Water pressure tank air pre-charge:

This article describes how to add air to a building water pressure tank and it reviews the function and repair of water tank air volume controls or snifter valves in a building water supply system where a private well is the water source.

Quite often a short-cycling well pump problem can be traced to loss of the air charge in the water pressure tank.

This article describes three alternative methods for fixing that problem. The illustration at page top is courtesy of Carson Dunlop Associates, Inc. in Toronto.

How to Add Air to a Water Pressure Tank

There are fancier methods than those described below but here are three simple methods for fixing a waterlogged water pressure tank, of which the second two work well for easy replacement of air lost from a water storage or pressure tank.

Photo: red arrow points out the air valve found at the tank tee located at the bottomof a water pressure tank. This valve, found at different locations on other tank systems, permits an independent check of system pressure and for tanks that do not use an internal bladder, a valve in this location might be used to manually add air to the tank.

[Click to enlarge any image]

1. Use or repair the water tank air volume control, if one is installed - details about different types of air volume controls (jet pumps) and snifter valves (submersible well pumps) are
   
   at WATER TANK AIR VOLUME CONTROLS
2. Use the water tank air inlet valve or tire valve or "schrader valve" to pump air into the tank - details are
   
   at WATER TANK AIR ADD AT AIR VALVE
3. Drain the water tank using a garden hose and allow air to enter the tank - details are
   
   at WATER TANK AIR ADD BY DRAINING

Other water tank problems such as air leaks, water leaks, or a damaged or burst air bladder, or pressure control switch problems can also make a water system behave improperly. See the links listed

at the ARTICLE INDEX the bottom of this article or start

at WATER TANK REPAIRS for these.

Below we provide a short summary of these methods for adding air to a water tank, and we provide links to in-depth detailed procedures.

1: AIR VOLUME CONTROLS - Method 1: air-volume controls on water tanks

An "automatic" air volume control (AVC) device (on jet pump well systems) or a snifter valve (on submersible pump well systems) may be installed on the water pressure tank if it's an older, bladderless steel tank.

[Click to enlarge any image]

The AVC or snifter valve 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.

This device on older water systems often stops working.

One choice is to get the air volume control working again by cleaning and fixing any leaks - details are

at WATER TANK AIR ADD AT AIR VALVE.

Another choice is to remove the air volume control and plug its fittings if it is leaking, and use one of the other water tank air charge methods described in these articles.

If your water tank air charge is being lost too rapidly, your water tank may have an air leak that can be fixed. Or you may need to replace the tank.

2: Use the water tank air inlet valve or tire valve or "schrader valve" to pump air into the tank

An air valve may be found on the water tank, on piping near the tank or water pump, or at the water tank outlet tee as shown in our photo at left.

Using a bicycle pump one can add air to the water tank.

Step by step details for adding air to a water pressure tank by using the air inlet valve are found

at WATER TANK AIR ADD AT AIR VALVE and

Water tank air valves are also described

at WATER TANK AIR INLET VALVE.

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3: Drain the water tank using a garden hose and allow air to enter the tank

A simple method for recharging the air in a water pressure tank is to turn off the pump, attach a garden hose to the tank drain, open the hose, drain the tank completely, and then let the pump re-fill the tank.

Opening a nearby faucet or valve will speed the drain process and may help let air into the water tank.

Details are

at WATER TANK AIR ADD BY DRAINING

Other water tank problems such as air leaks, water leaks, or a damaged or burst air bladder, or pressure control switch problems can also make a water system behave improperly.

See the links listed at the ARTICLE INDEX the bottom of this article or start

at WATER TANK REPAIRS for these.

More about how we get air into the water pressure tank to avoid well pump short cycling

Air volume controls are found normally only on older type bladderless steel water tanks (photo at left) and not on bladder type captive air water tanks. Therefore the procedures describe here are intended for conventional non-bladder type water pressure tanks such as the water tank shown in our photo (left).

We explain these valves and how they work, are repaired, replaced, or abandoned, in our
article:

AIR VOLUME CONTROLS, WATER TANK

If your well tank is a "captive air" or bladder type pressure tank such as the Well-X-Trol™ series s

ee WATER TANK BLADDER PRESSURE ADJUSTMENT.

Bladderless water pressure tanks and their types, installation, and repair or adjustment are described

at WATER TANKS, STEEL

and

at WATER TANK CAPTIVE AIR vs TRADITIONAL WellMate

Bladder type or captive-air water pressure tanks and their repairs are described

at WATER TANK BLADDERS & CAPTIVE AIR

and at WATER TANKS HOW THEY WORK.

...

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question: how do I add air to the pressure tank?

I need to add water to my water tank. I know you have to drain the tank before adding air, but the manual doesn't say if you add the air with the water valve open or closed. Any help would be appreciated. - Greg Weber 8/3/11

Opps, sorry. I need to add air to my tank, not water. Sorry.

Reply:

John M: replies to Greg W:

I'm no expert but I usually leave my water valve open, this lets the portion of the tank which holds water equalize with surrounding atmospheric pressure. If you close the water valve then pressure will build in that sealed space.

Greg,

If you are adding air to a water pressure tank (by which I infer you are not using the 'total-tank-drain-out' method, and if your tank uses an internal bladder, the water is kept physically separate from the air and it won't matter a bit whether or not your tank drain is open or not.

You are basically pumping air into the air chamber of the tank that is separate from the water (in many but not all bladder type water tanks the water is in the bladder and the air is around it).

If your water pressure tank does not use an internal bladder and you add air to the tank with its drain (or some nearby plumbing fixture open), your incoming air pressure will push more water out of the tank. Now two things can happen, depending on how much air you put in.

If you stop putting in air before all water is pushed out of the tank and the tank pressure is below the pump cut-in pressure your water pump will come on and repressurize the system normally.

If you keep putting air into a bladderless tank and the water pump is left turned off, eventually you'll push all of the water out of the tank and air will start coming out of your tank drain or nearby faucets. That won't hurt anything, provided you don't lose pump prime.

You'll have charged the tank by emptying it of water completely, the equivalent of our 'total-tank-drain-out' procedure. When you close the tank drain or faucet and turn your pump back on the pump will return water to the tank and pressurize the air in the tank at the same time. If your water tank has excess air that will pass out through plumbing fixtures until the system stabilizes. - DF

Complete procedures for adding air to the water tank are

at WATER TANK AIR, HOW TO ADD

Water Pump Turns on Immediately When we Run Water

Question: Goulds jet pump 3/4 hp, pump always comes on right away when water runs

i have a JRS7 Goulds jet pump 3/4 hp, recently i have been encountering a problem which i cant seem to rectify. my pump is set that immediately when any tap is opened it will come on and cut off when closed.

it will run for the period while the water is being used but, the pressure however drops sometimes while in use to 0 psi on the guage resulting in the pump cutting off immediately and no water is being delivered.

i have changed the pressure switch and am still experiencing the problem. the thing no matter what i try while it is off it will not come back on until it feels like it then the guage will build back up to 45 psi and it will run for a while and then do the same again. please help - Shawn White 7/23/11

Reply:

Shawn, if a pump always comes on immediately when you open a faucet and shuts off when you close the faucet, your water pressure tank is water logged - it's lost its air charge.

See the article titled WATER TANK AIR, HOW TO ADD (links at the ARTICLE INDEX the bottom of this article )

You might also have a problem of sediment clogging at the pressure sensing switch and gauge both - even if you replaced the switch if its mounting tube were clogged the problem would continue.

Question: pump turns on as soon as spigot opened

(June 13, 2014) Anonymous said:

My pump comes on as soon as the water is opened and continues going on and off until the water is closed. What is the problem and how can I correct it

Reply:

Anon,

Before changing the pressure control switch setting I'd look at either having run the well out of water (pump can't send up enough water to reach the cut off pressure)

or the pump impeller is damaged (pump can't develop enough pressure to reach shutoff)

other explanations include well piping leaks or a damaged pressure control switch

Question: water pressure goes down to next to nothing

(May 2, 2015) carl mcevers said:
water pressure goes down to next to nothing after a few seconds of turning it on

Reply:

Sounds as if there is a waterlogged pressure tank and a slow-flow or low capacity pump. Clogged or very small diameter piping combined with low water pressure can have this effect as well.

Question: water pressure falls immediately from 60 down to 40 and pump cycles on and off

(June 24, 2014) Anonymous said:

My pressure is set at 60 to 40, When you turn the water on it drops from 60 to 40 immediately and will continue to turn on and off until the water valve is turned off. The pump basiclly want shut off until you stop using water

Anon when pressure drops immediately on opening a tap I expect that there is little or no air charge in the pressure tank.

Take a look at

WATER TANK AIR, HOW TO ADD

 

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Continue reading at AIR INLET VALVES or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see WATER TANK AIR, HOW TO ADD FAQs - questions and answers posted originally on this page

r see these

Articles on Adding Air to the Water Pressure Tank

• AIR VOLUME CONTROLS, WATER TANK
• SNIFTER & DRAIN BACK VALVES - may explain water tank air loss
• WATER PUMP & TANK I&O & REPAIR MANUALS - installation, operation & repair guides for all brands
• WATER TANK AIR, HOW TO ADD
• AIR DISCHARGE at FAUCETS, FIXTURES
• SNIFTER & DRAIN BACK VALVES
• WATER TANK AIR VOLUME CONTROLS
• 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 BLADDERS & CAPTIVE AIR

Suggested citation for this web page

WATER TANK AIR, HOW TO ADD at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to WATER SUPPLY, PUMPS TANKS WELLS

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Citations & References

In addition to any citations in the article above, a full list is available on request.

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