Well seal jumping when pump stops

[DrVlikhell]

This is my first time posting here but I've been reading this forum for years when I've needed plumbing help and this place has been a great resource, so first I'd like to say thanks a ton for that.

Now it seems I may have a unique problem. The seal and pipe on my well jumps every time the pump shuts off. It actually lifts right off the pvc casing when the pressure switch cuts power to the pump. At first I only noticed a leak in one of the fittings near the well head, so I spent the next embarrassing number of hours fixing that. Once it was finally done I powered the system back up and saw the well seal and pipe jump. It does it every time and I don't know how long it's been doing it. I'm guessing the jumping is what caused the crack in the fitting that I replaced.

The well seal is one piece plastic with rusted bolts. The well casing is all pvc because I'm in South Florida with zero frost line. I'll attach some pictures but it looks pretty standard, I think. Is there anything I can do to get the well seal to stay seated, or is the only option to replace the seal? If I have to replace it, I'm guessing I have to lift the pump and pipe and suspend it, cut the top of the pipe off to get the old seal off and the new one on, then reattach the pipe, lower it back onto the casing and secure the new seal. I'm also guessing I'm missing half a dozen steps or more... like how the water pipe secures/attaches to the seal.

I do all my home repairs myself (plumbing, electrical, framing, three mini splits, etc) but I'm feeling a bit intimidated with this one to be honest. Mostly because I don't want to do something stupid like break the pipe and drop the pump down into the well. Also because I don't know how everything is attached inside the casing. There is also a second pvc casing around the first one. I don't know what that's about, you can barely see it in the pictures.

The pictures show the well casing and seal. First in line on the pipe is a brass valve that I don't think needs to be there? Then the pressure switch, gauge, 90, and a spigot. Pictures were taken before I replaced the leaking threaded fitting. I have the breaker for the pump switched off for now so it doesn't break anything else. If you guys can point me in the right direction I'd really appreciate it.

 

[Valveman]

Replacing the seal in not the answer. Stopping the water hammer is the answer. The pressure tank maybe waterlogged, and there is no air cushion. You could have an extra check valve in the line, but I don't see it. Extra check valves usually cause water hammer on pump start, not stop though. The check valve on the pump could be sticking. Check valves get worn out from the pump cycling on and off and slamming shut with each stop.

If the tank is bad or not, adding a Cycle Stop Valve gives a mechanical soft stop and eliminates water hammer on pump stop. The CSV fills the tank at 1 GPM so the check valve is barely open when the pump shuts off.

 

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[DrVlikhell]

Replacing the seal in not the answer. Stopping the water hammer is the answer. The pressure tank maybe waterlogged, and there is no air cushion. You could have an extra check valve in the line, but I don't see it. Extra check valves usually cause water hammer on pump start, not stop though. The check valve on the pump could be sticking. Check valves get worn out from the pump cycling on and off and slamming shut with each stop.

If the tank is bad or not, adding a Cycle Stop Valve gives a mechanical soft stop and eliminates water hammer on pump stop. The CSV fills the tank at 1 GPM so the check valve is barely open when the pump shuts off.

I've never experienced water hammer before but if that is the problem, and not the well seal, that's a much easier problem to fix. I can definitely deal with that.

The pressure tank may be bad. It was acting funny and gurgling/chugging to let air in and water out when I had the pipes open, sort of like if you hold a gallon jug or two liter soda bottle upside down for it to empty. I figured that if the bladder inside the tank was working properly it would just let the water out of the bladder and that would be the end of it, but it kept going and chugging for probably 20 minutes. This was well after the first section of pipe had been cut so there was zero pressure.

The CSV looks like a great idea, however this pump and pressure tank only fill an aerator tank so there's no change in flow rate demands while the pump is running, and the well pump does not cycle on and off while the aerator tank is being filled. I do feel that the well pump turns on too frequently to top off the aerator tank, but I think that has more to do with the float switch inside the tank being on too short of a lead.

It looks like I will get to investigating/replacing the pressure tank. Once that's cleared up I'll see about potentially installing a CSV for the pump inside the aerator that feeds the house. Thank you very much for the input and advice!

 

[DrVlikhell]

I drained the pressure tank and there doesn't seem to be any water left inside after the pressure is gone, so I guess it's not leaking unless the bladder is completely torn. It seems to take about 10 seconds to go from 30 to 60 psi, and around a minute to go from zero to 60. There is a leak from the pipe on the bottom so I have to remove it to fix that. I guess I'll get a better idea once I do that and can shake it around to see if there's water on top of the bladder

 

[Valveman]

I drained the pressure tank and there doesn't seem to be any water left inside after the pressure is gone, so I guess it's not leaking unless the bladder is completely torn. It seems to take about 10 seconds to go from 30 to 60 psi, and around a minute to go from zero to 60. There is a leak from the pipe on the bottom so I have to remove it to fix that. I guess I'll get a better idea once I do that and can shake it around to see if there's water on top of the bladder

How much air pressure was in the tank after the water side was drained down to zero?

 

[Valveman]

I drained the pressure tank and there doesn't seem to be any water left inside after the pressure is gone, so I guess it's not leaking unless the bladder is completely torn. It seems to take about 10 seconds to go from 30 to 60 psi, and around a minute to go from zero to 60. There is a leak from the pipe on the bottom so I have to remove it to fix that. I guess I'll get a better idea once I do that and can shake it around to see if there's water on top of the bladder

How large is the pressure tank now? If the bladder is torn as I suspect, it has been cycling more than you think. Yes, moving the float switch lower in the aerator tank will give loner and fewer cycles on the well pump. Could be it fills the aerator tank so quickly now the pump isn't cycling because it barely used the water from the pressure tank before the aerator tank is full. Lowering the float in the aerator may make the well pump cycle on and off.

If you need to replace the tank a 4.5 gallon size like in the PK1A kit is all you need. You may not need the CSV to eliminate cycling if the aerator tank is filling as fast as the well pump is supplying. But that may change is you lower the float switch. The CSV would also let you use a very small 4.5 gallon size tank, and would eliminate water hammer from from stop, which causes check valve failure and is the reason for the title of this thread.

 

[DrVlikhell]

How much air pressure was in the tank after the water side was drained down to zero?

Finally had a chance to work on it again. It seems I'm able to instantly conjure thunderstorms by simply picking up a pipe wrench.

The pressure tank is 20 gallons and had 35psi when the water was at 60psi. I drained the system and the pressure tank went down to zero psi. I cut the tank off and aired it up with my compressor. It was very light when I carried it over to my compressor. Maybe a cup or two of water and a bit of air came out of it at first but then it aired up and held pressure. I put it at 30psi and it held that for the next four hours. I lowered the pressure in the tank down to 28 because something in my head said that's the correct pressure. Then I replaced the leaking coupler on the bottom of the pressure tank and reinstalled it. I also added a Zurn 1260XL water hammer arrestor hoping that would help solve the problem.

At first I thought it didn't work because after I plugged in the pump to pressurize the pipes and look for leaks, the well seal jumped off the casing as before when the pump shut off. But then I triggered the aerator tank to refill itself in order to get any remaining air out of the pipes. The pump did not cycle at all while filling the aerator tank. The pressure raised to about 47 or 48psi and stayed there for several minutes while the aerator tank filled. This time, once the tank was filled and the pump shut off it did not jump. I opened the spigot to bleed off pressure so the pump would run again, and when the pump stopped, again it didn't jump. So either the pressure tank was low on air, or the water hammer arrestor is working. I think I hear a click noise that comes from the arrestor as the pump shuts off, so maybe that's it working. The pressure tank now reads 37psi when the water is at 60psi.

If the check valve on the in ground pump is sticking and causing the water hammer... well, I'll wait until it fails entirely before I pull it up to replace it. That'll give me time to prepare for a job like that.

I will continue to monitor the well system to see if it changes behavior.

I think there is a problem on the house supply side of the system though. The pump in the aerator that supplies the house seems to cycle faster than it should. A toilet flush makes it cycle at least twice. Having a garden hose running causes it to cycle every 30 seconds or so. I will check the pressure tank on that pump tomorrow. It's much newer than the other one so I wasn't anticipating any issues with it. Unfortunately there does not seem to be a pressure gauge on that side unless it's hidden somewhere under the decorative purple leafed plants.

Anyways, thanks for reading my book of todays adventures and much more importantly, thank you for pointing me in the right direction.

 

[Reach4]

The pressure tank is 20 gallons and had 35psi when the water was at 60psi. I drained the system and the pressure tank went down to zero psi. I cut the tank off and aired it up with my compressor. It was very light when I carried it over to my compressor. Maybe a cup or two of water and a bit of air came out of it at first but then it aired up and held pressure. I put it at 30psi and it held that for the next four hours. I lowered the pressure in the tank down to 28 because something in my head said that's the correct pressure. Then I replaced the leaking coupler on the bottom of the pressure tank and reinstalled it. I also added a Zurn 1260XL water hammer arrestor hoping that would help solve the problem.

That does not make sense to have water pressure at 60 and the air pressure 30, if the water pressure gauge is piped to input to the pressure tank. If the water pressure gets significantly higher than the air pressure, the diaphragm would move up. The air pressure would rise because the air space gets smaller, so the water pressure and air pressure would nearly equalize. The diaphragm should act limp during normal conditions.

At intermediate pressures, expect the water pressure and air pressure to be within about 1 psi of equal. This can be used to compare the calibration on the air pressure gauge and the water pressure gauge.

There is a dome on some pressure tanks (that does not block air) above the diaphragm to prevent the diaphragm from over-stretching if the air pressure is way low. The diaphragm does not normally get that high before the pressure switch cuts off the pump.

So I am thinking that one of your gauges is significantly off, or the air pressure was not 35psi simultaneously to when the water pressure was at 60psi.

I am glad things are working much better for you.

 

[DrVlikhell]

That does not make sense to have water pressure at 60 and the air pressure 30, if the water pressure gauge is piped to input to the pressure tank. If the water pressure gets significantly higher than the air pressure, the diaphragm would move up. The air pressure would rise because the air space gets smaller, so the water pressure and air pressure would nearly equalize. The diaphragm should act limp during normal conditions.

At intermediate pressures, expect the water pressure and air pressure to be within about 1 psi of equal. This can be used to compare the calibration on the air pressure gauge and the water pressure gauge.

There is a dome on some pressure tanks (that does not block air) above the diaphragm to prevent the diaphragm from over-stretching if the air pressure is way low. The diaphragm does not normally get that high before the pressure switch cuts off the pump.

So I am thinking that one of your gauges is significantly off, or the air pressure was not 35psi simultaneously to when the water pressure was at 60psi.

I am glad things are working much better for you.

I don't know what to tell you about the pressures. The pressure tank is sitting right next to the well head where the water pressure gauge is, so they're always checked simultaneously. I'm literally reaching over one to get to the other. I'm certain the gauge on the pipe is at least close to accurate because it reflects what the pressure switch is set to, which I believe is 60psi for the high side and either 30 or 40 for the low side, I can't remember which. The gauge is installed directly next to the pressure switch. I actually used two different gauges to check air pressure on the tank, one Campbell Hausfeld tire inflator that I used to inflate it with, and then a Bontrager "Turbo Charger" floor pump, which is definitely known to be accurate.

Should I have put more air into the pressure tank? Can a pressure tank get worn out from age, but not leak? Or should I just not worry about it since that part of the system seems to be working fine now? Regardless, I'm going to keep an eye on it.

 

[Reach4]

I don't think a tank can get worn out and not appear to leak, plus be light when the water pressure is zero. Some slow leaks can get a lot of water above the diaphragm, but they will not be light.

I don't know how to resolve what appears to be an inconstancy.

I would re-check the pressures with the pump not running, and the water pressure roughly midway in pressure.

 

[Valveman]

The pressure tank IS the water hammer arrestor. It just has to have a good diaphragm and the correct air charge to work properly. When the pump is on the air side of the tank should read the same pressure as the water pressure gauge. Your reading make me think the inlet to the tank is blocked. But something is wrong with the tank from everything you have said.

 

[LLigetfa]

The pressure tank IS the water hammer arrestor. It just has to have a good diaphragm and the correct air charge to work properly.

Be aware that some tanks have an internal dome limiter where if there is not enough air precharge, the diaphragm will hit up against this limiter with a resulting sudden pressure spike.