Internal bladder type water pressure tank diagnostic questions & answers:

These questions & answers help diagnos & fix problems traced to the internal bladder used in water pressure tanks.

This article series describes the diagnosis and repair of internal bladder type water pressure tanks: how they work, what goes wrong, how to fix it.

Water Pressure Tank Diagnostic Questions & Answers, Series 2

These questions and answers about diagnosing problems in water pressure tanks were posted originally

at WATER TANK BLADDER PRESSURE ADJUSTMENT - topic home. Be sure to see that article.

Also see WATER TANK BLADDER REPLACEMENT

and WATER PRESSURE LOSS DIAGNOSIS & REPAIR

On 2017-12-08 by (mod) - the water tank seems empty and pressure falls off quickly

Rob,

Running out of water in the well can cause the symptom you describe.

If you leave water off for more than a few minutes and you see that you have more water (before running out) after that, the implication is that the flow rate of your well is poor and it needs a long recovery time.

The short click-on time suggests a water logged pressure tank.

The water pressure tank normally is about 1/2 to 2/3 full of water when the pump shuts off. Your tank pre-charge pressure is correct if you're measuring that under the right conditions: pump turned off, all water pressure drained from the system.

The button on the filter is to release pressure before unscrewing the filter base in order to change the cartridge.

I'd be sure you have pre-charged the tank correctly, then wait several hours or longer to see how the system behaves when you next run water.

Also check that water is actually entering the water tank. If when the pump turns off the water tank still seems empty (light) then the bladder may be stuck over the tank entry.

See WATER TANK BLADDER STUCK to ITSELF

On 2017-12-07 by Rob

I lost power to my pump after I switched the spot of the pump breaker with another breaker in my panel. I switched them back and had water. The next day I lost water pressure, water would come out in a trickle. I have a bladder in my pressure tank.

Since then I have fixed the wiring issue, cleaned and checked the power to the pump, replaced the pressure switch and still very little pressure.

If I do not turn the water on for a few minutes I have about 30 seconds of pressure before it fades. The pressure in the tank is set at 28psi for a 30-50 pressure switch. The tank seems empty. The pressure switch will click on and then click off after a very short time. Nothing seemed to fix the issue.

There is a water softener system in place with a filter after the softener. I noticed there was still water in the line to the filter. The filter is screwed into the line.

There is a handle on top of the filter that gives access to a red button that when I pressed I got air and then water coming out. Now I dont have any water. Can a collapsed bladder still have the 28psi? Could air be blocking water from getting to faucet?

On 2017-08-26 1 by (mod) - old water tank can be left in place?

Yes, Jim, you could leave an old tank, by installing a new pressure tank sufficiently-close to the location of the pressure control switch. But it would make sense to cut-off water from entering the tank since if it is not functional it could become a bacterial or other pathogen reservoir.

On 2017-06-14 by Jim

Can I leave bad bladder tank in and install a new one

On 2017-06-11 by (mod) - can air accumulate in the pressure tank?

Drew:

While a pressure tank might accumulate an air charge if there is air in the water supply system it would not be responsible for its source. More likely there's a leak in the well piping or low water in the well.

Please use the box above to search InspectApedia for AIR DISCHARGE AT FIXTURES to read the more-likely causes of the problem you describe. Take a look at that article and then ask more questions as needed.

On 2017-06-11 by Drew

In the past month, we have had air in our water lines whenever the sprinkler system is running and we are running water in the house (shower, sink, etc).

I think we have a bladder style tank because of the Schrader valve near the top. I checked the pressure tank (the last time this happened and the gauge was down to 30psi (I have never see it this low) and the compressor was not cycling. Also, there was almost no water in the tank (80 gallon and I could move it easily).

I had a plumber come out to check the system and he made a few adjustments, but said everything looked fine. Also, the tank is filling to just under half. In the past it usually held to around 3/4 full. We are still having this problem, even after the plumber checked the system.

On 2017-05-20 by (mod) - how To check "operating water pressure" at a building

When water is being used in building at a very fast flow rate or consumption rate, then it may be normal for the well pump pump to run continuously.

To check "operating water pressure" at a building you can make several measurements by simply connecting a pressure gauge to an outside faucet:

1. Measure the water pressure when the pump turns OFF - this is the maximum pressure your building will see at that point. This is the pressure control switch CUT OFF pressure or CUT OUT pressure.
2. Measure the water pressure after water is run in the building until the pump turns ON. This is the pressure control switch CUT ON or CUT IN pressure.
3. Measure the water pressure when multiple faucets are being run in the building such that the pump is running continuously. This will approximate the maximum sustained water pressure when your building occupants are using water at a high rate. Naturally if still more fixtures are operating the building water pressure will be a bit lower.
4. Measure the water pressures as in cases 1 - 3 again at the highest floor in the building as this will normally be the lowest deliveed water pressure.

On 2017-05-20 by Steve Pozgaj - procedure to check operating water pressure

We have a Wellmate WM0075 unit. I was told this procedure to check operating pressure:

-connect hose & run water

-should drain pressure from 60psi (hi) to 40psi (lo)

-then should take ~25secs to build pressure back from 40psi to 60psi

However, I'm not clear on whether I'm to stop the water flow when it hits 40psi, or to keep the flow open, watching it climb back to 60psi.

With the flow off hitting 40psi, it takes ~22secs to get to 60psi, but with the flow open, it takes between 45-75 secs.

Can you please clarify? Thanks.

On 2017-01-28 byCorey W.
@Corey W., 3/4"

I used all 1" copper for main supply and cold treated supply. 2/3" copper for hot supply.

On 2017-01-28 by Corey W

Does a pressure tank have to be first inline? I've had to do some major re-arranging of my water system while not taking it down for more than a few hours.

Now it's time to move (probably replace) the pressure tank. Does the main water line from the well have to go directly to the tank first? Can i tee off for main supply before the tank? Would it make a difference where the pressure switch goes?

On 2017-01-24 by bob

replaced water pump in well but still no water what may the problem be

On 2016-11-30 by Brent D.

I have a deep-well submersible (815') 2HP motor / 5GPM pump feeding a 86 gallon pressure tank at 30#/50# with a mfr. stated drawdown of 29.2 gallons.

Pump completes pressurization (from 30# to 50#) in 1:30 which well driller said needs to be at least 2 minutes to avoid pump motor damage. Measured drawdown 5 times in a row and it is consistent at 13.5Gal. Pre-Pressure measured 25.5PSI which I increased to 28PSI. This had no impact on pressurization time.

Since my measured drawdown was less than half the mfr. spec. of 29.2gal, I thought the tank might be waterlogged.

Shut off pump breaker and let water drain until gauge read 0#. Tried tapping tank from bottom to top and received a hollow sound, not a thud, which makes me believe it isn't waterlogged. Also tried rocking pressure tank and it felt empty and there was no sound of water sloshing around in tank.

Any ideas why I don't get a better drawdown with no indication of being waterlogged?? Is there another explanation for these symptoms. I don't want to pay around $1000 to purchase, ship, and install a replacement pressure tank unless I am sure this is the problem. Thanks for any assistance you can provide.

Question: does a pump need a bladder tank?

(Jan 23, 2014) Mary said:

Does a pump need a bladder tank to pump to house?

Reply:

In most systems, yes Mary. Without a water pressure tank the pump will cycle on and off rapidly, risking pump damage and delivering surging water. There are some exceptions but what I describe is the case for a typical residential system.

Question: shared well, lost power, but water doesn't make it up to my house

Hello I have a well shared with a neighbor my well is located down at the bottom of my property I lost power lines wrecked by downed trees underground now power provided by neighbor moved pressure tank and pressure switch to well site as needed for power 85 gallon tank replaced 30/50 with 40/60 switch

neighbor gets plenty of water now does not make it up hill get air and that's all will reset tank pressure to 38 any other suggestions has to climb hill 400 ft plus to my house? - Lloyd 4/5/12

Reply:

Moving the tank and switch downhill to the neighbor probably means that the output pressure of that equpment isn't enough to push water uphill to your house.

Lee Dilkie said:

Lloyd,

Probably too late to help, I'm sure your issue is sorted now but it is an interesting question to answer.

You have a big issue with trying to pump water to two separate locations, with one 400' above the other.

Firstly, it takes ~15psi to pump water up 33', so your 400' rise would require ~180psi of pressure at the well head just to get the water to the house at the top, add 20psi so water actually flows and you are taking 200psi at the well head. Which isn't so good for your neighbour down at the well head elevation, 200psi will blow out all his plumbing fixtures unless you install a pressure reducing valve.

Also, the line from the well head to your house will need check valves installed every X feet of rise to ensure the line's max pressure rating isn't exceeded.

If your house is 400' away but not 400' "up", then you can use the above equation to calculate the pressure required at the well head.

Most pressure switches I've used allow you to adjust the "turn-on" setting (turn-off is usually fixed at 20psi below turn-off). Just take off the cover and turn the screw down to increase the spring pressure. Don't know how high they go, never tried.

Another option is to install a separate jet pump to push the water up to your house, then your neighbour won't see the extra pressure (install a check valve below the jet pump).

But I am confused, you didn't say how this "shared" well was configured in the first place? Do you have separate lines into the well? Is your pump submisrable (can't see that) or a two pipe jet pump (doesn't make much sense to me either).

oh, i see, just re-read your post... you moved your pressure tank and switch downhill.

-lee

Question: pump doesn't shut off, now no water pressure

First I noticed water pump was not shutting off, went to check pump it was hot so Shut off pwere to pump, shut off till pump cooled turned back on , no water pressure and pump would not shut off, cleaned points , did not do any good, I get water when turned on not much about 22psi.. should be at about 40psi for my well, please help.. - Ruby Berarducci 4/28/12

Reply:

When a pump runs continuously and there is no water pressure you may have any of several possible causes such has an exhausted well, well piping leak, or damaged pump.

See WATER PRESSURE PROBLEM DIAGNOSIS TABLE

Question:40-60 pressure switch with bladder air tanks.

Can i use a 40-60 pressure switch with bladder air tanks. Your tanks are rated at 50 PSI max. Is this bladder pressure of water pressure. Thank you - Tom Renzo 4/28/12

Reply:

Yes but you have to set the pressure cut-out down to 50 psi. Drop the cut-in to 30 psi and you'll be OK.

Question: how do I get 100 psi of water pressure in my home?

How can get a bladder tank constantly produce 100psi pressure? - Pete 5/5/12

Reply: you don't

Pete, you can't. A home residential water supply system is not intended to operate in that pressure range and would be unsafe.

Question: pump runs continuosly when our sprinkler system is on

I have a WX-250 that comes shipped with 30psi, I have filled it to 38, the switch is a 40/60 should the pump continually run when sprinkler systems are going? - Susan 6/2/12

Reply:

Susan if the water draw rate from your sprinkler in gpm exceeds what the pump and/or well can deliver, the pump may run continuously. Check first that there is no hidden leak in your sprinker system piping.

 

Question: water pressure gauge moves too slowly, I think this is causing my water tank to malfunction

(Sept 23, 2016) Wayne Nelson said:
Everything works fine on my pump. The Guage doesn't drop fast enough to keep my holding tank from almost going empty. I have to manually make the Guage go to 37 psi to activate the water to go to holding tank. Please help.

Reply:

The gauge doesn't do anything but show pressure - it is not a control device. A separate pressure control switch turns the pump on and off; it may be debris clogged and need replacement.

Question: pressure tank for industrial pumps

(Oct 29, 2016) waseem said:
How much air should b in a bladder type tank industrial pumps

Reply:

Waterman

For water delivery systems, with the water pressure tank empty, set the air pre-charged pressure - 2 PSI below the pressure switch cut in pressure setting.

Question: well pump is turning on and off repeatedly

(Oct 31, 2016) Rich said:
Hello, I have a 300ft deep well (residential use) 1hp pump with a 62gal bladder tank which is about 12yrs old. The outside condition looks good, no rust. I also have a 40-60 pressure switch and a 100psi gauge which I just replaced on 10/29/2016.

My question is: While running water my system cycles, builds up to cut off then drops to cut in, .

then runs back up to cut off. Repeating. When water is turned off the tank holds the pressure (no loss). Am I looking at a leak or low pressure in my tank, or some other problem ? Thank you for your assistance. Also I hope I'm in the right spot !!

Reply:

Sounds like a waterlogged pressure tank. Please use the InspectApedia.com search box and search for WELL PUMP SHORT CYCLING to read how to diagnose and cure the problem you describe.

Question: pressure drops below cut-in

(Nov 4, 2016) Carol said:
My cut in pressure is 40 and cut off is 60. When the water is turned on the pressure gauge drops to 30 before going up to 60. It then goes back down to 40. Why does the pressure drop down to 30 initially? Should I adjust it up?

Reply:

check for a clogged pressure sensor on the pressure control switch, or just replace the switch

Question: pressure tank only goes up about 2 psi when the pump runs

(Nov 5, 2016) shawn said:
new diaphragm tank installed yesterday. proper air pressure settings set. dialed pressure switch to 35-55.

worked great for the evening and night. this morning lost water pressure. reset breaker noticed pressure tank would only pressurize a couple of PSI per cycle

Reply:

(Nov 13, 2016) Suzanne Manchester said:

Set the air pressure in the empty water tank to 2 psi below the well pump pressure switch cut-in pressure.

Something's missing and I don't know what the rest of this sentence should be:

Bleed air pressure out of the water tank, or add air pressure into the water tank, until the tank pressure.

For example, if your well pump pressure control switch is set to "cut in" (start pumping water from the well) at 30 psi, then set the pressure tank to (30 - 2) = 28 psi.

Question: valve on pressure tank is leaking air when I take off the cap - is this normal?

2016/11/21 John said:

Just shocked well , after flood. Air presure valve was removed ,reinstalled.valve leeks air without airvalve cap. Is this normal?

Reply: no. tighten or replace the valve stem core.

No, John. We shouldn't see water (nor air) leaking from the air valve.

Stop by your auto parts store, pick up a tire valve replacement tool - you'll need this to un screw the actual valve core from the stem. Try removing, cleaning, and replacing the existing valve core, or just install a new one.

Watch out: on some well systems, particularly those using a submersible pump and an in-well snifter valve, the above-ground snifter valve core spring is a softer one than is used in car tires since it needs to open and close at a lower pressure range. If the auto type replacement core gives trouble later (such as inadequate control of the air volume in a pressure tank that does not use an internal bladder) then a different core could be needed.

If your pressure tank is one that uses an internal bladder, a standard automotive valve core will work fine.

Watch out: if WATER is leaking out of the air valve on a tank that uses an internal bladder, then the bladder is leaking.

 

Question: hole in the water filter?

(July 20, 2015) (mod) said:

Correy Smith said:

A couple of water filters seem to have a hole, how would I be able to fix that? Just now my wife made me aware of the filters and it looks like it's too late to fix them since the whole has been leaking way too much water. My guess is that there has to be a way to fix it and run a water treatment test on it.

Reply:

Correy, if the hole or leak is in the canister for your water filter, that part needs to be replaced.

See WATER FILTERS, HOME USE

Question: water heater expansion tank - relief valve is leaking

(July 30, 2015) Linda Crawford said:

We have an ultimate water heater with an expansion tank connection. We have noticed that the pressure release valve on top is leaking quite a bit of water. (around 3/4 of a quart). We had the tank replaced in 2013. It did not use to leak like this. Help! What do we need to do?

Reply:

Linda

Help for your problem is at RELIEF VALVE LEAKS

Watch out: a leaky relief valve is dangerous and could lead to a serious BLEVE EXPLOSION - search Inspectapedia.com for that phrase to read details.

Question: delivering pressurized water to outbuildings

(Oct 8, 2015) Seth said:

Hi, I was plumbing water to another out building and was wondering if I plumb the water line in between the water pump (well) and the pressure tank, will my water be pressurized? Or is it bad for the system?

Reply:

It depends, Seth. If your water system uses a check valve between the pressure tank or house water inlet and the well piping then pressure on the house side won't be delivered to an outbuilding teed off of the well line.

It may be possible to add a second pressure control and tank at the outbuilding. I'd discuss that option with your plumber.

Or you could feed the outbuilding from the pressurised side of the house water piping.

Also if the piping is long, small diameter, with many bends, the flow rate could be poor.

Question: how to drain a water tank

(Oct 11, 2015) dave said:
My holding tank broke free from the pipes, How do I drain the tank to make it able to move??

Reply:

Dave, if your pressure tank broke free from its piping it should drain completely out of the broken pipe. If it doesn't I worry that there's a burst, waterlogged bladder in the tank.

See WATER TANK DRAIN VALVE for instructions on how to drain a water tank.

Question: jet pump takes too long to pressurise the water tank

(Oct 28, 2015) Brian said:
My jet pump takes 15 minutes to pressurize and refill my 20 gal. pressure tank from "cut in" to "cut off" (30-50 lbs). Air is also visible in the clear hose connection from the pump outlet to the pressure tank (bleeding the line doesn't correct this).

When taking a shower water pressure drops to 40 lbs. in 1st. 15 seconds then slows to 37 lbs. in 30 seconds, 35 lbs. in 55 seconds and then to 30 lbs. at 2 minutes, before pump comes on for another 15 minute cycle. Also, if you continue using water when pump cycles on you will eventually run out of water. What could the problem and solution be?

Reply:

Hi Brian.

I would be looking for

- low water or poor flow rate in the well - this is the most likely problem - as I elaborate below
- pump set higher than needed above well bottom in a well with a small static head and poor flow rate
- a leak in well piping

It's normal for water pressure to fall during the period of water use when water pressure is being delivered by the air charge in the pressure tank.

Once the pump kicks in the relationship of that to water pressure depends on the pump delivery rate (gpm), lift, piping diameter, and of course the usage rate or flow rate possible at the fixture. In a modest-capacty home system and if the usage rate is fast enough that the pump can't "get ahead" of the fixtrure flow, then the water flow rate may be steady as long as the pump keeps running.

The fact that you run out of water suggests that the root problem is that your well has a poor recovery rate.

(Oct 28, 2015) Brian said:
Thanks Dan, your response makes a lot of sense.

Question: low water pressure after installing new water pump

(Apr 21, 2016) TRACY said:

LOW WATER PRESSURE AFTER NEW PUMP? About a month ago my submersible well pump went out. The pressure switch, pressure gauge and pump were replaced. The filter housing is about 2 years old. The pressure tank "appears" to be ok, so it was not replaced. The tank has 26 psi empty. The pump cuts in at about 31 psi and off at about 50 psi. The old pump was a Water Ace 1/2hp, never found the gpm. The new pump is a Countyline 1/2hp 10gpm.

What am I missing? Before the pump went out I had good pressure, now it is seriously less. The dishes don't get clean in the dishwasher and a shower is pathetic.

Reply:

Tracy, there could be various problems: pipe clogs, faucet strainer and shower head clogging, mineral deposits, well pipe leaks, low voltage to the pump; the GPM does not tell us the maximum pressure that your new pump can reach.

Search InspectApedia.com for DIAGNOSE LOW WATER PRESSURE to read a detailed diagnostic approach.

Question: water pressure surges after replacing water pump

(May 3, 2016) Jake jackson said:
Hi,I have a well that is 46 years old . last year I had to replace the pump for the first time . and now the water surges . I'm thinking it's the bladder tank ? But it's buryed in the ground what can I do ?

Reply:

I'd start at WATER PRESSURE PROBLEM DIAGNOSIS TABLE

Question: let air out of water tank when winterizing a home?

(May 3, 2016) Sid Johnson said:
Do you let the air out of the bladder when you winterize your home.

Reply:

No but you would want to let water out if you're leaving heat off.

See WINTERIZE - HEAT OFF PROCEDURE

Question: water pump can't keep up with sprinkler system

(May 7, 2016) Randy said:

Ppurchased a home recently, previous owner was using current set-up with no issues. When i turn on any zone in my sprinkler system, pressure in my tank drops down and pump kicks in. but never fills tank and doesn't keep up with sprinklers, pressure gauge shows about 15 PSI.

I have excellent pressure at the heads for about a minute, then they drop down to nothing. (4 heads on a zone). When I shut down sprinkler system, tank fills back up and everything works fine as far as house plumbing. Pump is a 1/2Hp about 50' deep. Is this a pump issue, well issue or tank issue. Neighbor has same set-up, they installed together and he has no issues. Sprinklers run fine.

Reply:

Randy, I suspect that the water flow rate into your well (its recovery rate) is slower than the pump's output rate. Some pumps or pump controls include a protection circuit or device that prevents the pump from continuing to run or limit its outflow rate when the water level drops in the well - otherwise the pump is likely to be destroyed by running dry.

Start by asking your well company to check the well's recovery rate. Search InspectApedia.com for WELL FLOW RATE TEST to read details.

Question: does bladder tank prevent shallow well pump from priming?

(June 22, 2016) PATRICIA said:

Will my bladder tank prevent my shallow well pump from priming. Been working on it for 3 weeks and unable to prime it. Replaced everything including pump and still unable to prime. Any information would help. Thanks.

Reply:

Doesn't seem likely. If the pump turns on in response to a drop in water pressure then the tank and pressure switch are not the problem.

Search InspectAPedia for HOW TO PRIME THE PUMP and try those methods. Follow the water, find the leak.
Check the pump impeller for damage

Question: Pump is kicking on and off

(July 11, 2016) brenda said:
my pump is kicking on and off. I have replaced the pressure switch and we took out the tank and drained it. How do I know if I need to replace my take? How do I know if the blatter is bad?

Reply:

If your tank uses an internal bladder AND the pressure tank is waterlogged OR if the pump cannot push water into the tank interior (or bladder -as can happen if the bladder has become stuck to itself) then you'll need to repair or replace the tank.

Very rapid pump cycling on and off typically is caused by a water-logged pressure tank or a new tank with a bladder stuck to itself or a similar condition that's not letting water into the tank.

See WATER PUMP SHORT CYCLING - to diagnose this problem.

For a description of water tank bladder being stuck and preventing water from entering the tank

see WATER TANK BLADDER STUCK to ITSELF

Question: Utilitech Water Tank troubleshooting & repair: gauge falls to zero

(Aug 17, 2016) Chris said:

New Utilitech 20 Gallon Water Tank (Lowe's). Bringing up and "stress-testing" a completely new system. At one point I completely discharged all water from the tank, removed power from the pump, and opened faucets to release any remaining system pressure.

Then, to isolate the tank completely, I closed a shutoff valve between the tank tee and the system.

Here's the weird part. The pressure gauge at the tank tee naturally read zero upon draining it completely. HOWEVER, after a few minutes, the pressure begins to creep up and eventually equals the tank precharge pressure (currently at 38 PSI).

Is this a natural phenomenon (perhaps due to temperature change), or is there a pinhole leak in my new tank allowing precharge air to transfer across the diaphram to the "water side"? The pressure at the top of the tank continues to read 38 PSI, but since the difference in volume on either side of the diaphragm is so great, I assume it would take a long time for pressure loss from a pinhole leak to be readable on a typical tire pressure gage.

Reply:

Chris:

An empty water tank that uses an internal bladder will have an air charge above the bladder equal to the tank pre-charge pressure (38 psi by your note). Perhaps air in the water-containing area of the tank is thus being pressurized by the pre-charge?

If there's a leak in the bladder I expect air discahrge to show up at faucets but perhaps the air leak is so slow that the air discharge isn't noticed.
But if the bladder leaks then ultimately I expect to see the pump start to short-cycle and I expect to see the draw-down water quantity reduced (before the pump turns on).

A second reason for a gauge to respond only slowly to pressure changes is debris-clogging of the gauge's sensor port; if you replaced the tank but are using an old gauge on the system that could be the case. Watch the gauge when you pressurize and de-pressurize the tank. Does it sometimes stick or is it slow to respond?

Finaly re "closing the valve between the tank and the system" - I'm unclear on this. Is the tank isolated from the pump and controls but still connected to the house water supply piping?

I'd try to separately isolate the tank from 1. the pump side, 2. the house side, 3. both sides. That'd be diagnostic.

(Aug 17, 2016) Chris said:
Thank you Dan.

"I'd try to separately isolate the tank from 1. the pump side, 2. the house side, 3. both sides. That'd be diagnostic."

I may have described the sytsem state unclearly, but yes, the tank is completely isolated from any and all plumbing systems. It is basically stand alone and capped off at the tee by a shutoff valve. In this state, the empty "water side" of the tank (as measured at the tank tee pressure gage)slowly creeps up in pressure until it equals the "air side" pressure. Currently set at 38 PSI. The entire system is weeks old, so no sediment here.

Unless there is a known phenomenon wherein the pressure on the water side of the tank would increase due to temperature changes, I can only otherwise attribute it to pressure bleeding across the diaphragm. UNLESS I am missing something that an experienced plumber would find obvious. :) And I am prone to missing the obvious!

(Aug 17, 2016) Chris said:

Dan. Regarding the water-side tank pressure increasing, while isolated from all plumbing: It was indeed the temperature differential causing the pressure to creep up. As the well-water-chilled bottom of the tank climbed up towards ambient temperature, it was also increasing in pressure.

Once the whole tank was equalized at the same temperature, I released any remaining air pressure from the bottom and re-isolated the tank from all systems. At this point, the pressure at the tank tee remains at zero as it should, and no longer creeps up towards pre-charge pressure.

It was the temperature difference. Case closed. In case you ever get a similar question, you can now say, "yeah, that's a thing." :)

Thanks again.

Chris

(mod) said:

At the start of this article and in more detail at WATER TANK BLADDER CONSTRUCTION where we show a cutaway of one version of a bladder-type pressure tank you'll see a small VENT hole in a metal dome that separates the water-holding area of the tank (in the tank bottom) from the air reservoir area of the tank (in the tank top).

When you empty the tank of water the bladder collapses downwards and the water pressure falls to zero or near-zero; there may be a tiny bit of water left in the system or if the water side was drained air could have entered the water side of the pressure tank.

Here's an image inspectapedia.com/water/Water_Tank_Bladder_416_DJFs.jpg

When you totally isolate the water tank, the air at the pre-charge pressure passes through that vent opening and slowly pressurizes the bottom or water area of the tank. That might be pushing enough on the bladder that if there is air or water remaining in the isolated bladder space you'd see the water-side pressure go up to the pre-charge pressure. That sounds OK to me.

When the tank is re-pressurized using this approach, and you see pressure on the water side, open the Tank Tee valve and see if some water or air comes out; a small shot should emerge, then nothing further. If air keeps coming out then yeah the bladder has a leak.

Question: Varem bladder pressure tank short cycling

(Aug 28, 2016) David said:

I have a 2 year old Varem bladder pressure tank with the pump and pressure switch mounted on top, the pump draws water from an outside tank.

The system works well at first then over a period of about a month it starts to short cycle.I then drain the pressure tank re connect and again all is well but it will gradualy start to short cycle after some weeks to the point where I need to drain the tank to "reset" the system.

I considered blocking of the pump/pressure switch pipes by sediment however simply disconnecting them to flush water through did not have the desired effect,only completely draining the tank and re pressurising with water will temporarily solve the problem.

Reply:

David,

Usually if the pressure control switch is debris blocked you'll find that it simply doesn't turn the pump on or off when it should.

Conversely, short cycling is usually due to a waterlogged pressure tank.

I'd take a look at the pressure tank's air volume control, or if it's an internal bladder tank, the bladder may be damaged; Replace the bladder or the tank in that case.

Question: Pump pressure Cycling at 30-57 . Old system cycled 30-52 .

(Oct 12, 2016) Ron said:

Just replaced 35/82equivent tank with 36 gal. Pressure was set at 28. Cycling at 30-57 . Old system cycled 30-52 . Is this OK?

Question: Do I need to bleed air out of the pressure tank so that it can fill?

(Oct 24, 2016) Lynn said:
When filling a brand new tank (pump is 30/50 tank psi set to 28), what about the air already in the water portion of the tank during filling. Is there a way to bleed that out when filling? Note: I'm not talking about the air in the bladder portion. Is there supposed to be air in the bladder (28psi) and air in the water portion both?

Reply:

Air already in the tank, without water, won't hurt you a bit. The bladder will be pretty much empty, and closed down upon itself - picture a collapsed balloon.

Set the air pre-charge pressure with no water in the tank - to 2 psi below the pressure switch cut-in pressure. 28 PSI would be just right for a CUT-IN pressure of 30 psi.

If there is un-wanted or excess air in the water-portion of the pressure tank it'll either absorb into the water or be discharged out through plumbing fixtures.

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