Well pump short-cycling w/ no visible pressure tank.

[Triple]

Well pump short-cycling w/ no visible pressure tank.

Semi-experienced but not professional DIY-er here. Have done a lot of plumbing work over the years, many various repairs and renovations, but never any pump work.

Our well pump was installed about 18 years ago just before we purchased our property. I don't know anything about it-- manufacturer, capacity, etc-- except that it has performed flawlessly up until this last fall, when it started cycling on/off much quicker than it ever had before.

I'm finally digging into it and cannot find the most likely culprit for this symptom, a failing pressure tank. I know that buried tanks and in-casing tanks exist, but the local pros I've talked to say they've never actually seen any around here. They think this system has been running all these years without a pressure tank.

Is that really possible? Professional opinions appreciated... if there's a tank in here somewhere-- especially a buried one-- I don't know where to look for it. The whole idea of using a buried tank for this system also seems very stupid to me.

I'll be replacing the burnt up pressure switch this weekend just to rule it out. If there is no tank in this system, what else could be causing the short-cycling besides the pump itself? It only cycles on/off when a tap is running somewhere, never when the taps are closed, so I'm doubting an internal leak somewhere.

We are not really experiencing low water pressure. It just goes from normal to high over and over again.

 

[Reach4]

Replace the pressure gauge too.

Are you implying that an outdoor pressure tank would not freeze?

 

[Sponsor]

 

[LLigetfa]

How much water can you draw from when the pump has shut off to when it turns on? That amount is your drawdown and if it is much more than a cupful you have a tank somewhere. Mind you, a drawdown test is not conclusive since the tank could be badly waterlogged.

As to why it would be buried, obviously there is no room for it inside that small concrete cistern at the wellhead.

 

[Triple]

How much water can you draw from when the pump has shut off to when it turns on? That amount is your drawdown and if it is much more than a cupful you have a tank somewhere. Mind you, a drawdown test is not conclusive since the tank could be badly waterlogged.

If a tap is open full blast, the pump cycles on and off every several seconds. It's powered on for two or three seconds, powered off no more than ten, over and over again. There is 80-ish feet of pipe between the well and the house, however (and I have no idea how deep it is).

Is there a way to identify an in-casing pressure tank without major disassembly? Every diagram I've seen shows such tanks 10 or more feet down inside the casing.

As to why it would be buried, obviously there is no room for it inside that small concrete cistern at the wellhead.

That's just a section of concrete pipe sitting on the ground around the well casing. Every well I've seen in this area (besides mine) has had an insulated outdoor "pump house" containing the tank, switch, etc, which would be just as easy to construct as it would be to bury a tank, and far easier to maintain. Especially here in north Georgia, where the ground is 75% clay and 25% rock.

 

[Reach4]

If you have a buried tank, I would expect it to be fairly near the pressure gauge on the line of the pipe to the house. A septic tank probe could let you probe for it. https://www.homedepot.com/p/Bully-T...tyle-Handle-and-Sharpened-Tip-99202/205348126
I have not tried it. I hope the probe would not penetrate the outer shell of the buried tank.

 

[WorthFlorida]

Dig down on until you see which direction the pipe to going to the house, then start probing the ground with a pitch fork, or get a metal detector. What is not seen is a check valve. The submersible pump probably has a built in one.

It has all the symptoms of a failed pressure tank as you suspect. If you need to give up on the search, add a new pressure tank right at the well. You should look into CSV, cyclic stop valve. You only need a small pressure tank, however, you'll need to protect it from the occasional freeze in N GA,

Constant Pressure Pump Control Valves

Constant pressure pump control kits, constant pressure pump control valves, and pump monitors

cyclestopvalves.com

 

[Valveman]

Yeah you either do not have a tank or the tank has failed. Most likely there is a tank somewhere or the pump would not have last a few weeks cycling on and off like that. Right off the side of that well head would be a good place for the PK1A with the 4.5 gallon size tank. It would be an easy install. With the CSV and switch in this location it won't matter if there is a failed tank somewhere in the line unless that tank starts leaking.

 

[Triple]

There was indeed a pressure tank down there. In the ground she stays.

 

[Reach4]

I think you will want probably to replace that failing/failed tank.

If you can up the air precharge, you might get some more time out of the existing tank.

The ones made for underground cost a premium. https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=well-x-trol underground

When you fill things back in, you might consider some sand for easy future digging.

 

[Fitter30]

Last pic what is that after the supply tee top of pic. Looks like could be the ex tank.

 

[Triple]

I think you will want probably to replace that failing/failed tank.

Replaced the original set-up with a PK1A kit from Cycle Stop Valves.

Pressure was up and down and wonky for a little while after start-up, which I assume was air working its way out of the system, but now everything appears to be working as-advertised. The short-cycling has ceased and hopefully I can extend the life of this beat up old pump (though I realize the last few months have been very hard on it).

Next project is building a small, insulated shed of sorts around it. Maybe some extra electrical for a small emergency space heater. And yes, I know my plumbing is crooked... I had to cut out a slip joint that leaked horribly upon start-up...

I'm also considering the possible advantages of adding a second tank somewhere in the system, and/or replacing the current one with the larger 10 gallon alternative.

 

[Valveman]

Nice job! A little crooked usually doesn't hurt anything. But I am afraid the first elbow maybe under stress and could give you a problem. Could add a short piece of pipe and two couplings to the pipe before it goes underground to square it off. But it won't make any difference on how it works.

After seeing how the CSV works you will understand there is not a lot of advantage to a larger tank. But it looks like the 10 gallon tank would fit in the same spot if you wanted. You could also add another tank anywhere in the system like on top of the water heater.

 

[Triple]

After seeing how the CSV works you will understand there is not a lot of advantage to a larger tank. But it looks like the 10 gallon tank would fit in the same spot if you wanted. You could also add another tank anywhere in the system like on top of the water heater.

Correct me if I'm wrong, of course, but I thought a larger tank (or multiple tanks) would help with low-flow situations. Frequent hand-washings with small children, a low-flow kitchen faucet for doing dishes, etc may not produce the flow necessary to even activate the valve, at which point the system will basically be behaving conventionally, yes? Draining the tank, kicking on the pump to replenish it, then kicking off at 60psi, then repeating... under which conditions a small tank is actually a disadvantage, because it is causing the on/off cycling the system is designed to prevent, correct?

In higher-flow conditions like showering, filling the washing machine, etc, the small tank is appropriate, but we have a lot of low-flow situations in our household.

And yes, I plumbed this this arrangement a little high so I'd have space for the taller tank later on.

 

[Bannerman]

the system will basically be behaving conventionally, yes?

No. A conventional system will fill the pressure tank at the maximum flow rate the pump is capable of delivering, When water consumption is less than the pump is capable of delivering, water will flow to the fixture/appliance that is utilizing water, and the excess capacity will flow to the pressure tank until the system pressure rises to the pressure switch cut-out pressure.

A CSV in the other hand will limit the fill rate to the pressure tank to 1 GPM. Since a 4.5 gallon pressure tank will hold a little more than 1 gallon water, the pump once activated would therefore need to run for a minimum 60 seconds to add 1 gallon water to the pressure tank.

"A minimum 60 seconds" is stated as water use is seldom limited to just flushing a toilet since flushing a toilet is usually accompanied by washing hands or activating a shower. When additional water is consumed within 60 seconds of the pump becoming activated, the additional water demand will extend the time for the pressure tank to fill, therefore extending the pump's run time.

When water consumption exceeds 1 GPM, the pump will continue to operate without cycling for the entire time water continues to be consumed. Once there is no further flow to fixtures/appliances, the CSV will again restrict the flow rate to 1 GPM to fill the pressure tank.

 

[Valveman]

Thanks Bannerman. I wish I had a nickel for every time I have had to explain that in the last 30 years. With the 1 gallon stored in a 4.5 gallon size tank, using a 40/60 pressure switch with the CSV set for 50, there is only about 30 seconds of run time to fill the tank. But that is only after the last tap has been closed and you are finished using water. 30 seconds is usually plenty of time for the pump to time out, waiting to see if anyone, anywhere else in the house starts using water. As Bannerman said, if anyone, anywhere else in the house starts using water before that 30 seconds is up, the pump just continues to run and does not cycle off.

The extra gallon in a 10 gallon tank, or even the 5 gallons stored in a 20 gallon size tank doesn't last long when a tap is opened. When using a CSV, the extra gallon or two in a larger tank is not very helpful in supplying more water before the pump starts, but rather to increase the time delay before the pump stops, making sure everyone is finished using water before the pump shuts off.

Yes, with only 1 gallon in the pressure tank the pump will cycle on when a single toilet is flushed. However, the CSV will make sure the pump stays on until you are finished washing hands, taking a shower, washing machine is full, etc. With the 4.5 gallon size tank the CSV will make sure the pump stays on for another 30 seconds after the minute or so it takes for the toilet to fill. During this time before the tank is full, if anyone, anywhere else in the house uses water, the pump just keeps running.

The more people in the house, and the more times water is used, the less likely the pump will go off. In houses with multiple people, the pump usually comes on when people start waking up, and just stays on until everyone is finished using water and out the door to school or work.

The fewer people in the house, and the fewer times water is used, the fewer times the pump cycles anyway. If you are the kind of person who turns off the tap you are soaping your hands, you won't use a cup of water to wash, and maybe 3 cups to brush your teeth, and the pump won't even come on. If you are the kind of person who leaves the tap running when washing hands and brushing teeth, you will use a lot more than 1 gallon of water and the CSV will just keep the pump running until you are finished. If there are both kinds of people in the house, the CSV will take care of both of them without cycling the pump.

Here is a chart made by one of my customers on the difference in the number of cycles with different size tank, with or without the CSV. Of course the pump will cycle a few times less when the CSV is used with a larger tank. But the number of cycles caused by the CSV even with the small tank is less than the number of cycles with a larger tank and no CSV. What it boils down to is that there is really no way to cycle the pump too much with a CSV and a small tank no matter how you use water.