Water Tank Air Volume Diagnostic FAQs

Too Much Air - Pressure Too High in the Water Pressure Tank

Water tank is getting too much air pressure

well tank keeps getting over pressurized with air On 2016-11-29 by mike

by (mod) water tank keeps getting over-pressurized

Mike:

Look for an air volume control system that's not working properly. For example the Snifter valve system on older bladderless pressure tanks and used with submersible well

pumps uses an in-well air admittance valve and an aboveground excess air bleeder valve - either of which could be present and malfunctioning or even not needed if a new bladder type pressure tank was installed.

Use the search box on this page to find our article on SNIFTER VALVES to read details.

A leak in the internal bladder of a pressure tank that uses bladders can also result in increasing pressure in the system.

Air Volume Control Installation Q&A

General Procedure For AVC Installation or Replacement

Air volume control replacement is basically a bolt-on repair at the water pressure tank, once you've drained pressure and enough water from the tank that you don't get squirted during the removal and replacement.

The following Brady AVC control installation suggestions are a direct quote from the manufacturer whose contact Information I'll give below

1. Check the system for leaks. Your Air Volume Control will not replenish enough air to overcome leaks in the system.

2. Make sure that the side of the control marked “tank side” is closest to the tank. The control will not function otherwise.

3. Your Brady Air Volume Control should be installed into the 1/4” or 3/8” N.P.T. tank port above and closest to the discharge port as shown below.

4. Connecting the tubing (vacuum line) to the suction port located at the center of the control and the suction port on the pump. You Air Volume
Control works on a vacuum principle, so make sure that the tubing connected to the pump is clear and not obstructed or kinked.

5. A snug fit is all that is necessary for all connections. Do not over tighten!

6. For best results and easy installation, use the Brady UK-1 Installation kit.

Contact the manufacturer if you need parts, the installation kit, or more help:

Brady Products Inc., 2151 Logan Street, Clearwater, FL 33765 U.S.A. Tel: (727) 443-4508

Brady air volume controls controls are sold at plumbing suppliers and at building supply stores such as Lowes or Home Depot and cost about $35. U.S.

Please also search InspectApedia for and read AIR VOLUME CONTROL REPAIR

Is changing a water tank AVC twice a year normal?

A Friend of mine has to change his AVC about twice a year is this normal? - Tom

Reply: no, look for debris clogging or improper installation

Not in my experience, Tom; if the AVC keeps needing replacement I wonder if there is debris in the water that's clogging it up. Or maybe an improper installation?

Air Leaks at the Air Volume Control

Air is coming out of my water pressure tank - is that normal?

I have a lot of air coming out of the pressure tank (a bladderless with an WJ Type ACV).

There is an adjustment screw on the ACV. Which way do I turn it to stop the surging of air into the household water? - Dave M.

Reply: hissing at some air volume controls is normal excess air escaping

Dave, there are adjustments on some air volume control valves, but to be confident we know what action to take we need to diagnose the cause of the excess air.

For example, if you are constantly getting air blasting out of plumbing fixtures the root cause could be a leak in well piping - not something to fix by just adjusting the AVC.

Indeed some AVCs will vent excess air in the pressure tank. This design is particularly common on water pressure tanks whose air volume control is maintained by a snifter valve

(see SNIFTER & DRAIN BACK VALVES) because the snifter valve system can indeed push more air into the pressure tank than needed.

So if your water system uses a submersible well pump with a snifter valve, you will probably find a rectangular type AVC control on the side of your water pressure tank at about mid tank height, and it may occasionally vent air - that's actually normal, as we explain

at AIR VOLUME CONTROLS, Hissing.

What causes hissing at the air volume control?

I just installed a new AVC. If my cut-in pressure is 30 and my AVC unit is set to 25, I should hear hissing out this until the float closes the valve, correct?

I don't hear a thing ever. The only thing it could be is the water level never goes down far enough? (Apr 8, 2014) AVC - WJ

Reply:

You didn't tell us the brand and model air volume control, WJ; in some cases you will never hear air hissing unless there is excess air in the pressure tank.

Reader followup

It's an AMETEK-WJ store. The air is noticeable when ever it fills. It's not bad, but when you are running the water out of the faucet and the pump cycles, we get air out the faucet.

Reply:

AVC-WJ

First read AIR VOLUME CONTROLS, Hissing

and then see AIR DISCHARGE at FAUCETS, FIXTURES

Air is surging out of faucets after tightening up the air volume control

I recently had to repair a small pinhole leak in the cold water line to my kitchen sink.

To do so I had to shut off the well pump/water supply. After the repair I turned everything back on and then discovered a dripping leak from the air release valve on the tank's WJ type AVC and water spraying out from the snifter valve.

I tightened up both valves to stop the leaks and thought all was fine but a day or two later we began to get air surging at the toilet and other fixtures.

This seems to occur for a minute or two after the pump starts up.

I have not noticed short-cycling and the pressure gauge cut on and cutoff points seem OK(32 and 52psi respectively)and the tank seems to hold pressure OK as well. Any ideas/suggestions would be greatly appreciated. Thanks. Tim B. 5/3/12

Reply: replace the defective air volume control on the water tank

Tim,

Sometimes when we tighten fittings on the air volume control to stop a water leak we are also stopping the valve from being able to purge excess air - sending that excess air out at the faucets.

If the water system uses a submersible pump and an in-well snifter valve that admits air into the system, that design can admit more air into the pressure tank than is needed.

If the excess air can't be released at the aboveground AVC it heads for the faucets. Try replacing the leaky AVC that you found on your water tank.

Air coming out of faucets after fixing a pump

I have a bladder tank; and I recently changed the well pump after 25 years of use.

Since then air has infiltrated my system with spurts of air. Any advice would be truly appreciated. Thanks! 2/1/2014 Richard

Reply:

Rick,

About air discharge in the system after changing a pump, I would look for an air leak into the system or a bad air volume control, or a snifter valve that should not be in use with a bladder tank.

See AIR DISCHARGE at FAUCETS, FIXTURES for step by step diagnosis and repair details

Water Leaks at the Air Volume Control on a Water Tank

Water leaks at the AVC when the pressure drops off

Hello, I was wondering if someone could tell me what this is on our 82 gallon pressure tank.

When the pressure drops it leaks water at around 40 # . It also sounds like it is sucking in air. This only happens when i run the sprinklers.

The well will put out about 12 gallons a minute. But i have the pressure set at 45 and 65. It only takes 8 gallons of water to drop the pressure from 65 to 45 and that is when the pump comes on.

Is this some kind of automatic valve? is there a way i can stop the spitting of water or is that necessary.

I do not believe this tank has a bladder. It looks like it has a Schrader valve in that thing on the side of the tank.

But that is out side the well house on the well side of the check valve along with the pressure relief valve. I thought the pressure relief valve should be on the tank side of the check valve.

I do not think much of the man who installed this 3 years ago as he wants nothing to do with it now, So i need to figure this out. I will be changing the heads on the sprinklers to use less water. But the largest zone only uses 10 gallons a minute.

Thanks to anyone who can help, and i think your site is great. Bruce W

Reply:

Your photo shows a rectangular type air volume control on a water pressure tank - details and more photos of that device are found in the article above,

at WATER TANK AIR VOLUME CONTROLS

The valve should not spit water - it is doing so probably because your water pressure tank is waterlogged -has lost its air charge -

see WATER TANK AIR, HOW TO ADD - for various methods for adding air, including using the Schrader valve and an air pump

And yes Bruce, you are correct, this type of air volume control is used on water pressure tanks that do not use an internal bladder.

Your photo showed a steel water pressure tank with a pressure gauge and air volume control mounted on the side of the tank.

Your valve does not include a tube connecting it to the water pump as other air volume controls sometimes used because your model uses an internal float that opens and shuts a valve to allow air to enter the water tank. I often find these valves just stop working, because of debris clogging or because the float is stuck.

You can leave the valve in place and add air manually or you can replace the device.

Converting to a Bladder Type Water Pressure Tank: Changes to Air Volume Controls, Snifter Valves, etc.

Do I need a AVC on a new tank thats has a bladder ?

Do I need a AVC on a new tank thats has a bladder On 2018-12-24 by trustee37.mj

by (mod) - No

No Trustee.

An internal bladder type water tank keeps the air charge separate from the water - usually the water is in the bladder and the air charge above it. So air isn't absorbed into the water and does not need to be maintained.

I replaced my old water tank - what was that old 310WJ for - do I need it?

I just replaced my 20yo galvanized bladderless tank with an identical one from the same mfr. (yes, still being made).

I was impressed with the longevity of the old tank - I called her "Old Ironsides". I simply copied the identical piping configuration onto the new tank with new fittings.

Two fittings I "scabbed" from the old tank however, were the 310WJ (as pictured above with attached air pressure gauge) and a brass Flowmatic check valve with two inlet ports. The two inlet ports (on the tank side of the check valve) were being used for a air inflater stem (with cap) and the Pumptrol electric well control valve.

Over the years, I have just emptied the old tank completely with a garden hose annually and been happy enough with the performance.

My question is: I did not know that the 310WJ was anything more than a pressure gauge until I removed the old one and saw the rusted off float arm, apparently long since useless.

According to your description, the 310WJ was to allow excess air to drain out when too much was put in by an air inlet.

The only place an air inlet could have been would have been the air inflator stem, which I thought was only for adding air by mechanical means. It really does just look like an ordinary tire pressure stem and not like anything automatic.

Did I misunderstand what this was all along by keeping the cap tightly in place?

This is more just for my understanding than the thought of me trying to resurrect the old air volume control valve scenario

- I can't imagine the old 310WJ would last very long in any event. Also, my old system (now rebuilt) absolutely had no pressure relief valve unless one is hidden along with something else - on the output side is just a boiler drain for draining the system along with a common stop valve before being connected directly into the house plumbing. Should I worry? - Dan 3292

Reply: bladderless water tank + submersible pump + snifter valve: need changes when replacing the water tank

Dan,

in SNIFTER & DRAIN BACK VALVES we describe a type of air volume control that was used on some wells that use a bladderless type water pressure tank along with a submersible pump. Because during well pump on and off cycles,

the snifter valve system (there is a companion device in the well) can admit more air into a pressure tank than needed, that rectangular device on the side of the old pressure tank included a vent that would automatically vent out excess air when needed.

Because you replaced your old bladderless pressure tank with a new bladderless tank, if you intend to continue to rely on the snifter valve system, you'll want that air vent to work properly or your water system may begin to see too much air.

See AIR DISCHARGE at FAUCETS, FIXTURES

Of course if the in-well valve or the snifter valve have quit working, you can go back to manually adding air to the water pressure tank when needed, but honestly it's better if that chore is handled automatically.

Watch out: for readers replacing water pressure tanks: if you are changing from a bladderless water pressure tank on a submersible pump well system, check to see if your old system included a snifter valve system that needs to be properly removed - details are

at SNIFTER & DRAIN BACK VALVES

Reader follow-up:

I have owned the house and well pump tank for 17 years now - only 3 years after the sticker on the tank said that it was installed by our local well driller.

I don't think I ever heard the 310WJ AVC ever hiss to release air in all my years here, and the snifter valve (that's a new one on me) has had it's cap tightly screwed down for years

- even with Teflon tape around it as it used to leak water on the floor. This tank has been relocated around the basement maybe four times (all by me).

That said, I am really doubting how much the air volume control ever worked. I have never experienced excess air in the tank to the degree of getting air coming out of the faucets

- more the reverse that I got short cycling of the pump from not enough air, so I started an annual program of draining the tank in the fall. I see that the AVC 1-1/4" opening on the tank is approximately half way up, implying that tank is meant to basically ever be half full of water, half full of air - another revelation.

So my tank which is marked 42 gals. pneumatic actually only holds about 20 gals. of pressurized water?

I only have ever used the snifter valve to connect a small electric air compressor to aid in speeding up the annual draining process.

I stupidly thought that was what it was for. Also, I have discovered that in times of extended electrical outages where I do not have 220v service, but do have my 120v generators -

I can "pump up" the tank with my air compressor to revive my water service. Very handy for those multi-day outages!

What about the issue of not having a pressure relief valve?

BTW: Thanks so much for keeping this website! I rebuilt my septic system this summer and referred to your articles on septic theory over and over.

Reply:

Dan3292

When an automatic air volume control system on a water tank is not working, it means simply that on occasion we have to use some other means to restore air to the tank, lest it become waterlogged and give us a pump short cycling problem.

Your second question: the risk of not having a pressure relief valve (required by code) on a water pressure tank is that the tank could burst, not only flooding the building but injuring someone. This problem would occur, for example, if a pump control failed to operate properly or were mis adjusted by someone.

See WATER TANK PRESSURE RELIEF VALVE to read details.

Signs of Failed Air Volume Control Valve - AVC

Short cycling water pump, plastic bowl type AVC - where does the AVC get its air?

My water pump cycles on for about 8 seconds then off for about 35 seconds. I have replaced the (plastic bowl type) Air Volume Control.

I thought it was OK but it is back to cycling too often.

I have checked for tank leaks with soapy water but found none. What do you think would cause this?

Where does the AVC get the air it puts into the tank?

Could the line from the pump to the AVC be restricted? - Wayne 12/24/12

Reply:

The air source depends on the air volume control type - but typically it's either from a vent on the control itself or in a deep well installation there may be a snifter valve on piping near the water pressure tank that allows air into the water pipes at pump-off cycles, working in concert with a drainback valve on the well piping in the well.

We explain this detail at SNIFTER & DRAIN BACK VALVES

Also see

• AIR LEAKS at the AIR VOLUME CONTROL - normal for some models
• WATER LEAKS at the AIR VOLUME CONTROL

 

Air Volume Control Adjustment

I changed a bad AVC, now there's no water pressure, pump won't come on

I have changed bad AVCs before but this time is a mystery.

My AVC was discharging water and needed replacement so I cut power to the well, drained some water off the 200 gal galvanized tank, disconnected the tubing at the AVC, unscrewed the AVC from the tank and installed the new AVC.

I did not completely drain the tank because there was water coming out of the fitting when I took out the old AVC.

I closed the drain valve at the bottom of the tank, turned the power back on and the pump ran for a little while and shut off. There is 60 lb pressure on the well and I do not have a gauge on the water tank so do not know.

There is almost zero water pressure in the house, looks like the tank has water in it because I removed the AVC again just to see if there was water in the tank.

Reinstalled AVC but no water to the house.

What did I do wrong. When I checked the new AVC installation, I took off the copper tubing and water was shooting out of the AVC so I screwed it back on.

Pump won't come on because pressure is already at 65 lbs and no water to the house or out of the hose at the bottom of the tank. HELP ! (Mar 27, 2014) phillip_rosenbaum@yahoo.com

Reply:

Phillip

Watch out: be sure that the water tank air pre-charge pressure at system startup is at least 2 psi below the pressure control switch CUT-IN pressure.

I suspect that's the problem.

Try turning off power and draining the tank completely. Then close tank drain and turn on the pump - assuming its a submersible pump, right?

You did make sure that water was turned on between the tank and the building, right?

I don't see how to adjust the US Gauge Type air volume control

I have read through all of your pressure tank articles searching for some details.

 I am not the first to ask this question as I see where others have asked the same question but never answered.  I don't think the correct answer is switch to a bladder tank as bladderless with the volume control can be found new for sale in most plumping stores in my area at high altitude mountains. It is very simple.

You have a well, deep or shallow and on your air volume control (bladderless tank) has a valve with an adjustment screw with no tubing.  

You are curious if adjusting this screw could eliminate or help troubleshoot extra air coming out of the faucets.

 If you choose to adjust the screw (troubleshooting or maintenance) to either let air pressure out or let air in, what direction on this screw provides these benefits?

Additional question is: I get air coming from faucets, showers, sinks and toilets equally when the pressure tank nears 30psi and begins to refill.  The cold side is always the culprit, and it is very difficult to ever detect if hot water, if ever, sends any air to the faucets.

 I never get any kind of hissing from the air control valve.  I am considering replacing the part US Gage 310WJ,  but don't want to waste my time if the above issues signal more conclusively something different. - Mike 4/5/2013

Reply:

Thanks Mike, I reviewed the article above and added details on adjustment as well as repair of these air volume controls.

Basically, if you're getting air hissing out of valves and fixtures in the home, and provided that your water system indeed is using an air volume control like the US Gauge float type controls above, the device is intended to vent excess air from the system.

Air is entering elsewhere at a snifter valve (SNIFTER & DRAIN BACK VALVES) or similar device, usually on the vertical water pipe riser inside the well. You may be able to correct the problem by simply following the adjustment procedures at AIR VOLUME CONTROL ADJUSTMENT

 

What does the float do in a water tank?

What does the float do in a water pressure tank? 5/26/14 Robert

Reply:

The "float" in a water pressure tank is probably referring to the small float that actuates an air volume control on a water tank that does not use an internal bladder.

For details see

AIR VOLUME CONTROLS, WATER TANK

in that article where we discuss the US Gauge & Similar Type 310WJ, Type 300SL, or Type 6 Rectangular Air Volume Controls = Excess Air Vents

On some AVCs the float can be adjusted to control the amount of air that is maintained inside the water pressure tank.

Diagnose Air Volume Control Problem Diagnosis FAQs

Installed New AVC but water tank is still waterlogged: pump is short cycling

I have a galvanized water tank, 5 ft tall probably 100 gallons and an above ground pump. I replaced the Brady AV 100 AVC last week because the water tank was water logged and the pump was short cycling on and off every few seconds.

All was well for a few days until it began short cycling again and I noticed water dripping out of the air port on the new AVC unit.

I'm assuming the new AVC unit is bad so I will replace it again. It is mounted on top of the water tank and has been for years. Is there a problem with the mounting location.(Mar 10, 2015) Ray Coker

Reply:

Ray just replacing the AVC, while a good idea, won't be very quick to fix a waterlogged tank. You probably need to put a proper air charge in the tank manually.

So before assuming that the new AVC is defective,

see WATER TANK AIR, HOW TO ADD

Set the air pressure in the tank to 2 psi below the pressure switch CUT-IN pressure.

Copper tubing on air volume control contains water?

Is water suppose to be in the copper tubing going into the diaphragm? Anonymous

Reply:

The tubing may contain water or air depending on conditions in the water tank. For example, if there is excess air to be vented through some AVCs the the tubing will certainly contain air.

 

How to test or check the air volume control mounted on 750 gallon water tank

I have an old (1967) large cylindrical bladderless galvenized steel tank (about 750 gallons). It has the typical air volume control located at the halfway point (radius of the cylinder).

Over the last few months I have been losing the air volume resulting in shorter and shorter cyclings of the well pump.

I have looked for leaks on the upper fittings but have not any (soap/water). How can I test the air volume control mechanism?

But also, how could it even be a source of a total loss of the air volume since it is only half the way up the tank? I really do not want to replace the tank. (Jan 23, 2015) John McKinsey

Reply:

John

That's a very large water storage tank with a large volume of air charge. If you're losing air rapidly I'd look for a leak at the tank's upper portion just as you did.

AVC testing, if any is poossible, depends on the type of air volume control installed. Use our email found at our CONTACT link to send me photos of your control if you like .

Meanwhile you can note the point on the tank side that marks the top of the water level - and thus the bottom of the air charge when the pump has shut off. If that line (say looking for condensation or feeling for temperature difference) is near the tank top, add air and note how long that lasts.