Pressure Tank Pressure Dropping When Water to House Shut Off

[Calhoontuna]

Of late, I've been noting that our pressure tank has been kicking in when no water is being used or has been used for quite a while.

We have well water with a pressure tank set at 30-50.

This morning I had closed the main valve between the pressure tank and the rest of the house and noted that over the course of 4 hours the pressure dropped from 50 psi to 40 psi.

Is this indicative of a bad pressure tank?

I had thought that on one cycle that I happened to have been watching the needle dropped down to 20 psi before cutting in. However, I watched the next cycle and it worked the way it was supposed to, kicking in at 30 psi, so I was unsure if I had read it wrong.

 

[Reach4]

Indicative of a small leak. A pressure tank problem could make that slow leak cycle faster than a good pressure tank.

Leak could be pretty much anywhere between the pressure tank and the pump.

For pressure tank, there are checks you can do. Turn off the pump, and drain the water pressure to zero. Check air precharge. If this a submersible (down the well) pump, 28 PSI is good. If this is a jet pump, air precharge might be 25 to avoid a stutter in water pressure as the pump starts. With water pressure at zero, there should not be water in the tank. So the tank will be light.

With the pressure up to 50, turn off the pump. See how much water will flow into a series of buckets. Normal is about 25% of the nominal tank size. For example, with 32 gallon tank, expect about 8 gallons of water before the pressure drops below 28.

 

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[Valveman]

Most likely the check valve on the pump is leaking back. Make sure the ball valve to the house is good and not leaking past. Then you know the water is going back down the well. Adding a check valve before the tank will solve this problem but causes several others. The check valve on the pump will need to be replaced to solve the problem. Oh and BTW, check valves, tank bladders, and everything else in a pump system fails because the pump was cycling on and off too much.

 

[Calhoontuna]

Most likely the check valve on the pump is leaking back. Make sure the ball valve to the house is good and not leaking past. Then you know the water is going back down the well. Adding a check valve before the tank will solve this problem but causes several others. The check valve on the pump will need to be replaced to solve the problem. Oh and BTW, check valves, tank bladders, and everything else in a pump system fails because the pump was cycling on and off too much.

I didn't know what a check value was until today.

Looking downstairs by my pressure tank I see what I'm taking to be a check valve on the pipe between the tank and the switch and gauage.

If this were a check valve are you saying there would be another valve down in the well and if I were to replace this check valve in my basement it's not really fixing the prob.

 

[Calhoontuna]

I didn't know what a check value was until today.

Looking downstairs by my pressure tank I see what I'm taking to be a check valve on the pipe between the tank and the switch and gauage.

If this were a check valve are you saying there would be another valve down in the well and if I were to replace this check valve in my basement it's not really fixing the prob.Afte

 

[Calhoontuna]

Think I've finally got it figured out.

Valveman -- you were correct the shut off valve was not shutting completely. You really had to crank on it to close it fully.

At which point, i didn't loose any psi at all.

So during those previous tests water had been getting past shut off and leaking somewhere.

After running around the house turning off toilets and sinks I narrowed it down to the water softener.

When I turn the lever to bypass the water softer, there is no drop in pressure, but when the water softener is in use I do loose pressure, even though it's in service and not rejuvenating.

I had assumed that the water softener only used water when it ran through its cycles but it appears that when it's just sitting there in "in service" mode it's slowly using water. Is this normal?

 

[WorthFlorida]

At the water softener, check the discharge drain line, during idle no water should be flowing. Note the water level inside the brine tank and see if the water level rises after the regen cycle is complete.

Do you by chance have a RO filter (usually under the sink)?

 

[Calhoontuna]

No RO filter. Water wasn't' flowing through the discharge drain line during idle that I noticed...though I will have to monitor it to make sure. As for the brine tank I never paid attention to the water level so i will have to watch that.

 

[Reach4]

I expect your softener is putting out water to the drain while in service. You would have noticed another kind of leaking from the brine tank.

A rebuild kit, or at least new seals and piston would be the ticket for many softeners. Use silicone release compound very lightly on the seals and piston. The rebuild kit may come with the appropriate lube.

It is important to get the right piston, because there are different types.

If this is a cabinet type softener, things are different.

 

[Calhoontuna]

I expect your softener is putting out water to the drain while in service. You would have noticed another kind of leaking from the brine tank.

A rebuild kit, or at least new seals and piston would be the ticket for many softeners. Use silicone release compound very lightly on the seals and piston. The rebuild kit may come with the appropriate lube.

It is important to get the right piston, because there are different types.

If this is a cabinet type softener, things are different.

This is driving me absolutely crazy,

Was almost positive the softner was the culprit, but that is not the case. Wasn't leaking into the utility tub, and now I'm getting instances where the pressure tank psi drops when the softener is in bypass mode/not plugged in.

However, contrary to my original post it does seem that when I crank the shut-off to the house FULLY shut, the psi is rock solid. I've done this I don't know how many times now over the course of several hours and the thing does not move, but will continue testing.

When you do this, does this conclusively rule out the pressure tank and the well. My understanding was that is the case and it stands to reason, but I can't figure out where the water is going. I've been systematically going through and turning off fixtures and last night looked behind the walls in the shower to make sure there was no dripping there.

One question I had was what about the water heater? Was looking in the book and online and wasn't getting an answer. Wasn't sure when a regular tank-style water heater refills (Brandford White -Defender Safety System in my case) and was thinking maybe that was the culprit, maybe it refills gradually or intermittently and was sucking off the pressure tank.

 

[Reach4]

This conclusively rules out the pressure tank and the well as the source of the leak or sag in pressure.

If your pressure tank is in good shape, and we assume a 32 gallon pressure tank, that will hold about 8 gallons of water. So without going thru the Boyles law calculations, I am thinking that might be a loss of roughly 3.5 gallons in 4 hours.

Water heater system can lose water by leaking/sending water out of the T&P drain. Check that pipe output. In Wisconsin I would expect that pipe to exit indoors and visible, but people have been known to improperly route that to the crawl space, where it goes unnoticed.

In any case, you could close the cold supply valve to the WH. Then repeat your test.

Another prime place for losing water (and maybe more likely) is in a toilet. You could close the valve at the wall. Then flush the toilet. After the 4-hour test, the water in the tank should not have risen. This proposed test checks the toilet a a source of loss, and if pressure tank loss occurs, checks that the stop valve at the wall did isolate the toilet as intended.

 

[Calhoontuna]

This conclusively rules out the pressure tank and the well as the source of the leak or sag in pressure.

If your pressure tank is in good shape, and we assume a 32 gallon pressure tank, that will hold about 8 gallons of water. So without going thru the Boyles law calculations, I am thinking that might be a loss of roughly 3.5 gallons in 4 hours.

Water heater system can lose water by leaking/sending water out of the T&P drain. Check that pipe output. In Wisconsin I would expect that pipe to exit indoors and visible, but people have been known to improperly route that to the crawl space, where it goes unnoticed.

In any case, you could close the cold supply valve to the WH. Then repeat your test.

Another prime place for losing water (and maybe more likely) is in a toilet. You could close the valve at the wall. Then flush the toilet. After the 4-hour test, the water in the tank should not have risen. This proposed test checks the toilet a a source of loss, and if pressure tank loss occurs, checks that the stop valve at the wall did isolate the toilet as intended.

Thanks Reach!

I'll run some experiments on the T&P and toilets over the next few days and see if I can track it down.

 

[Calhoontuna]

Reach -- one quick question though. So when does the water heater fill? There was a lot of information online about how water heaters work but I wasn't seeing anything on what triggers the thing to refill.

 

[Reach4]

1. Use of hot water causes refill. Water exiting the T&P drain causes water to fill to make up the difference.

2. Hot water cooling shrinks the hot water... However most people with wells and pressure tanks don't have check valves between the pressure tank and the WH. For them, a WH turning on and off will not cause a net loss of water. There are exceptions where a check valve is installed after the pressure tank. The two reasons I know of is some water treatment gadgets need that, and a check valve after the softener will prevent phantom flow. Again, this is unlikely to apply to the average well owner.

 

[Calhoontuna]

1. Use of hot water causes refill. Water exiting the T&P drain causes water to fill to make up the difference.

2. Hot water cooling shrinks the hot water... However most people with wells and pressure tanks don't have check valves between the pressure tank and the WH. For them, a WH turning on and off will not cause a net loss of water. There are exceptions where a check valve is installed after the pressure tank. The two reasons I know of is some water treatment gadgets need that, and a check valve after the softener will prevent phantom flow. Again, this is unlikely to apply to the average well owner.

Thanks Reach4! I will continue testing.