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WellMate hydropneumatic water storage and pressure tank (C) Daniel FriedmanWellMate™ Water Storage & Pressure Tanks - Diagnosis & Repair
Fiberglass or Composite bladderless & bladder-type well tanks

Fiberglass, composite or plastic water pressure tanks:

This article describes how to identify, diagnose and repair of WellMate™and similar water tanks, including both internal air bladder-type tanks (WellMate™ captive air water tanks) and bladderless traditional or hydro pneumatic type water pressure tanks such as the WellMate™ Traditional Air/Water tank: how they work, what goes wrong, how to fix it.

We also describe WellMate's Micronizer, an air volume control device used with the company's well tanks to keep the proper air charge in bladderless water tanks.

We review: how to identify the type of WellMate™ and similar types of fiberglass water tanks. How to diagnose & repair a burst air bladder in a WellMate™ water pressure tank. How to diagnose & repair lost air pressure in a non-bladder traditional WellMate hydro-pneumatic water tank.

How to diagnose and repair water system problems when an internal bladder water tank is installed and the bladder is used to contain air, not water. Broken, burst, busted or leaky water tank.

Captive air tanks that incorporate an internal, replaceable air cell or bladder, and bladderless hydro pneumatic water tanks (shown at the top of This article ), also called traditional residential water tanks that incorporate no internal bladder but use a tank top mounted air volume control.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

- Daniel Friedman, Publisher/Editor/Author - See WHO ARE WE?

How to Diagnose & Repair WellMate™ type Bladder or Non-bladder Traditional Water Tanks

Wellmate Pentair SidePort SP Water tank at InspectApedia.comIllustration: a Pentair - Wellmate fiberglass, side-port or SP-series non-bladder water pressure tank. The company's WM-series pressure tanks use an intenral air cell (or bladder). WellMate SidePort or SP-series water tanks do not use an internal bladder.

Here we provide WellMate & Pentair & other brand contact information, water tank / well tank installation and operation manuals, and troubleshooting advice.

[Click to enlarge any image]

Reader Nancy Martin asked how to diagnose well pump short cycling and a possible water tank or bladder problem for the WellMate bladder-type water tank which uses the tank bladder to retain the air charge in a water pressure tank.

WellMate™ describes two types of water pressure tanks used in residential and light commercial applications:

Our WellMate links near the bottom of This article can direct you to photographs that help identify which type of water tank is installed at your property.

Which Type of WellMate or Fiberglass Water Tank is Installed?

These are different tank designs so first we need to know which type you have - take a look at the photos at the two WellMate links.

Captive Air Water Pressure Tanks with an Internal Air Bladder

Pentair Wellmate fiberglass water pressure tank cite & discussed at InspectApedia.com ... Pentair Wellmate fiberglass water pressure tank cite & discussed at InspectApedia.com

Type 1 or captive air water pressure tanks sold by WellMate and the company's WM well tanks, and similar tanks from some other manufacturers are constructed of fiberglass and use an internal bladder to hold the air charge.

If the air bladder has ruptured, the water tank will begin to act like an old-fashioned steel water tank - air absorbs into the water until there is not much air charge, the tank becomes water logged, and the well pump will short cycle on and off.

Our description of WATER PRESSURE TANKS, STEEL - separate article adds details.

If the air bladder has failed, the tank will act much like a type 2 hydro pneumatic or traditional water tank.

Tips for Testing & Repairing a Captive Air Water Tank Bladder

Try this: if you have this type of tank, remove the valve step cap covering the bladder inflator valve located on the top of the tank. Using a small implement, MOMENTARILY (just for a second) depress the valve pin in the center of the valve stem down to see if air or water comes out. If water comes out of this valve the air bladder has burst.

But the bladder could be burst but blocking the valve in which case nothing will happen. If air comes out of this valve the the tank bladder contains air and may not have burst.

If air comes out of the valve, use an accurate tire gauge to check the air pressure at the valve.

If the air pressure is 4 psi below the well pump cut-in pressure then the air bladder is probably fine. If the air pressure is less than that figure, using a bicycle pump, just add a little air to the bladder until it is set to the proper number - 4 psi below the pump cut-in pressure.

Draining the water tank itself and adding air to a bladder type tank itself through the (ruptured) bladder valve at the tank top of a tank with a failed bladder MIGHT work to improve performance for a while (until the air is reabsorbed back into the water over time) but you need to replace the bladder.

A guide to replacing the air bladder in the WellMate captive air tank is provided by the company at http://www.wellmate.com/pdf/Residential_AirCell_Replace_Instructions.pdf

The air bladder in the WellMate™ type water tank is to be inflated to 4 psi below the well pump's "cut-in" pressure.

The installation manual for this tank is at http://www.wellmate.com/pdf/Residential_CaptiveAir_Tank_Install_Manual.pdf
The tank has a 5 year warranty so check your records of when the tank was purchased to see if that applies.

Tips for Testing & Repairing a Traditional Hydro-Pneumatic (no internal bladder) Fiberglass Water Tank

Type 2 tanks, described by WellMate as hydro pneumatic water tanks, do not incorporate an internal bladder but rather an air volume control valve that replaces air into the tank as needed. These tanks will perform better than older steel water pressure tanks because we don't face the concern of rust perforation of the tank.

If the air volume control (AVC) fails, the tank will act much like a type 2 tank

See TANK TYPES: WATER, OIL, EXPANSION, ALL and scroll down to the description of older steel water tanks. In this case you may need to replace the AVC.

Draining and adding air to an AVC type tank with a failed AVC also MIGHT work to improve performance for a while (until the air is reabsorbed back into the water over time) but you need to replace the AVC.

Water tank bladder air pressure adjustment: also review

WATER TANK BLADDER PRESSURE ADJUSTMENT if you are adjusting, tuning, or replacing the air pressure in your bladder-type well tank.

Reader Question: how can I tell if my water pressure tank uses an internal bladder?

How can l tell which pressure tank l have - with Bladder or without. I have CBAKX on the tank. 42 gallon upright A drain plug at the bottom an inpipe an out pipe and a pipe for pressure gauge. - Oliver 9/10/12

Reply:

Oliver, see WATER TANK CAPTIVE AIR vs TRADITIONAL WellMate for a comparison of these two types of water pressure tanks.

WellMate / Pentair Contact Info & Manuals

We found it nearly impossible to find water tank instalallation manuals at Pentair's website (December 2021) but we provide what we've found elsewhere, below. You can of course contact the company directly to ask for help as we provide Pentair/Wellmate contact information first.

see also

  • AO Smith DIAPHRAGM WELL TANK INSTALLATION MANUAL [PDF] (2009) A. O. Smith Corporate Headquarters, 11270 West Park Place, Suite 170, P. O. Box 245008 Milwaukee, WI 53224 USA, email: help@hotwater.com, Tel: (800) 527-1953, the company has offices world-wide , website: https://www.aosmith.com/contact/ - retrieved 2021/12/02 original source: https://aosmithme.com/wp-content/uploads/2019/02/Instruction_Manual_PMI.pdf
    Also see
    (800) 527-1953

...


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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-12-02 by Inspectapedia Com Moderator (mod) - Install or Adjust the WellMate Micronizer air volume control device

WellMate Micronizer air volume control for WellMate water pressure tanks cited & discussed at InspectApedia.com@Ted

For other readers, the WellMate Micronizer, shown here, is a device intended to keep the proper air charge in a water pressure tank that does not use an internal bladder. That air charge is necessary to prevent well pump short cycling as water is being run. This device is an alternative to the much older traditional AVC or Air Volume Control device (that in our OPINION proved not so reliable). The Micronizer works on water systems with a water flow in the range of 5 - 15 gpm.

The company describes the Micronizer, as we quote:

The Micronizer is designed to be installed in the water line just prior to the inlet of the hydro-pneumatic tank it serves. This mechanism is a venturi that draws air into the water line through the air inlet.check valve combination to continually charge the tank with air. The excess air in the tank is relieved through an AVC assembly installed in tank.

The Micronizer is shipped with the indicator arrow set at 15 degrees on the dial. This closes slightly, the larger of the two open holes inside to create a pressure differential that allows air to be drawn into the water line. The amount of air drawn in and draw time is adjusted with the adjustment knob.

Details are in

WellMate MICRONIZER INSTALLATION [PDF]

and in

WellMate MICRONIZER INSTRUCTIONS [PDF]

Ted: if you don't have that second document take a look at the PDF we provide from WellMate, as it has critical instructions on how the device must be adjusted based on pump run-time.

Don't assume the Micronizer is "shot" - it may simply need proper adjustment, as we show in this excerpt from the Micronizer instructions PDF cited above.

Let me know if reviewing the Micronizer adjustment solves the trouble.

On 2021-12-02 by Ted - close-up of WellMate tank installation

WellMate water tank showing Micronizer installation details (C) InspectApedia.com Ted

On 2021-12-02 by Inspectapedia Com Moderator (mod)

@Ted,

Thanks for a stump-the-chump question (borrowed from click and clack the tappet brothers on Car Talk)

Indeed we need to get air into the pressure tank to stop the pump from short cycling.

But I'm unclear on what happened to your Micronizer. Can you tell me the brand and model so that we can check it's installation and operation manual? Is it the WellMate device ? (probably)

On 2021-12-01 by Ted - Short-cycling pump with Well Mate HP-9 bladderless tank & micronizer

Have Well Mate HP-9 bladderless tank with micronizer to mix air with incoming water to oxidize iron, then send water thru green sand filter which vents into dug well, along with 1/4" snifter hose from top of HP-9 tank.

Pump was cycling on/off continuously, tank was water logged, so afraid pump would quit, I drained tank, removed snifter and plugged it's port to get over night water.

When refilling tank, I noticed micronizer was sucking air non-stop, while, I think it used to suck air in pulses when system worked correctly.

Micronizer sucked continuously until tank reached about 30PSI. Pressure switch turns on at 30, off at 50. From 30 to 50 PSI micronizer did not suck air.

My question is: is micronizer shot, or confused becaused snifter/float no longer operating, or is there problem with float/snifter, or both?

WellMate water tank showing Micronizer installation details (C) InspectApedia.com Ted

On 2020-11-01 by (mod)

A photo or model number of your water tanks would be helpful here. A typical water pressure tank is designed to work with an air charge. It's possible that one of your tanks uses an internal bladder and the other does not.

Or perhaps you have some type of water treatment equipment. I really can't guess further without knowing more or seeing some photos

On 2020-10-31 by Sher

I have two wellmate tanks hooked up side by side ,one is the pressure tank where you can add air and the other has no air valve.

What is the tank called with no air valve? We cant seem to keep water coming into the house and it is not the pump in our well. Could it be this other tank? We cant seem to find this other tank anywhere. Please help

On 2020-07-31 by Joe

Thanks for the great information.

I have a Wellmate fiberglass tank with a captive air bladder that seems to be leaking.

Unfortunately the replacement bladder part for this tank has been discontinued.

Is it possible to remove the bladder and patch it? Like with a rubber cement bicycle tire patch kit?

On 2018-11-18 by (mod) - repair of pinhole leaks in WellMate water pressure tank

Understood, but a paste on or over isn't do reliable.

On 2018-11-15 y Jeff

Thanks. But it's so small I hate to put a sheet metal screw in and open up the hole even more. Was thinking more like a patch of some sort

On 2018-11-15 by (mod) -

Jeff

I would try using the combination repair of a short sheet metal thread type repair screw with suitable washer that actually will stop the leak.

Once that's in place so that I have a dry surface I might coat that with an epoxy

That sort of repair only works on a tank that is not at risk of being perforated by rust from the inside. As your tank is fiberglass it sounds like that is likely to be the case

On 2018-11-15 by Jeff

Can I fix a pinhole leak in a well mate fiberglass tank? I believe this is what's called a contact tank not a pressure tank

On 2018-09-30 by (mod) -

Doug

I agree; it's typical to see a slight pressure drop right after the pump shuts off.

But dropping from 54 to 38 psi - if the measurements are accurate - sounds as if there's a leak somewhere.

It might be that you don't have enough of an air charge in the tank - I want to see the water level no higher than 2/3 of the tank height or volume when the pump shuts off; often you can determine that by the condensate line on the tank exterior.

This article series also shows how to add air to the pressure tank. There are several approaches. One is

at WATER TANK AIR ADD AT AIR VALVE

That can give you a longer drawdown cycle. But that won't explain the pressure drop.

On 2018-09-30 by Doug

I believe that it is normal for the water pressure to drop 2 or 3 lbs. after the pump stops pumping but on the 120 gallon tank it cuts out at 54 lbs. then drops to about 38 psi. I do manage to get a couple gallons of water before it cuts in at 32 lbs then pumps up to 54 lbs and then drops to 38 lbs before any water is used.

Will adding more air to the tank help this or will it eventually increase over time? Thanks again for your time.

On 2018-09-30 by (mod) - water pressure dropped from 54 psi to about 38 psi

Doug:

The pressure you see in the system is not a feature of the tank; rather the pressure is created by the pump. So if the pumped water pressure only reaches 38 psi that must be where the pressure control switch turned off the pump.

The fact that you see only 1/2 gallon of water before the pump turns on could mean that the tank is waterlogged - not successfully drained or air-charged, OR that the control switch is not set properly or not working properly. A debris clogged pressure switch can, for example, give odd behaivour and may not turn on and off when it should in response to water pressure.

On 2018-09-30 by Doug

I emptied the tank and closed the valve at the top of the tank. When filled it was pressurized the trouble is that the water pressure dropped from 54 psi to about 38 psi.. Is this common for a bladder-less tank system? There is also a smaller pressure tank with a bladder in it within the system.

When I use this tank alone the pressure drops from 54 psi to about 51 psi but I only get about a half a gallon of water before the pump kicks in. Thanks for your help.

On 2018-09-24 by (mod) - How do I convert a 120 gallon storage tank into a pressure tan

Empty the tank, and then with the tank at atmospheric pressure when you refill it will have an air charge. You probably need to add an air volume control or you need to periodically add air to the tank

On 2018-09-23 by Doug

How do I convert a 120 gallon storage tank into a pressure tank. I don't believe it has a bladder in it. There is an air injection system now does this work like a pressure tank. Thanks for your help.
Doug

On 2017-10-24 by (mod) - normal water pressure tank pressure reading

John the pressure in your water pressure tank will be somewhere between the CUT-IN pressure and CUT-OUT pressure set on the pressure control switch.

Two common range settings are 20/40 psi or 30/50 psi.

On 2017-10-24 by john

80 gallon bladder tank.What should the pressure read when you place gauge on air vent on top of tank?

On 2017-03-19 by (mod) - contact for WellMate

Yes, your wellmate pressure tank uses a replaceable air cell. Contact Wellate at

http://www.wellmate.com

On 2017-03-19 by Murugaiyan

In my pressure vessel Model WM0450 bladder got damage. Is it possible to replace new one.

On 2017-03-19 by (mod) - replacable air cell or "bladder" in a WellMate pressure tank

Yes, your wellmate pressure tank uses a replaceable air cell. Contact Wellmate at the address or website given at the end

of WATER TANK CAPTIVE AIR vs TRADITIONAL WellMate

On 2017-03-19 by Murugaiyan

In my pressure vessel Model WM0450 bladder got damage. Is it possible to replace new one.

On 2016-04-22 by (mod)

Ellie if you are having repeated pressure tank failures something is wrong. But if the problem is simply loss of the air charge, it sounds to me as if an automatic air volume control is missing or not properly installed.

On 2016-04-22 by Ellie

What can you do if the pressure tanks keep going out-needing to be replaced because they are full of water-about every 5-6 months? Nobody can figure out why. They are still under warranty and are installed by a knowledgeable well person.

On 2015-07-17 by (mod)

TB

It is normal for a pressure tank to fill only part-way, as the air charge in the top of the tank occupies the remaining space.

On 2015-07-17 by TB

Our wellmate UT-120 tank is only partially filling up. How can we correct this?

On 2015-05-26 by Ginny

Water comes out of the valve on top of the pressure tank, what does that mean?

Question:

(May 4, 2014) Harry said:
I have a fiberglass bladderless water pressure tank through which I pump water through a filter system then to a rooftop storage tank which then supply the building by gravity flow.

The bladderless tank has a valve on its side to allow air to enter the tank. How do I know when the tank has too much water and so needs draining to let air in?

Reply:

Harry, if the water tank does not have enough air (that is it's waterlogged) you'll notice it because the pump will cycle on and off rapidly.

See WATER PUMP SHORT CYCLING for details.

Question:

(Sept 22, 2014) Anonymous said:
hello
can you tell me if a wellmate pressure vessel wm330 is suitable for outside weather conditions, i.e. -10c to 30c. thanks
tim

Reply:

Anon any water pressure tank needs to be protected from freezing. You can locate the tank in a well pit below the frost line or construct a heated enclosure.

See WELL PITS

Question:

(Sept 28, 2014) deanpeddle said:
I have a wellxtrol tank by amtrol and a submersible pump in my shallow well. my pump will run (and push water) if i manually hold the bypass lever at the 'auto' position but always shut off when released. the tank has NO WATER in it at all.

I replaced the pressure switch and cleaned out (it was blocked) the small inlet line the pressure switch is mounted on. could a blockage in the line going to the tank cause the problem i'm having with the pump not cutting in at all?

Reply:

Yes you are correct. But check first for a debris-blocked pressure sensing port on the pressure switch.


...

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