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How to Find & Repair the Water Tank Air Volume Control Device InspectAPedia®  -       How to Find & Maintain the Water Tank Air Volume Control - what it looks like, when do you need one, or is an AVC even installed on your water tank? Photographs help identify air volume controls; How to replace or abandon an air volume control What is a snifter valve used on a well water system and how do they work? Hidden and antique air volume control valves and features Well pump rapid cycling diagnosis & repair procedures Questions & answers about air volume controls on water tanks: how they work, why they are needed, and how to fix, repair, replace, or abandon an AVC that is not working, hissing, leaking, or just generally making trouble.

This article describes water tank air volume controls (AVCs) used to keep a proper air charge in a water pressure tank and thus avoid well pump turning on and off to frequently. We describe what AVCs look like, we explain the types of air volume controls used on jet pumps and on submersible pumps, and we describe where to find them, and how these devices work, and how they can be repaired, replaced or just abandoned.

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WATER TANK AIR VOLUME CONTROLS - Defined, How they Work, How to Use

If you are having trouble with the air charge in your water pressure tank or are diagnosing lost water pressure, bad flow, or water pump short cycling, see WATER PRESSURE LOSS DIAGNOSIS & REPAIR, and WATER TANK REPAIRS, and WATER TANK AIR, HOW TO ADD. Readers of this document should also see Water pump and pressure tank repair diagnosis & cost an specific case which offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost.

In water pressure tanks that do not use an internal bladder, over time, the air in the tank will be absorbed into the water and the tank will become ‘waterlogged’. This means that the tank is full or nearly full of water. The pump will come on and off very quickly (short cycling or rapid cycling water pump). This short cycling is hard on the pump, and air is added to the tank to correct the situation. - Adapted from Carson Dunlop Associates Home Reference Book.

The job of the AVC is to keep air in the water tank to avoid waterlogged water tanks or well pump short cycling.

The air volume control or "AVC" device mounted (usually) on older steel water tanks (ones that do not use an internal bladder to keep water and air separate) is designed to automatically add air to the water pressure tank when it's needed.

If a water tank loses its air charge it stops working properly and usually results in the water pump turning on and off rapidly - "short cycling" of the water pump. This condition, in turn, can damage or even burn up the water pump.

Round Air Volume Control Devices With Copper Tube

An "automatic" air volume control (AVC) device may be installed on the water pressure tank if it's an older, bladderless steel tank. The AVC is intended to automatically put a little bit of replacement air into the tank from time to time as water pressure cycles up and down, that is, each time that the water pump runs.

If you see a round steel disc of about 4" diameter and about 1" thick on the water tank, mounted perhaps at the middle of the tank height or at the water outlet to the tank, or perhaps on the side of the tank with a plastic or copper tube connecting the disc to a fitting on the tank or nearby piping, this is the AVC.

Used on jet pump water supply systems, on each pump "on" cycle the AVC draws in a small volume of air that is then pushed onwards into thte water pressure tank. The tube connecting the AVC to the pumping chamber suction side provides the pressure drop that pulls on a diaphraghm on the AVC that in turn causes the AVC to draw in its air charge.

The air volume control might be found on the side of the water tank (above left) and is typically connected to the water pump itself (above right) by a flexible copper tube. The AVC may also be located right on top of a one line or two line jet pump such as is visible at the top center in our Meyers™ well pump photo at left. The alternative air volume control shown below does not include a disc-shaped device and has no connection to the water system's pump or other piping. The hole seen in the end of the brass screw is the air inlet for this air volume control.

Rectangular Air Volume Controls With No Copper Tube - Air Vents

The deep-well AVC below does not use copper tubing, all it's parts are self-contained. This is a valve that you may hear hissing if it's working. The gauge shown is a common model, the U.S. Gauge Type 300L (for shallow wells) or Type 310WJ (for deep wells) Air Volume Control produced by U.S. Gauge, also located under the Ametek® brand. As we discuss at Snifter Valves below, some of these valves function only to release excess air in the water pressure tank; in that case air is obtained from other components (such as the snifter valve). .

Our photo (below left and right) shows a U.S. Gauge Type WJ - so we know this installation is for a deep well.

As U.S. Gauge points out,

U.S. Gauge Air Volume Controls are designed for domestic water supply systems which deliver a quantity of air to the pressure tank with each cycle of pump operation.

Insufficient air in the pressure tank causes frequent operation of the pump.

Too much air in the pressure tank will permit large bubbles to be carried into the piping system. This causes a disagreeable noise and sputtering at the faucets. It is the function of U.S. Gauge air volume controls to maintain the correct relationship between the volume of air and the quantity of water in the pressure tank.

As we illustrate below, this air volume control device uses a float that moves as the water level inside the water tank changes. The float movement allows air into or out of the water pressure tank as needed.

Watch out: Only the deep well model AVC from U.S. Gauge, the device excludes the tube connecting from the AVC to the well pump and you won't see the brass fitting on the bottom of the shallow-well AVC model illustrated at Can I Replace a Round Diaphragm AVC ....

Here's one more photo of a (probably not working) air volume control attachment on a water tank, to help you recognize just what these devices may look like. Does My Water Tank Use an Internal Bladder? Not if It's Using an AVC. Remember if you see this device on your water tank, the tank is not a bladder-type or "captive air" or "Well-X-Trol" ™ type water tank. It's an older steel water tank wherein the air charge is ultimately lost either by absorption into the water passing through the tank or by leaks. On a water tank that uses an internal bladder (keeping water and air separated), the air charge is not normally lost and the air volume does not normally need adjustment. And you couldn't retrofit one of these devices anyway - no place to mount it, and no room for the float to move - just no way.

Snifter Valves & Air Inflators: "Hidden" Air Volume Control Valves: AVCs, Advanced Water Tank Air Volume Control Designs, More AVC Identification Photos

Snifter Valves, Air Inflator Stems, & Drain-Back Vents for Air Volume Control in the Water Pressure Tank

Snifter valves are a two-part air volume control system designed to maintain the air charge in a well water pressure tank on some submersible pump systems where a bladderless water tank is installed. Snifter valves, used only on submersible well pump systems (the pump is inside the well), are a type of automatic air volume control system that adds a charge of air into the water pressure tank during each well pump on-cycle. Snifter valves provide an air inlet, typically located on a check valve on the water line near the bladderless water pressure tank. The air inlet work in concert with a water drain-back valve (a bleeder orifice) that you cannot see - located on well piping inside the well where a submersible pump is used. In our snifter valve photo (left, Rasmussen Well Drilling, Inc., Two Harbors MN & DJ Friedman) ) my finger points to the stem of the air valve portion of the snifter valve; the valve is mounted on a bronze check valve. Stains on the floor show that there has been leakage at this valve. At the end of a well pump on-cycle (when the well pump stops) the snifter air valve mounted on a check valve on the well line ahead of water pressure tank opens to allow air into the well piping. Water drains out of the well piping at a bleeder fitting mounted on a tee on the well piping, inside the well. Later in this article we include photographs of the bleeder orifice drain back valve found on well piping where the snifter valve system is used. The bronze check valve (on which the snifter valve is mounted in our photo) keeps water in the pressure tank from draining back down into the well when the well pump has stopped.

Because the snifter valve system will usually push more air into the water tank than is needed, an air release valve mounted on the water pressure tank is also installed to purge excess air from the water tank as necessary. So if you hear air hissing from the air purge valve, that's normal. In our snifter valve photo (left) the green arrow points to the air release valve and the red arrow points to the snifter valve air inlet fitting mounted on a check valve. Watch out: The snifter valve stem looks like any other air inlet valve but it uses a weak internal spring to allow the valve to open on its own, admitting air into the piping. DO NOT tighten the valve stem cap found on the snifter valve. If you do so no air can enter the well piping and the system won't work. If you find water leaking out of the snifter valve it needs repair or replacement. You can temporarily tighten the valve stem cap to stop the water leak, but your water tank will lose its air charge, and until you've repaired or replaced the snifter valve, the water tank air will have to be added manually using other means that we describe at WATER TANK AIR, HOW TO ADD In our photo above the snifter valve had not worked for years and was also leaky. You can see the copper stains on the floor below the valve (my finger points to the snifter valve stem).

The Snifter Valve System Drain-Back Fitting

These air volume control valve components are located inside the well on a tee on the well piping above the static head or about ten feet from ground surface in most installations. When the submersible well pump is "on" this drain back valve closes and water rises in the well pipe and into the building water supply system.

When the submersible well pump stops running, the snifter valve air inlet located at a check valve near the water pressure tank admits air into the well piping. In turn that entering air allows water in the well piping to drain back into the well through the small opening in the drain fitting located on piping in the well.

When the submersible pump starts running again, water pressure closes the drain back valve. Our photos below show how these valves function to open and close in response to water pressure in the piping.

If the well pump is a submersible unit (located in the well) and if also the water pressure tank is a non-bladder type, there could also be one or even two air inlet valves installed on vertical section(s) of well piping inside the well. Our photo at below left (Rasmussen Well Drilling, Inc., & DJ Friedman) shows the tee where the well service company worker has removed the air inlet vent detailed in our photographs found below. Air inlet vents (sometimes more than one) are installed on the vertical section of well piping on older systems with bladderless pressure tanks as a means of adding air to the pressure tank at each pump cycle. The vent(s) are installed at a tee just above the top level of the static head of water in the well so that air can enter the vent during pumping cycles.

At the end of a well pumping cycle water drains out of the well piping section that is above the vent itself, permitting air to enter the piping. Water drains out and/or air is allowed into the well piping through the small orifice shown in the face of the air inlet valve shown at left. This is the valve we had removed from the well piping tee shown just above. At the start of the next well pumping cycle, water pressure inside the pipe closes the vent valve and air inside the piping is forced into the pressure tank. Older well piping air vents such as the unit shown here (removed from the well piping to permit close-up and internal views) used a captive bronze ball to open and close the vent opening and are reliable. Newer well piping air vents use a flapper design that Rasmussen reports are less durable. If the air inlet vent fails to close when the submersible pump is running, some water pressure, quantity, and flow delivery to the building will be lost.

Our well piping air volume control valve photographs below show the simple design of this well piping air inlet control valve. When the submersible well pump is off, pressure against the ball inside the air inlet valve is released, the ball can move away from the valve opening, and air can enter the valve. When the submersible well pump is on (pumping water), pressure against the ball inside the valve body closes the air inlet valve.

Snifter Valve Repair or Replacement

It's trivial to repair or replace the above-ground components of a snifter valve system as the parts are readily accessible. Be sure that you replace the internal snifter valve core with the proper parts. Using a valve stem core from an auto supply store may stop leaks at the valve but the spring will be too strong to allow the valve to admit air into the system when required - it will no longer work.

To replace the drain back orifice and valve shown immediately above it will be necessary to open the well and pull the well piping up sufficiently to reach and replace the device - a larger expense and more trouble as you can see in our photo (Rasmussen Well Drilling, Inc., & DJ Friedman). A well service rig including crane and winch are needed to pull the well piping.

Why are Snifter Valve Air Volume Control Systems Used

There are a few reasons why a snifter valve air volume control system may be used along with a submersible well pump, bladderless-type water tank, and check valve.

Rasmussen points out that in Northern Minnesata and on water systems in other very cold climates, the system's ability to drain water back into the well, leaving just air in the higher sections of well piping can help protect a well system from freezing.

On water systems whose well provides water high in smelly hydrogen sulfide (that rotten egg smell) or perhaps high in iron, the high absorption of air into the well water provided by this design helps oxidize and thus reduce those contaminants in the water supply.

By contrast, a bladder type water pressure tank keeps the water supply physically separate from the pressure tank's air charge - air is never absorbed into the building water supply and other treatment methods would be needed to remove sulphur, hydrogen sulfide, or high iron levels.

Converting a Bladderless Water Tank to a Tank with an Internal Bladder? Remove all the Snifter Valve Components!

Watch out: if on a submersible well pump system that uses a snifter valve for air volume control you later convert a bladderless water pressure tank to a tank using an internal bladder, you should remember to remove both the snifter valve located on the check valve near the water pressure tank and the bleeder orifice or drain-back valve located on the well piping.

Other Air Volume Controls on Large Water Storage Tanks

On some water storage tanks such as the antique 450-gallon tank shown at left (courtesy of reader Craig Revill), the air volume control may not be so obvious (photo below right). The device shown is (we should say "was") an air volume control produced by Penn Electric Switch Co., Des Moines Iowa. You could guess at the function of this device even if the manufacturer hadn't generously given an identification tag: notice the small diameter brass tube connecting the water tank to the well pump.

The patent for this air volume control switch was published in 1943 and patented by Burton E. Shaw. At left we illustrate (from the patent application) just how this air volume control switch worked. Here is the air volume control patent text and an explanation of how this AVC worked. Shaw explained this air volume control or AVC was intended as a deep well device - by this he probably meant not shallow or "dug" wells. The device was intended to be mounted in the wall of a water storage tank (as above) and adjacent to the water level in the tank so that the valve could respond to both air pressure and the water level in the tank itself. The valve relieved air from the tank when the water level was low as a result of excess air from the pneumatic head of the tank, but it would prevent the release of air from the tank when the working pressure inside the tank was below the required amount.

How to Maintain & Use the Water Tank AIR VOLUME CONTROL - air-volume controls on water tanks

How do we know if the AVC is working?

Our photo (left, courtesy of reader Doug Mehak) illustrates still another type of air volume control. The red arrow at the left of the photo points to the AVC and the right arrow points to the tubing connection on the water pump, in this case a one-line jet pump. In our photos above and at left, most AVC controls that use a pressure sensing tube connected between the AVC and the water pump. You will see a small diameter tube which connects the air volume control valve to a fitting (usually) on the water pump itself so that the valve can respond to the cycling on and off of the water pump (and changes in water pressure). If the air volume control valve is working properly, it uses the pressure changes caused by the cycling on and off of the water pump to automatically add air to the water tank when it's needed. Makeup air is needed in these water tanks because over time the air charge in the tank is absorbed into the tank's water. The most common versions of air volume controls, illustrated at the top of This article , look like a disk of about three inches in diameter, as we show in the photographs here. A copper or plastic tube that extends from the AVC to a fitting on the water pump itself, as we showed on the photograph above. Look at the fitting screwed into the side of the water tank about 2/3 of the way up from the tank bottom and on the right side of the water tank in the photograph above. If the air charge in your water pressure tank is not being maintained, either there is a leak in the tank or the AVC is not working. Usually the case is the latter.

Also illustrated earlier in this article, a second common version of air volume control valve is shaped like a small rectangular steel box with fittings shown in our two photographs above. You also can see the small object connected to the side of the water tank near the top right side of the tank in this photograph at left. There is no copper tube connected to this AVC. Here is a close-up photograph of this more rectangular type of air volume control. If this AVC is working you will occasionally hear air hissing out of the fitting, as we discuss belo.

How to Replace an Air Volume Control Valve

Can I Replace a Round Diaphragm AVC with a Rectangular US Gauge Type 300L or 310WJ?

Question:

I was wondering where I could get a Rectangular Air Volume control with no copper tube – D.W. Abingdon VA

Reply:

U.S. Gauge makes rectangular type AVCs, as we illustrate above. So do some other companies.

Watch out: rectangular AVCs like the U.S. Gauge unit shown above and illustrated here from the company's product literature, incorporates a float inside the water tank. If you look closely at our photos you 'll see that the gauge mounts through a 1 1/4" diameter ANPT threaded pipe connection into the water tank.

Also the mounting location of the gauge has to be correct - if your tank tapping is in the wrong place on the water tank, the float may not function properly. Check your water tank to see if there is a tapping in the right location. And see the AVC product instructions and check with the manufacturer's customer service before trying this swap.

Watch out: also to be sure to order the proper air volume control model. For example the U.S. Gauge AVC Type 300L is designed for shallow well operation, and the U.S. Gauge Type 310WJ Air Volume Control is designed for deep well operation. These devices do not work in an identical fashion, so buying the wrong model for your well would be a mistake.

The shallow-well U.S. Gauge 300L AVC, for example, does not eliminate the tubing connecting the device to the water pump. On this gauge, (photo at left, U.S. Gauge product literature), includes a brass fitting at the gauge under-side. You can see it in the bottom left of the photo at left. That brass fitting is an air inlet valve that connects through a plastic (polyethylene) tube to a snifter valve that is mounted on the well pump itself.

Depending on the AVC float position and operation, the snifter is a one-way valve that allows air into the pump and thus into the incoming water supply and into the water pressure tank. When enough air is in the water tank the float responds and closes the air inlet valve.

The deep-well U.S. Gauge Type 310WJ Air Volume Control, as we described and illustrated above at Rectangular Air Volume Controls, does not include this tubing connection for a snifter valve and its operation is a bit different. The Type 310WJ AVC for deep wells also uses a float inserted into the water tank interior. But there is no external fitting for a tubing connection.

A chamber inside the AVC uses an adjustable pressure relief valve to allow excess air to escape from the valve when the tank water level (and thus the float level) drops. That process explains the air volume control device "hiss" that we discuss at What is that Hissing Sound.

So if pressure in the tank exceeds the AVC pressure setting air is vented from the water tank. The device is adjustable between 15 and 40 psi, and is factory set to 25 psi.

Getting Rid of the Air Volume Control Valve

Install a water pressure tank that uses an internal bladder

If you convert from a non-bladder type water pressure tank to a water tank using an internal bladder, part of that installation will include the removal of any air volume control valves on the system, including an AVC that may be mounted on the well pump (above-ground jet pumps) or a hidden AVC that is found inside the well piping (submersible well pumps only).

Remove and Discard the Air Volume Control Valve

You can remove the AVC entirely, abandoning its automatic function, but if you continue to use a bladderless water pressure tank you will need to restore air into the tank from time to time using one of the other methods discussed in this article series: WATER TANK AIR, HOW TO ADD

If the the rusty, leaky air volume control valve does not work, can I just remove it?

The short answer is sure. Or if it's not leaking you can leave it in place, which is safer as it avoids disassembly and possible trouble sealing the fittings against water leaks. But if you abandon the air volume control you will occasional have to add air to the water pressure tank (WATER TANK AIR, HOW TO ADD) when the well pump starts to short cycle (SHORT CYCLING WATER PUMP) or turn on and off too often.

In 40 years of messing with plumbing I've rarely found an old AVC that worked reliably for long in a residential application. The AVC at left (that round thing in the center of the photo) was found by Langdon who found it to be rusty, leaking, and not working. He replaced it. An air volume control on a water pressure tank can be left in place but don't count on it to work. If the air volume control valve itself is leaking or fittings on its tubing leak, you may decide, as do many plumbers, to simply remove it. Just screw in a pipe plug where it was mounted on the water tank, and a smaller (usually brass) plug may be needed at the point of connection of the other end of the copper tube if one was installed on your system. (You'll have to turn off the pump and release water pressure and drain some water from the tank before replacing an AVC with a new one or with a pipe plug.) In rare cases an air volume control may put too much air into a pressure tank - see AIR DISCHARGE at FAUCETS, FIXTURES. If your AVC is not working or has been removed, and if your water tank is a non-bladder type system, you'll need to use one of the other methods discussed here for adding air to your water tank when it's needed. Forget this method for maintaining the proper air charge in a water tank, except for the Leaky Air Volume Control tip below.

What is that Hissing Sound Coming From the Air Volume Control?

Hissing Versus Water Leaks at AVCs

If you may hear air hissing in at this air volume control fixture (it's working). Hissing air at the air volume control means that the control is releasing excess air from inside of a bladderless water pressure tank.

But if you see water leaking out of the air volume control, that means it needs repair or more likely, replacement..

Here is a perspective view of where air volume controls are typically installed on a steel water tank. You won't see a control like this installed on a bladder-type captive air water tank.

Leaky Air Volume Control Tip: sometimes when you've taken water pressure off of the tank and are refilling it by air using one of the other methods below, you may hear a hissing coming from the tank.

Air may be leaking out of an opening at the base of the air volume control. It's valve parts may be partly "stuck" from having moved so seldom or having got clogged by debris.

Usually if this is happening you can simply push your finger over the hole where you feel air escaping.

Some air loss is common at this point, but it should stop on its own. If it doesn't, tap your finger on the hole a couple of times and the air hissing will probably stop. If not you may need to call a plumber to replace this annoying part.

Sometimes we tap the control (gently) with a wrench to see if this will stop the leaking. It has always worked for me - so far.

Watch out: we do not recommend trying to disassemble this valve. And its response pressure is factory set. If you mess with the brass lock nut and vent you are changing the operating pressure range of the air volume control valve.

Frequently Asked Questions (FAQs) about water pressure tank and well system air volume controls - AVCs - installation, diagnosis, and repair

Question: Why Can't I Find the Air Volume Control on My Water Pump or Water Tank?

I've looked all over my water pressure tank for that round disk thingie that you show in the photos in this AVC article but I just can't find it, nor do I see that rectangular version that is sometimes on the tank side. Where is it?

Reply: your well water system may not have an AVC, or the AVC may be hidden on the well piping inside the well

Bladder type water tanks (WATER TANK BLADDERS & CAPTIVE AIR) do not use an air volume control valve: Air volume control valves are present only on steel water tanks which do not include an internal bladder to keep water and air separated inside the water tank. In other words, if your water tank is one of the newer models which uses an internal bladder, you won't find an AVC installed.

A bladder-type water tank keeps the air charge separated from the water. The air is in the tank and the water is inside the bladder inside the tank. Thus the air charge does not become lost by absorption into the water.

Hidden AVCs that may be found inside the well are discussed at Air volume control valves located inside the well

Question: does it matter where the AVC is installed?

Does it matter where the avc is installed? i have a 1/4" opening 3/4 up from the base,probably used for pressure gauge,rather then use the 1 1/4" opening 2/3 the way up. - Schnitzl

Reply: Yes - here are some details about proper AVC location

Yes the AVC has to be installed at the proper location on the tank relative to the tank's moving water level - take a look at the instructions that come with your unit and you'll see that information, usually in the form of a sketch.

An opening up 3/4 of the way from tank base is probably OK but I'm not sure - it may depend on your particular type and model of Air volume control device. They vary.

In sum, the location of an AVC depends also on the type of device. For example on some submersible pump wells air volume in the pressure tank is controlled by a Snifter Valves mounted on well piping just ahead of the pressure tank, working in concert with a piping drain/vent located actually inside the well itself.

Question: water pressure is surging, bladderless pressure tank, what to do?

my water pressure is surging and i have a bladderless tank. Any tips? no drain at bottom of pressure tank! - Craig

Reply: check for short cycling water pump diagnosis & solutions

Craig:

I if your water pressure is surging in synch with the well pump turning on and off your water tank is probably water logged and needs its air charge renewed.

Indeed if your water system included an air volume control device (AVC) that has stopped working, the pressure tank may have become waterlogged.

Take a look at SHORT CYCLING WATER PUMP to be sure of correct diagnosis of the surging water pressure. If the problem is loss of air in the water pressure tank (very common), see WATER TANK AIR, HOW TO ADD for three different approaches to getting air back into that water tank.

Question: is changing a water tank AVC twice a year normal?

Afriend 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?

Question: 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 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.

Question: 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 inflator 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 the article above (see SNIFTER 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. (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 VALVES

Questions & Answers regarding this article

Questions & answers about air volume controls on water tanks: how they work, why they are needed, and how to fix, repair, replace, or abandon an AVC that is not working, hissing, leaking, or just generally making trouble.

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WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER PRESSURE PROBLEM DIAGNOSIS TABLE

WATER PUMP CONTROLS & SWITCHES
WATER TANK: USES, TROUBLESHOOTING
WATER TANK AIR, HOW TO ADD
  WATER TANK AIR VOLUME CONTROLS
    AIR VOLUME CONTROLS AVCs DEFINED
    AIR VOLUME CONTROLS ROUND/Tube
    AIR VOLUME CONTROLS RECTANGULAR
    AIR VOLUME CONTROLS FLOAT TYPE
    AIR VOLUME CONTROLS, Hidden
    AIR VOLUME CONTROLS, Hissing
    AIR VOLUME CONTROLS, MAINTENANCE
    AIR VOLUME CONTROLS, REPLACE
    AIR VOLUME CONTROLS, GET RID OF
    AIR INLET VALVES
    SNIFTER VALVES
  WATER TANK AIR ADD AT AIR VALVE
  WATER TANK AIR ADD BY DRAINING
  WATER TANK AIR HOW MUCH TO ADD
  WATER TANK AIR HOW OFTEN TO ADD
WATER TANK AIR INLET VALVE
WATER TANK AIR LOSS SIGNS
WATER TANK AIR VALVE REPAIRS
WATER TANK BLADDERS & CAPTIVE AIR
WATER TANK CAPTIVE AIR vs TRADITIONAL WellMate
WATER TANK CONTROLS & SWITCHES
WATER TANK LIFE EXPECTANCY
WATER TANK PRESSURE CALCULATIONS
WATER TANK PRESSURE RELIEF VALVE
WATER TANK REPAIRS
WATER TANK REPLACEMENT
WATER TANK SAFETY
WATER TANK SIZE & VOLUME
WATER TANK TYPES: WATER, OIL, EXPANSION, ALL

• U.S. Gauge Special Application Gauges: Type 300L and 310WJ Air Volume Controls, product description, 2002, Ametek® Inc, U.S. Gauge, 820 Pennsylvania Blvd., Feasterville PA 19053, USA, Tel: 215-355-6900 www.ametekusg.com Customer Service: 863-534-1504, web search 03/23/2011, original source: http://www.jlwinstruments.com/PDF_files/D17_MODEL300-310.PDF
• Rasmussen Well Drilling, Inc., 1793 Hwy 61, Two Harbors MN. Jeremy Rasmussen provides third generation well drilling and plumbing services on the North Shore of Lake Superior. Photos by DJF. Tel 218-834-3387. Email: rasmussenwell@frontier.com
  Quoting: We serve the north Shore – Lake, Cook, St. Louis, Carlton and Pine counties, including Duluth, Grand Marais, Clouqet, Carlton, Finland, Isabella, Silver Bay, Grand Portage, Saginaw, and everywhere in Northeastern Minnesota.

Water Supply & Drain Piping, Wells, Pumps, Water Supply Equipment

• Smart Tank, Installation Instructions, Flexcon Industries, 300 Pond St., Randolph MA 02368, www.flexconind.com, Tel: 800-527-0030 - web search 07/24/2010, original source: http://www.flexconind.com/pdf/st_install.pdf [Copy on file as /water/Smart_Tank_Flexcon.pdf ] -
• Typical Shallow Well One Line Jet Pump Installation, Grove Electric, G&G Electric & Plumbing, 1900 NE 78th St., Suite 101, Vancouver WA 98665 www.grovelectric.com - web search -7/15/2010 original source: http://www.groverelectric.com/howto/38_Typical%20Jet%20Pump%20Installation.pdf, [Copy on file as /water/Jet_Pump_Grove_Elect_Jet_Pumps_1.pdf ] -
• Typical Deep Well Two Line Jet Pump Installation, Grove Electric, G&G Electric & Plumbing, 1900 NE 78th St., Suite 101, Vancouver WA 98665 www.grovelectric.com - web search -7/15/2010 original source: http://www.groverelectric.com/howto/38_Typical%20Jet%20Pump%20Installation.pdf, [Copy on file as /water/Jet_Pump_Grove_Elect.pdf ] -
Cooperative Extension, School of Forest Resources, web search 07/24/2010, original source: http://pubs.cas.psu.edu/FreePubs/pdfs/XH0002.pdf
• Water pressure tanks - how to diagnose the need for air, how to add air, stop water pump short cycling to avoid damage - water storage water pressure tank safety.
• Water pump and pressure tank repair diagnosis & cost an specific case offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost
• Water pressure tank failures & water pump short cycling diagnosis and repair
• Water Supply & Drain Piping, water and drain pipe types, inspection, diagnosis, repairs, problem materials, clogging, etc.
• Water Tests & Fees this water test fee schedule applies when testing is combined with other onsite building inspection services
• Water Testing: background comments on classes of water contaminants, & links to home buyer advice about water testing, drinking water, water supply
• Water Requirements, Home & Outdoor Living

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

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The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop, and from the InspectAPedia bookstore. The 2010 edition of the Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.

• When Technology Fails, Matthew Stein, Chelsea Green Publisher, 2008,493 pages. ISBN-10: 1933392452 ISBN-13: 978-1933392455, "... how to find and sterilize water in the face of utility failure, as well as practical information for dealing with water-quality issues even when the public tap water is still flowing". Mr. Stein's website is www.whentechfails.com/
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