Pressure Drops to Zero

[PNelson1337]

Hello All,

This forum has been an absolute wealth of information for me & I appreciate all the contributors.

I had a pressure switch that failed (water started leaking out of it). The switch was replaced, but the system wouldn't keep pressure with use.. Recharged the tank, still the same issue. The pump would short cycle, or so it appeared. A few plumbers & online research pointed towards a water logged pressure tank or an issue with the tank itself.

My entire system is 50+ years old & the above ground stuff is 20+..including two worthless contact tanks. It was a good time to replumb the system & sort out my issue.. New pressure tank, tank t, etc..

Same issue as before......

The system will hold pressure as long as all valves are closed & there's no actual water usage. Once usage happens, it immediately drops to zero.. Except when I first try to repressurize the house itself. I can push water throughout the home, but eventually it'll drop (~60 seconds or less).. Here's the kicker, the pump doesn't start at all at this point, it has a mind of it's own & intermittently starts when it wants to. Albeit within a few minutes, pressure builds in 2-3 seconds, immediately back off. Which tells me my new pressure tank isn't taking any water in?

Bad check valve? But why does it only take a few seconds to pressurize the system? Could I have a second dud tank? I get continuous water if I run without the pressure tank connected (which tells me the pump itself is doing its job).. Haven't timed it more than 10 seconds at this point though. But I get full flow immediately once I kick on the breaker.

 

[Reach4]

I presume your pressure switch does not have a lever.

Do you have a control box in line between your pressure switch and your well? If so, that could have a weak start capacitor.

 

[Sponsor]

 

[PNelson1337]

I presume your pressure switch does not have a lever.

Do you have a control box in line between your pressure switch and your well? If so, that could have a weak start capacitor.

Correct, no lever.

Yes, there's a control box.. Installed in 1971 - if the box is to be believed, it's a 1 HP Pump. It's the original cover still, but the capacitor obviously could've been swapped out. I'm already ~1000 into the project, sounds like replacing the control box is the next logical step or just replacing the capacitor.

The whole system was very well maintained I might add, the original plumbing was top notch, as was the electrical work done.

 

[Valveman]

Sounds like you are in the last stages of the normal failure mode for a submersible pump. The only thing that shuts off the water erratically like that is the overload in the motor is tripping. It is an auto-resetting overload. So, the water just seems to magically come back on by itself after a couple minutes. Cycling on and off is the number one cause of this problem. However, the start cap and relay could need replacing, or the voltage could be low. But most likely cycling caused all the problems. Pumps are made to run 24/7/365, it is the cycling on and off that destroys them.

 

[PNelson1337]

Thank you! I'll replace the cap & relay just to rule them out, but it sounds like I'll be pulling the well cap. Guy is supposed to give me a quote on replacing the pump & doing all the leg work, but I'm sure it'll be more than I want to spend.. Particularly if I can do it myself.

So the fact that I can get the pump to run consistently without the system being pressurized still points towards a failing pump? I assume that's because it (the pump) needs to work harder when the system has pressure?

I've read about your CSV..I'll be doing a deep dive into that after this fiasco.

 

[Reach4]

Yes, there's a control box.. Installed in 1971 - if the box is to be believed, it's a 1 HP Pump. It's the original cover still, but the capacitor obviously could've been swapped out. I'm already ~1000 into the project, sounds like replacing the control box is the next logical step or just replacing the capacitor.

Not a lot of people swap out their start capacitors.

https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=start capacitor

However there is another part that can fail on you: the relay. The start capacitor is destined to fail. It is a non-polarized electrolytic. If the start capacitor is the problem, expect the current to be high for several seconds. Then I think some (in your case self resetting) overcurrent/temperature device would trip.

You could measure the current thorough *one* of the hot leads at the pressure switch or before. How long is your water pressure at zero before it starts rising again? 2 seconds? 2 minutes? 200 milliseconds?

The centrifugal pump does not work harder when the system is under pressure-- it is the opposite-- counterintuitive.

 

[PNelson1337]

Not a lot of people swap out their start capacitors.

https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=start capacitor

However there is another part that can fail on you: the relay. The start capacitor is destined to fail. It is a non-polarized electrolytic. If the start capacitor is the problem, expect the current to be high for several seconds. Then I think some (in your case self resetting) overcurrent/temperature device would trip.

You could measure the current thorough *one* of the hot leads at the pressure switch or before. How long is your water pressure at zero before it starts rising again? 2 seconds? 2 minutes? 200 milliseconds?

The centrifugal pump does not work harder when the system is under pressure-- it is the opposite-- counterintuitive.

Replaced the whole control box, issue resolved. System is holding pressure. The next question I have is.. do these work like a forced air furnace, where it should be running for x amount of time? As in, should I limit the flow to control the speed at which the pressure tank is filled. It fills up in 15-20 seconds or less.

I took the well cap off prior to changing the box, there's a threaded connection point to connect a T-Bar/pipe & a rope too. Does that rope run all the way down the well or is it more likely to run to the top of the drop pipe?

Thank you both for the speedy responses though, it's greatly appreciated. It's great to have water again & have a better understanding of the system, plus it's plumbed to more modern standards.

 

[Reach4]

1. Sixty seconds or more is the common target minimum. A CSV can throttle the flow to let you work with a smaller tank, but still minimize cycling. Without a CSV, the nominal tank size should be at least 4X times what the pump puts out in GPM. That is because a pressure tank holds about 1/4 water, and keeps about 3/4 air.

2. Rope may run all of the way to the pump, and would be called a safety rope. Those can be disadvantageous, in that if the rope breaks and falls, it could jam the pump up. The drop pipe should be plenty capable of holding up the pump and wiring, and there is less to go wrong that way. If the rope is steel, it is possible it runs only to the pitless adapter, and is a control for a leg. https://www.bakerwatersystems.com/bulldog-snappy-pitless-adapters/

 

[PNelson1337]

1. Sixty seconds or more is the common target minimum. A CSV can throttle the flow to let you work with a smaller tank, but still minimize cycling. Without a CSV, the nominal tank size should be at least 4X times what the pump puts out in GPM. That is because a pressure tank holds about 1/4 water, and keeps about 3/4 air.

2. Rope may run all of the way to the pump, and would be called a safety rope. Those can be disadvantageous, in that if the rope breaks and falls, it could jam the pump up. The drop pipe should be plenty capable of holding up the pump and wiring, and there is less to go wrong that way. If the rope is steel, it is possible it runs only to the pitless adapter, and is a control for a leg. https://www.bakerwatersystems.com/bulldog-snappy-pitless-adapters/

Sounds like the CSV isn't going to help with my quick fill problem, but will lessen the overall strain on the pump during high usage situations. How do I go about calculating my GPM if I don't know my pump?

It's a standard yellow rope, it's knotted at the top.. Probably been in place a long long time. If I do ever pull the pump, I'll make sure to NOT put a safety rope in place. There's a copper linen(white heat shrink), not connected to anything too.

 

[Reach4]

Let's say the pressure switch is set to 40/60, and the CSV is set to 50. From 40 to 50, the pressure tank fills as fast as the pump can provide water. Above 50, the CSV only passes ~1 gpm. So if you have a 20 gallon tank that holds 5 gallons, when half full, the pressure tank has space for 2.5 gallons. If you stop using water at that point, the pump would run another 2.5 minutes to hit 60 psi, and hit the 60 psi to shut off the pump. If using more than 1 gpm, the pump will continue to run, and the water pressure will be 50 psi.

 

[PNelson1337]

Let's say the pressure switch is set to 40/60, and the CSV is set to 50. From 40 to 50, the pressure tank fills as fast as the pump can provide water. Above 50, the CSV only passes ~1 gpm. So if you have a 20 gallon tank that holds 5 gallons, when half full, the pressure tank has space for 2.5 gallons. If you stop using water at that point, the pump would run another 2.5 minutes to hit 60 psi, and hit the 60 psi to shut off the pump. If using more than 1 gpm, the pump will continue to run, and the water pressure will be 50 psi.

Makes perfect sense now - as it doesn't have any "say" in the pumps start / stop cycles the only way it can possibly do what it does is via controlling the total water entering the system! Appreciate your patience, been a big learning curve the last couple of days!

I currently have a Gould V100 (~32 gallon) tank, at 40/60 the draw down is ~8.6 gallons, if I'm remembering the specs right.

What's the downside of the CSV, I assume there's some type of back pressure put on the pump due to the flow restriction? My apologies for the lack of technical understanding of the systems at this point, I've crammed a lot of knowledge into my little brain in a short period & getting to understand these systems better has been a blast!

 

[Bannerman]

What's the downside of the CSV, I assume there's some type of back pressure put on the pump due to the flow restriction?

Correct, but the higher pressure is a positive (upside), not a downside.

The flow restriction through the CSV will result in higher pressure between the pump and the CSV, but that will reduce the workload on the pump, thereby resulting in it consuming less power and therefore, it will run cooler.

The CSV will prevent the pump from cycling as the pump will only be delivering the specific amount of water that is being used at the time. The pump will continue to operate non-stop for as long as water is being used, but once no further water is needed, the CSV will continue to allow the minimum 1 GPM to pass through, which will continue to fill the pressure tank until the pressure switch shuts off the pump once the cut-out pressure (60 psi) has been achieved.

IF your existing 32 gallon pressure tank continues to operate OK, you may continue to use it, but if your PT needs to be replaced, often a 4.5 gallon PT may replace a larger tank because of the way the CSV functions.

 

[PNelson1337]

Correct, but the higher pressure is a positive (upside), not a downside.

The flow restriction through the CSV will result in higher pressure between the pump and the CSV, but that will reduce the workload on the pump, thereby resulting in it consuming less power and therefore, it will run cooler.

The CSV will prevent the pump from cycling as the pump will only be delivering the specific amount of water that is being used at the time. The pump will continue to operate non-stop for as long as water is being used, but once no further water is needed, the CSV will continue to allow the minimum 1 GPM to pass through, which will continue to fill the pressure tank until the pressure switch shuts off the pump once the cut-out pressure (60 psi) has been achieved.

IF your existing 32 gallon pressure tank continues to operate OK, you may continue to use it, but if your PT needs to be replaced, often a 4.5 gallon PT may replace a larger tank because of the way the CSV functions.

Thank you! Unfortunately, I replaced the pressure tank as part of this little fiasco & learning experience. Would running the tanks in tandem* (since the old one is the same exact model) be of any benefit? Larger drawdown amount so less cycles on the pump? I'm going to order a CSV, thank you for the information!

 

[Reach4]

Running the two tanks would be beneficial if not using a CSV. You would want a good-diameter short distance between the two tanks so they would better act as one.

 

[Bannerman]

Because the pump will not become activated until the system pressure is reduced to the pressure switch cut-in pressure (ie: 40 psi), the pressure to faucets will continue to decline from 60 down to 40. Once the pump is activated, pressure will rise to a constant 50 psi for the remaining time that water is used.

A larger pressure tank will mean the system pressure will be declining for longer time before the pump is activated. To benefit from constant pressure in the shortest amount of time possible, most users prefer to utilize the smallest pressure tank possible. A small tank also costs less to obtain, and requires much less space ongoing.

 

[PNelson1337]

Makes sense, thank you both!

I'll need to think this one through, I hate to add a second point of failure to the system.. the CSV seems to be the best of both worlds in my situation. I hate to waste more money, but going to a smaller tank & reducing strain on the pump seems like a no brainer. I know I COULD use my existing tank, but it seems counter intuitive.. The goal is consistent pressure ASAP basically.


I've got the space - to say my basement is huge would be putting it lightly!

 

[Valveman]

The 32 gallon tank only holds 8 gallons of water. It will be fine with the CSV. It is not like a huge 80 gallon size tank where you would be waiting several minutes to see the strong constant pressure from the CSV. The 8 gallons will be gone quickly and the CSV will give you the pressure you want. With a 40/60 switch, just set the CSV1A for 55 PSI so it doesn't take too long to fill the tank after all the taps are closed. You already have a good tank and pressure switch, so you don't need the complete PK1A kit. You have everything you need except the CSV1A valve. The CSV is not another point for possible failure, but rather the simple long lasting device that will make everything else in the system last much longer.

CSV1A CYCLE STOP VALVE

Compare to the Competition Model CSV1A CYCLE STOP VALVE is recommended for 1 to 25 gpm and is adjustable from 15 psi to 150 psi. It is a stainless steel valve with a molded thermoplastic spring cage. It also has three additional ports (2 - 1/2" and 1- 3/4") and can be used as a pressure tank...

cyclestopvalves.com

 

[PNelson1337]

The 32 gallon tank only holds 8 gallons of water. It will be fine with the CSV. It is not like a huge 80 gallon size tank where you would be waiting several minutes to see the strong constant pressure from the CSV. The 8 gallons will be gone quickly and the CSV will give you the pressure you want. With a 40/60 switch, just set the CSV1A for 55 PSI so it doesn't take too long to fill the tank after all the taps are closed. You already have a good tank and pressure switch, so you don't need the complete PK1A kit. You have everything you need except the CSV1A valve. The CSV is not another point for possible failure, but rather the simple long lasting device that will make everything else in the system last much longer.

CSV1A CYCLE STOP VALVE

Compare to the Competition Model CSV1A CYCLE STOP VALVE is recommended for 1 to 25 gpm and is adjustable from 15 psi to 150 psi. It is a stainless steel valve with a molded thermoplastic spring cage. It also has three additional ports (2 - 1/2" and 1- 3/4") and can be used as a pressure tank...

cyclestopvalves.com

Thanks Cary!

I should've clarified, didn't mean the CSV! I was talking about if I plumbed in a second pressure tank.

I'll grab a CSV & call it a day.

Thank you all for the information & assistance!

 

[Reach4]

I have no experience with it, but potassium permanganate is another thing you could research or test. https://www.mrwa.com/wp-content/uploads/2021/04/14-Iron-and-Manganese.pdf

However https://www.watchwater.com/pdf/katalox-light/Katalox_Light_Comparison_table.pdf seems to say that it is not needed with KL.

Also note that if you change media, the new media probably would need a higher backwash rate.