Very slow drop in pressure at pressure tank

[HollyAR75]

I have a 210' low yield well that fills an underground cistern, which is then piped to my jet pump and pressure tank in my crawlspace. I began noticing that when no water was being used, the pump was cycling every 2-3 hours (I can hear it). First thing I noticed is that when the pump starts up to fill the pressure tank, it shuts off at 41 psi, is this very low? I'm not sure of what psi the pump kicks on. After 90 minutes, it had dropped to 34 psi with no water being used.

No leaks inside the house, toilet are not leaking or running. Foot valve in cistern is less than a year old.

Does this sound like a bad check valve or possibly something wrong with the pressure tank? I've put a call into the well company that setup this system but they can be slow to come out.

 

[Reach4]

Turn off the valve that sends water to the house. If the pressure dropping continues, the problem is somewhere between there and the foot valve. It could be a pipe. It could be a foot valve.

I have a 210' low yield well that fills an underground cistern, which is then piped to my jet pump and pressure tank in my crawlspace. I began noticing that when no water was being used, the pump was cycling every 2-3 hours (I can hear it).

You have two pumps, but I presume you mean the one pumping water from the cistern is cycling; that is the the one that would be associated with the pressure tank.

The pressure tank could have a problem. But that is not going to be the only problem. That could make a small leak have a bigger impact. You should adjust the air precharge to see how much that helps.

First thing I noticed is that when the pump starts up to fill the pressure tank, it shuts off at 41 psi, is this very low? I'm not sure of what psi the pump kicks on.

You might post a photo that shows the jet pump, the pressure switch, the pressure gauge, and the input to the pressure tank.
Pressures are adjustable. It could be normal, but unusual to have a system set up like that on purpose. 30/5o (on at 3o and off at 50 psi) is pretty common. So is 40/60. And the pressure switches are adjustable.

 

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[LLigetfa]

it shuts off at 41 psi, is this very low?

Yes, that is low but I would not trust the gauge to be accurate. Get a new gauge with a garden hose thread so you can attach it to the drain valve at the tank. Then if the two disagree, replace the old one. Probably your pressure switch is factory set to 30/50 which you can confirm when you get a new gauge. If that range of pressure meets your needs, then just confirm that air precharge is around 25 PSI when the water has been drained and the drain valve is open. I prefer 40/60 in which case the precharge should be 35 PSI.

Once you have confirmed proper precharge, run a drawdown test. With no water use, after the pump turns off, drain water into a measuring pail until the pump turns on. The number of gallons measured will be your drawdown. Compare that number with published drawdown tables for your size of tank. If your tank holds air and the drawdown matches what is should be, your tank is fine.

 

[HollyAR75]

Yes, that is low but I would not trust the gauge to be accurate. Get a new gauge with a garden hose thread so you can attach it to the drain valve at the tank. Then if the two disagree, replace the old one. Probably your pressure switch is factory set to 30/50 which you can confirm when you get a new gauge. If that range of pressure meets your needs, then just confirm that air precharge is around 25 PSI when the water has been drained and the drain valve is open. I prefer 40/60 in which case the precharge should be 35 PSI.

Once you have confirmed proper precharge, run a drawdown test. With no water use, after the pump turns off, drain water into a measuring pail until the pump turns on. The number of gallons measured will be your drawdown. Compare that number with published drawdown tables for your size of tank. If your tank holds air and the drawdown matches what is should be, your tank is fine.

It’s a 20 gallon pressure tank, and according to online info I should get about 6 gallons. I would estimate I get 2 to 2 1/2. And to add, the gauge is fairly new.

 

[LLigetfa]

And to add, the gauge is fairly new.

If you read the air pressure while the pump is running, it should be the same as the water pressure. If the two don't match, one of them is wrong.
The cut-out on pressure switches don't usually drift from the factory setting so unless someone was fiddling with it, I would suspect the gauge more than the switch. A new gauge can be damaged by freezing.

 

[HollyAR75]

Talked on the phone with my well service man who will come out on Wednesday. He said I should be getting much more than 2 gallons per cycle. He also asked me to turn the valve off to the house, and watch the pressure. I did that and the pressure has held at 40 so looks like there is a leak on the house side. I don't see any water in the crawlspace and the toilets seems fine, so not sure where to look.

 

[Valveman]

Talked on the phone with my well service man who will come out on Wednesday. He said I should be getting much more than 2 gallons per cycle. He also asked me to turn the valve off to the house, and watch the pressure. I did that and the pressure has held at 40 so looks like there is a leak on the house side. I don't see any water in the crawlspace and the toilets seems fine, so not sure where to look.

Look for a puddle, listen for a leak. And if the diaphragm in your tank is bad study the damage cycling on and off causes to pump systems. A Cycle Stop Valve would give you stronger constant pressure, work with a smaller tank, and keep cycling from destroying the tank bladder, check valve, pressure switch, and most especially the pump/motor. And that is exactly why it maybe hard to talk your well service man into installing one.

 

[Reach4]

Talked on the phone with my well service man who will come out on Wednesday. He said I should be getting much more than 2 gallons per cycle. He also asked me to turn the valve off to the house, and watch the pressure. I did that and the pressure has held at 40 so looks like there is a leak on the house side. I don't see any water in the crawlspace and the toilets seems fine, so not sure where to look.

These are some things that could have gone unnoticed:
Look at output of drain on water softener; should be no flow except during regen. RO unit. Humidifier. Icemaker.

Turn off the stop valve for each toilet at the wall.

Turn off the supply valve to the WH. That is not an absolute guarantee that it is not a hot water pipe leaking (possible crossover), but if that stops the cycling, it guarantees there is a hot water leak.

 

[HollyAR75]

Thank you for all the help and suggestions. I did test the toilet tanks with blue dye and it didn't bleed into the bowl. I also think I made a mistake with the size of my pressure tank. It's a Fiberwound Signature 2000 series, model S35-10-01. What size is this? I'm thinking 35 gallon which is even worse of a problem since I get about 2.25 gallon drawdown.

I've looked repeatedly under the house in the crawlspace and I don't see any water spots of hear anything. Well service man said he will be here Wednesday.

Btw: the water is being pulled from a cistern, not the well pump itself.

Also to add, sorry I'm doing the best I can. I'm by myself at the house attempting to deal with this. I do understand how my water system works to a certain point.

 

[Reach4]

Thank you for all the help and suggestions. I did test the toilet tanks with blue dye and it didn't bleed into the bowl. I also think I made a mistake with the size of my pressure tank. It's a Fiberwound Signature 2000 series, model S35-10-01. What size is this?

http://www.gulfsouthsupply.net/files/Pages_160-162.pdf

You are getting a new pressure tank with a diaphragm instead of a bladder. That one you have has a replaceable air cell, but I don't think those are economically replaceable.

Normally it is recommended to check and restore the air precharge annually. I go longer than that, but you have probably gone a lot longer. When I mentioned "precharge" before, you could have searched for how to set that. You could have posted back asking about that.