I would check the tank first. Think of it like a balloon, even if it is not ruptured, it should be drained down to test and adjust the air pressure about once a year.

 

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[Reach4]

Cacher_chick is very probably right, and you have a failed pressure tank. Replacing that is going to get you going quickly and be better for your pump.

When you replace the tank, you would be better to go to a bigger tank. Get one with a diaphragm rather than a bladder for better life. Get Well-X-Trol brand for best life, but those do cost a premium amount.

With a submersible pump, normal operation is to have the air precharge set to 2 PSI below the cut-on pressure for the pump. With a jet pump, 4 PSI typically. The purpose of the differential is mainly to let the tank provide water between the time that the pressure switch tells the pump to go on and the full flow of water arrives from the pump. The other reason is to allow for a bit of difference between your water pressure gauge and your air pressure gauge. The reason to not go too low in air pressure is to avoid stretching the diaphragm or bladder too much.

So for checking the tank, first turn off the power to the pump, and open a faucet to let the water pressure go to zero.

Measure the air pressure with a tire pressure gauge, and record that. If water comes out, replace the tank. You can work around a failed bladder temporarily by adding air while there is water in the tank, but that would be a frequent chore and I don't know how to get that right. If the air pressure is above 10, I would just try adjusting the air pressure.

The symptom that points most strongly to a bad tank is the pressure jumping up to 58. The pause in pressure initially sounded like the precharge air pressure was too high. But that jump up in pressure pretty much confirms the tank failure, so maybe that air pressure checking is a waste of time. Its quick and free, however, so no big loss.

That 48 second cycle is interesting. Now is that with water being used at a pretty fast rate, or is that even if you are not using water?

 

[MI Well Drilling]

A wise valve guy once told me that the best way to fix this issue is by putting in a cycle stop valve. You still need a bladder tank but a cycle stop valve will give you more consistent pressure.

 

[nckingsret]

The 48 second cycle is with water being used at a fast rate. With the water off there was zero change in pressure measured over several hours.
It looks like the problem was the pump pressure tank switch. I had this replaced and it seems to have solved the water pause issue. The old switch had a decent amount of iron sediment in it that fell out when removed. Maybe switch would still be good but at that point I'd rather just replace it. The new 30/50 PSI switch seems to work fine with the inline water pressure gauge reading 30/50 PSI as well. The air precharge was set to 3 PSI below the cut-on pressure for the pump. Is this ok or am I asking for problems?

 

[Reach4]

The new 30/50 PSI switch seems to work fine with the inline water pressure gauge reading 30/50 PSI as well. The air precharge was set to 3 PSI below the cut-on pressure for the pump. Is this ok or am I asking for problems?

With a submersible pump, normal operation is to have the air precharge set to 2 PSI below the cut-on pressure for the pump. 3 PSI is close enough. If you have a submersible, you could raise the pre-charge a bit, or do it when you check the pressure 6 months from now. I go over a year between checking air precharge until you know your tank maintains the air pressure well. But initially consider the 6 month interval for at least for the first check.

If you have a jet pump, leave it where it is.

A momentary stutter in pressure because the precharge is set a little high is not harmful. You are not experiencing a stutter, so your precharge pressure is not too high for your system.

 

[nckingsret]

I have a submersible pump. I will check the pressure in February now that I've learned a lot about this.
So far I have been running different water outlets constantly this afternoon with no problems. I can barely see when I think the pump kicks on from inside the house, but I really have to stare at it to try and see it. I was told that it is normal to have a very momentary 2-4 PSI drop in water pressure inside the house when the pumps turns on. Does this sound right? I may be obsessing about this at this point but I just want to be sure I am not missing anything.

 

[Reach4]

I was told that it is normal to have a very momentary 2-4 PSI drop in water pressure inside the house when the pumps turns on. Does this sound right?

I don't think it is a given. If you see a momentary plunge by 3 psi, I expect the actual dip may be more due to ... and it could be less due to an overshoot by the mechanical meter. If you cannot detect the dip if you are not looking at the gauge, don't worry about it.

If you see a dip, I expect that reducing the precharge by 1 PSI, I expect the dip to reduce or go away.

I don't see it as obsession. More of a desire to optimize and understand.

 

[nckingsret]

OK, this ISN'T fixed as I had thought. The 'fix' only lasted for a few hours.
Now, what I have is a pump that is turning on at about 45 psi, pumps up to 50 psi, then stops, after having a new 30-50 pump pressure switch installed. I now get the pause in water supply much more often, say every 20-25 seconds. I saw the pump turn on at 30 psi and off at 50 psi 4 days ago.
I turned off the pump, opened all the faucets, and checked the air pressure in the tank using 2 gauges. The air pressure reads about 41 psi. How is this possible? I am pretty sure the air pressure was set to 27 psi 4 days ago. What's also weird is the water pressure gauge at the tee reads about 40 psi.

 

[Reach4]

I turned off the pump, opened all the faucets, and checked the air pressure in the tank using 2 gauges. The air pressure reads about 41 psi. How is this possible? I am pretty sure the air pressure was set to 27 psi 4 days ago. What's also weird is the water pressure gauge at the tee reads about 40 psi.

This part could be explained if the water pressure was not drained to zero, but is indeed about 40 PSI at the pump. Did you turn off the power to the pump, as you should have, or did you close a valve? If you did turn off the power, and did not close a valve, and the open faucet(s) ran water until the water was exhausted, you cannot have water pressure.

I would wonder if the nipple to the pressure gauge was clogged, but the air pressure reads about what you would expect if the water pressure was indeed 40 psi. So why didn't opening one or more faucets drain the pressure? You probably have a drain at the base of the pressure tank. Maybe use that to drain. Hooking up a hose before opening that up saves a mess.

 

[Valveman]

If the air pressure in the tank increases on its own, the bladder in the tank is bad.