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This article describes how to identify, diagnose and repair of WellMate™ 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. Readers of this document should also see WATER TANK BLADDER PRESSURE ADJUSTMENT where we discuss adjusting air pressure in a bladder type water tank to factory specs, and 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. The illustration at page top is courtesy of Carson Dunlop.

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

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:

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

Type 1 or captive air water pressure tanks sold by WellMate and 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 conventional steel water tanks 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 inflater 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.

• For a water system that turns the pump on at 30 psi and off at 50 psi the bladder pressure should be set to 26 psi.
• For a water system that turns the pump on at 40 psi and off at 60 psi the bladder pressure should be set to 36 psi.
• Do NOT over pressurize the water tank - it could burst and injure or kill someone.

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. See the installation manual at http://www.wellmate.com/pdf/UT_HP_SPTank_Install.pdf

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.

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If Your Water Tank is Not Working Properly See These Diagnostic Guides

WATER TANK AIR, HOW TO ADD
  WATER TANK AIR LOSS SIGNS
  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 BLADDERS & CAPTIVE AIR
WATER TANK CAPTIVE AIR vs TRADITIONAL WellMate

If You Need Help Diagnosing a Loss in Water Pressure or Other Pump & Well Problems See These Guides

WATER PRESSURE LOSS DIAGNOSIS GUIDE
WATER PRESSURE & FLOW MEASUREMENT
  Water Pressure Intermittent
  No Water Pressure
  Water Pressure Falls Slowly, Erratic Pumping
  Water Pressure Tank Problems
  Water Pressure Tank Diagnosis
  Water pipe clog diagnosis
  Water pipe clog repair guide
  Making the "right" repair
  PUMP, WATER PRESSURE BOOSTER
  Typical Water Tank & Pump Prices

PLUMBING TOPICS
APPLIANCE EFFICIENCY RATINGS
OIL TANKS
SEPTIC SYSTEMS
WATER PRESSURE REGULATOR ADJUST
WATER PRESSURE REPAIR GUIDE & COSTS
WATER PRESSURE LOSS DIAGNOSIS GUIDE
WATER PRESSURE & FLOW MEASUREMENT
  WATER PUMP PRESSURE CONTROL ADJUSTMENT
  WATER PUMP PRESSURE CONTROL REPAIR
  WATER PRESSURE REGULATOR ADJUST
WATER PUMPS & WELL TANKS
WATER PUMP CONTROLS & SWITCHES
WATER PUMP SHORT CYCLING
WATER PUMP TYPES & LIFE EXPECTANCY
WATER PUMP & TANK SAFETY
WATER SHUTOFF VALVE LOCATION, USE
WATER SOURCE ALTERNATIVES
WATER SUPPLY & DRAIN PIPING
WATER TANK TYPES: WATER, OIL, EXPANSION, ALL
  CAPTIVE AIR BLADDER WATER TANKS
  STEEL WATER TANKS
  BIG WATER STORAGE TANKS
  OPEN WATER TANKS
WATER TANK LIFE EXPECTANCY
WATER TANK REPAIRS
WATER TANK AIR, HOW TO ADD
WATER TANK BLADDERS & CAPTIVE AIR
WATER TANK BLADDER PRESSURE ADJUSTMENT
WATER TANK PRESSURE CALCULATIONS
WATER TANK PRESSURE GAUGE
WATER TANK SIZE & VOLUME
WATER TANKS HOW THEY WORK
WATER TESTING
WELLS CISTERNS & SPRINGS

• WellMate Water Tank Types and contact information are provided here. At their website the company provides product descriptions as well as installation and repair guides for water tanks and other products. For the two water tank types discussed in this article see:
  wellmate.com/products_ca.htm - captive air water tanks (replaceable air cell or bladder)
  wellmate.com/products_trad.htm - traditional residential water tanks with a tank top mounted air volume control - also called hydro-pneumatic water tank
  Wellmate Pentair Water Corp., 220 Park Drive, Chardon OH 44024 can also be reached at 440-286-4116.
• Amtrol Extrol™ pressure control tanks used on hydronic heating and other systems such as models 35LBC, 50 LBC, 85 LBC, and 100LBC to 600 LBC also use a bottom bladder containing air - see amtrol.com/pdf/LBCSeriesEXTROL9017-095.pdf for details.
• Thanks to reader Nancy Martin for suggesting this topic - July 2009

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